 Good morning. Good afternoon, dear participants. A very warm welcome to all of you to the IHE Delft Alumni and Partners online seminar, a collaboration between IHE Delft and the Water Channel. My name is Longhua and I am program manager from the Water Channel. It is my great pleasure to facilitate today's seminar on the topic of sanitation and groundwater, revealing the hidden links and risk management. This seminar is part of our online seminar series under the Alumni and Partners program at IHE Delft. And of course, as 2022 is closing, we are very pleased to join you all here when the festive season is about to start. This year in 2022, we celebrated the World Toilet Day. And this year, we also dedicated the World Water Day to groundwater with a theme making the invisible visible. Both events underlined the impact of sanitation on groundwater. And we feel the importance of insights and perspectives about the highly relevant, yet often invisible linkages between sanitation and groundwater quality. In this context, we dedicate this seminar to discuss mechanisms of groundwater contamination from sanitation sources and the associated risks on water supply and public health. Furthermore, we will hear about two case studies on urban aquifers affected by wastewater infiltration. In this panel discussion follow up in the Q&A session, we will invite all of you to share questions and remarks and thoughts on the topic. And we will also explore management strategies and solutions. And we will do all of this with our two special speakers of today. It is my pleasure to introduce Dr. Konstantina Velkushanova. Dr. Velkushanova is senior lecturer in non-suit sanitation at IHE Delft. She has a vast experience of 20 years working in wash and sanitary engineering. She spent nearly a decade in University of KwaZulu Natal in South Africa, where she has been working on different research projects and activities on non-suit sanitation, fecal sludge management, development and evaluation of innovative sanitation technologies and capacity building. She is actively involved in different programs and initiatives supporting the global sanitation agenda. And very recently, she also the lead editor of the recently published book, Methods for fecal sludge analysis, aiming at a standardized approach for fecal sludge analysis worldwide. She is also a coordinator and lecturer of the educational programs under the largest capacity building network in CIRIS, the Global Sanitation Graduate School. Thank you very much Konstantina for joining us today. Our second speaker of today is Dr. Jan Wilhelm Fopen. Dr. Fopen is associate professor of hydrology at IHE Delft. He has a master degree in hydrology and a PhD from the Free University, VU Amsterdam. In 1995 and 1996, he was stationed in Sanaa, Yemen, where he was part of a project team aimed to identify sources for drinking water supply of Sanaa. Intrigued by poor groundwater health conditions in Sanaa, he focused on transportation of the fecal indicator organism. And as CIRCOLI, I'm sorry if I make it wrong with the pronunciation, maybe Jan Wilhelm can help me later. Insaturated progress media whereby the aim was to extend the colloid filtration theory. This work has resulted in about 10 publications in peer review journal. Dr. Fopen works intensively on groundwater management and modeling across different contexts. Thank you very much Jan Wilhelm for taking time for joining us today. Before we begin with the presentation, I would like to take a brief moment to mention some of the logistic points. We welcome you all to have an interaction with our speakers by posting questions in the chat box. And please feel free to introduce yourself. I've seen that a lot of our participants are already doing so, so great. Thank you very much. We will collect all these and address them in the Q&A session. All information and recording of our webinars will be available at the Water Channel website as well as the IHE dedicated website. We will share all follow-up information with you after the event. And lastly, we'd like to thank Ms. Maria Laura Sorrentino, the Alumni Relations Advisor for my IHE to be with us today. Thank you for mobilizing IHE with faculty, students, and it's very active on my network in organizing this seminar series. And without any further due, I would like to invite our first guest, Dr. Velku Sanova for her presentation. And over to you, dear Konstantina. Wonderful. Thank you so much for the wonderful presentation. I just wanted to mention this in the beginning. So my focus is mainly on sanitation, and I'm not a groundwater expert, but my dear colleague, Young Willem, is the expert on the groundwater. So I think for just a disclaimer that we have this distribution between us. But I think it's a wonderful combination to share some of the aspects on why sanitation is so important to pay attention to. And the groundwater contamination pathways are one of the important aspects that we often cannot see. That's why we had this theme of the World Water Toilet Day. It's an invisible problem, but it's quite a serious problem. So where are we today? Well, if we have a look, we see that we have quite a significant progress maybe achieved towards the SDGs. But at the same time, we see that we have quite a few more aspects to consider, and we need to do quite a lot more work. So if we want to get where we want to get, especially for achieving SDG6, we need to go four times, five times, nine or even 15 times faster in some of the low and middle income countries where some of the development is not so progress. So what is the current situation in the world in terms of distribution of sanitation facilities? Well, this is a very beautiful data from the Joint Monitoring Program. And we can see that usually in the world we have quite a significant disparity in the distribution of sanitation services. So for example, we can see is that in high income countries, the most of the sanitation is safely managed. And then we have some form of a basic sanitation. But if we have a look at countries in Central or Southern Asia, the safely managed sanitation ratio reduces quite significantly. But if we see even in sub-Saharan Africa, this number is reducing more and more. And what is important to see is that in some of these regions, we have quite a lot of distribution of unimproved sanitation or open defecation, which is one of the direct impacts also on the groundwater services. So here we can see what is a safely managed sanitation. This is improved facilities which are not shared with other households and where excreta are safely disposed in situ or transported and treated offsite. So we can see that quite a lot of the safely managed sanitation facilities are mostly focused in the north. And in the contrary, if we want to see the share of the population without access to improved sanitation, we can see that the most significant impact is lying in Africa and then in some parts of Asia. Improved sanitation facilities are designed to hygienically separate excreta from human contact. They could be flush and pipe water, sewer system, septic tanks, pit latrines, improved pit latrines, composting toilets, etc. So what we see here in the red is that actually in these parts, we have in some places over 60% of the population don't have access to safely managed sanitation. So how do we make the link with the drinking water facilities? Well, let's have a look at the distribution again in safely managed drinking water supply, basic, limited or unimproved. We can see again that in some parts, and once again in sub-Saharan Africa, for example, we have only 30% of the water provision is safely managed. We have basic, about 35%, and we have quite a large number yet of access which is limited or unimproved, with nearly 7% not having access or having access only to service water in the sub-Saharan region. And once again, if we try to translate this, we see that again in almost the same regions where we have unimproved sanitation, we have problems related to water management. So in this figure, we see what is the share of debts attributed to unsafe water resources. And in Africa and sub-Saharan Africa, this could be up to 8% or 10% of the overall debt ratio, which is also quite prominent in India. So what does it mean? Well, there is a significant global health impact due to the inadequate sanitation. There's some stats from the World Health Organization, how many people die due to the real diseases. So unsafe sanitation is the major factor contributing to the transmissions and outbreaks of some diseases like corridor or typhoid or hepatitis. There is also a significant problem in some places with the distribution of helmets, which are causing parasitic infections. And we don't only speak about health issues, but we speak about societal issues. So when we speak about basic form of sanitation, it's usually stigmatized and associated with poverty, which also causes social inequalities. And because of the poor sanitation and the water supply, currently the world pays about 260 billion US dollars per year, which is going towards health care, loss of opportunities and many, many, many other things. So we have what I've tried to do is try to create the link between sanitation and safe water provision globally. So we saw that there is a disparity in the sanitation provision. We currently have about 40% of the world population lacking access to adequate sanitation, about 3.6 billion. And then they use existing onsite sanitation systems that are often not so safe to use. They don't have safe treatment or they go discharged directly into the water bodies. At the same time, we have some systems in between, which are septic tanks or improved pit latrines that provide some form of a safe capture, but they are related to a lot of challenges in maintenance. And once they are not maintained properly, they also pose risk to the environment. And we have, of course, the traditional waterborne sanitation systems, which are the sewer, waste water treatment plant, but unfortunately this is not possible in many of the countries that we saw some examples. I would mention why, but one of the reasons is that they could be very costly. So these are some examples to see how is sanitation managed in some parts of the world. So this picture, for example, is from Durban in South Africa where it used to work. This is a ventilated improved pit latrine that has been soaked with a lot of liquid, which clearly had been infiltrating during the rainy season through the groundwater. And of course, there is a lot of trash inside, which makes it very difficult to manage. These are some other examples from other parts on the left bottom is from Cape Town. We have some of them from Kenya and this picture as well. So this is just to give the contrast in some regions, how we are dealing with sanitation. In other parts of the world, we have really greatly managed wastewater treatment plants. But what happens is that, unfortunately, this cannot be achieved as a safely managed option through the entire world. Why? Well, firstly, I mentioned that it could be quite costly. It requires huge investments and also it requires huge investments for operation and maintenance. Another factor is the water scarcity. So we have in this map is showing a prediction on the water stress by countries. And what we see is that quite a lot of the countries worldwide would be at high or extremely high pressure, which shows the ratio of withdrawals to available water for supply. So clearly, this is not an option for trying to sewer every part of the world. On the top of this, we have a significantly increased in the world population and the urbanization, which contributes to a lot of other challenges. So what we saw in the World Toilet Day this year, we celebrated the connection between... Well, we celebrated the World Toilet Day and we wanted to raise awareness about the problems that could be caused by on-site sanitation, that could not be safely managed and the access to groundwater supply, which contradictory in many places, they could be very, very close. And we can see some examples. Okay, so this is a summary. This comes from the Companion of Sanitation Systems and Technologies by EVAC, which is based in the Switzerland. So we see here a distribution between different options for on-site sanitation systems. So the purpose of all of them is, of course, to provide safe containment where the excreta or the generated black water, wastewater, is contained safely so then it doesn't pose health or any environmental pollution risks before it's been emptied and transported and treated safely. So we have single pit latrines, we have double pit latrines, we have different options, septic tanks. It depends what kind of toilet it is, whether it's a flush system, whether it's a dry system. So there is a variety of options. But what we see in reality is once we have these installations, in many parts they may not work properly or they may pose partially a risk to the environment and pollution of the surrounding soil and surrounding groundwater. So this example is showing how the bottom of the pit latrines could be open. So if it's not lined properly then we can have leaking into infiltration through the soil. In rainy seasons pit latrines could be also flooded from the rain flow and this again ends into the groundwater. This example is showing us septic tanks which could also pose a risk to the environment if it's not maintained and managed safely. For example, if we have different cracks in the piping, if we have not regular emptying, so the effluent is overflowing to the environment. In the local area we can also have cracks or something not functioning properly in the outlet drain into the surrounding water bodies. There are of course design considerations of minimum distances between the sanitation systems, minimum depth, depending again on the availability of how shallow is the groundwater. So there are quite a few regulations, but in reality in many places not all the regulations for building these systems are strictly followed yet. In many households built digging the pit latrines without any lining just because this is the only option they can afford. And what are the dangers? Well we speak about pollution but the main aspect is related to public health. So fecal sludge or feces contain a lot of different pathogens. And once they end up into the environment and into the water bodies, this is becoming a problem because this causes the spread of waterborne diseases. And we can see how this zooming a little bit more, how this can affect the situation in the general water services, the water supply and the quality of the water that we are going to use for water supply. In many locations in the world the piped water supply may not be possible, for example in rural settings where the most of the households would use wells or boreholes. And if we have the pit latrines that are deep or for some reason the leachate is partially ending into the groundwater table, then this results into the users taking contaminated groundwater. Not only this but the groundwater eventually joins with the surface water sources which also just distributes the contamination. So this is the brief case study from Uganda by one of my students Julius who graduated this year. So he was looking at linkages between sanitation and groundwater. He had a very short time and Young Dilem has a much more extensive knowledge to share also from Uganda and linkages. But what I wanted to show you here is he was looking at different aspects related to distance of the water supply resources to the on-site sanitation. So one of the background that he has been dealing with is that the low piped water service coverage in the urban areas has led to reliance on groundwater sources as an alternative. There is a major reliance on on-site sanitation, but at the same time because of the faster population growth, this poses additional risks because the on-site sanitation systems are becoming closer and closer to the different groundwater sources like boreholes or wells. So these are some pictures you would see a few more from Young Dilem and Julius did some studies with questionnaires from the households. So he was just interested to see what type of sources the most of them use. And it turns out that 20% of them rely on borehole, only 2% rely on tap water and 70% take water from two sources, two or more sources. There are shallow wells and protected springs. He has been looking at some potential outbreaks or common illnesses between the same interviewees and about 25% reported that they commonly have diarrhea. 9% reported typhoid and some other diseases. And of course malaria is not related to this part. And quite a lot of them are aware of the problem and somehow the answers here show that there is an awareness that the water is not very clean because 96% reported that they use boiling of the water before consumption. So what Julius found out here is that there is a link between the distance of the on-site sanitation systems to the concentration of E. coli and total coliform respectively. So I'm not going to go anymore into this study and I wanted to end with a few slides on how do we bridge the gap. So I gave you an overview of what are the impacts, what is the sanitation challenge and how it's virtually impossible in some places to install sewer type of systems. But we also cannot accept to have unsafe sanitation and SDG.62 is looking at the provision of safe sanitation for all. So one of the aspects is that there are a lot more and more innovations in the space of sanitation that are looking at protecting public health and the environment and obviously preventing fecal sludge contamination to end into the groundwater. So this system has been developed by University of South Florida. They have been doing different stages of testing, but it shows you that there are options of treatment on-site instead of collecting it and then having to be emptying and treated. And also producing clean water for reflushing and some potentials for hydroponics for plant growth within the system. This is another type of system that is looking at more of a community-based type of treatment where there are treatment tanks underground looking at some biological form of treatment ending with electrochemical treatment that is purifying the water and then it kills off the pathogens and the water could be reused for flushing. And of course, this is running off the grid. So all of what you see on the top is solar panels. This is another example. It's the ESOS smart toilet sanitation, which has been developed by one of our professors here, Professor Barjanovic etiachi and his team. And this system is actually designed for sanitation in emergencies. We know that this also is quite vital for provision when we have natural causes like earthquakes or tsunamis. The provision of safe suitable sanitation solutions is quite important to prevent groundwater and environmental contamination and of course protecting the public health. Another option could be container-based sanitation, which is looking at the treatment of all the excreta that has been safely collected, emptied, transported and treated and potentially looked at safe disposal options. So for all these innovations, there are also different types of ISO standards or different types of other standards that are looking at different parts of the sanitation service chain to be able to treat, to be able to ensure that all the management and the technological solutions that are implemented are looking at the safety and the public health aspects and the environmental protection. So then we don't have these kinds of situations that we discussed earlier. And of course, the one important aspect that we could do is looking at the provision of more sanitation experts, because this is really needed in order to achieve what we want for SDG 6.2. Thank you. Thank you very much, Konstatina, for your very informative presentation. I personally like the technologies that were presented. I hope we will have some time to discuss later. And without any further due, I would like to invite our second speaker, Dr. Jan Willem-Foppen, to have his talk, please. Yeah, thank you very much. Let me try to share my screen and then open my presentation, which I'll put on presentation mode. So I think everything is clear now. Yeah, fantastic. Okay, so groundwater pollution from wastewater infiltration. I will be talking about that. And then let me just try to get rid of one bar here. I cannot really get rid of the bar. Okay, so I will be talking about sub-Saharan Africa. And then one particular example, which is the voice of three area in Kampala. Kampala is the capital of Uganda in eastern Africa. I will just have a look at what we have done in the last, roughly in the last 10 years, not continuously, but we have done some studies there. And first of all, I will just look at the area. Then at the situation concerning the infiltration of wastewater surrounding two pit latrines, just two pit latrines. Then I will try to scale up a bit and look at the shallow aquifer and try to give you some of the complexities when we want to scale up. And then the situation comes even more complex. The moment you look at the entire system, which is composed of a shallow and a deeper aquifer. That is with respect to chemistry. And then I will just briefly also look at the microbiology of things. And then finally, we are going to look at groundwater management in this particular case, which is not an easy thing to do. Let me see whether this works. No, not yet. Yeah, now it works. Okay, so the study area is here. In fact, we are here a piece of Kampala. Let me see whether I can do something about the pointer options. So here you can see this laser pointer is that clear. Yeah. Okay, good. So this is a hill. This is a hill. And this is another hill. And here we have a valley. And in that valley, which used to be a former swamp, we have a couple of slums located and we have here we see here boys at three. And the case study concerning the two picture trees is focused here in this part of boys. So I will first focus on that part. And then later on, I will try to look at a bit of a larger picture and mainly focus on this cross section. And little square that you just saw is a few one to two square kilometers and here you have an overview of point source pollutions, which are pit latrines, solid waste open dumps and animal feed lots. Beware, this is already quite some time ago. So this is, you know, fairly old information. The solid waste dumps are nowadays they are sort of gone. The animal feed lots they are there, but not that much, but the pit latrines are still there so this here this square is 250 by 250 meters. So you can see that in this slum area, the valley between the hill here and the hill there, there are many pit latrines in this slum area. They are usually in open connection with groundwater. So how does it look. It looks like this. So here you have a toilet. And below that you have a pit latrine and the pit latrine is actually raised because there is hardly any space for the pit to to to be there because groundwater levels are quite shallow so therefore population raises the pit in order to you know to be a little bit above the groundwater table. Here you have another example of a toilet and below the toilet you have a raised pit latrine. This structure looks a little bit better. It even has a door and this structure doesn't really look very well maintained. So, if we just look at all these pit latrines that most of them are like this. So here we have an overview of what do we see in terms of sanitation facilities we have usually the traditional pit latrine. The traditional pit latrine predominantly more than 80% of the facilities are the traditional pit latrines, like in the example that I just show most of them are also raised. So here is a little cross section so this is just a few meters like 10 to 15 meters. And here we have also a few meters of elevation and here we have these two online pit latrines that I just talked about. This is a scale so they just put in there just you know for your reference we have here a water table that is in blue and this here is the shallow aquifer which is composed of loam and clay sand and then below that shallow aquifer we have a layer which is a few meters of stiff clays. We have a number of piezometers there upstream of the facilities and also downstream of the facilities. And we monitor ground water quality. And what we saw was an overview like this so here you have the pit latrines. And you have here the results of the piezometers in terms of stiff diagrams that we use hydro geologists as a way to represent ground water quality. What you can see is that upstream the stiff diagrams are fairly small also this one here is fairly small, which tells us that the amount of ions, canines and anions are not that huge. When we look immediately downstream of the pit latrines, we see that concentrations of most major canines and anions really increases a lot and this little peak here tells us that there is also a lot of nitrate in there. When we look further downstream, we see that some of these ions are still in there, but the nitrate is already gone. And we were wondering what is going on here. Well, now we have to look at it from a little bit of another perspective and we just have to realize that this slum area used to be a marsh composed of papyrus. And that papyrus is still there and it's still there in oxidizes and when it does that it produces anaerobic groundwater and we have anaerobic groundwater. One of the first things that happened there is that nitrate is reduced it is it leaves the aquifer as nitrogen gas. And that's exactly what we see. So here we have our study area where we had these two pit latrines. Here you have some nitrate but immediately a few meters, a few meters below or downstream of the pit latrine. We see that the nitrate is already gone and there we have manganese entering the seam nitrate is gone. And then here we get even very strongly reducing conditions whereby we also have the production of island two plus. Still phosphorus is there as a result of the infiltration of wastewater. But the nitrogen is already gone. Mind you this here is a bit of an exaggeration. This is only a few meters in terms of vertical extent. So here you have the aquifer and there below it you have that little stiff clay confining layer. So this is the situation with respect to the shallow aquifer. It's the pattern that we get here is it's complex. You cannot just say that when when wastewater infiltrates nitrate is produced and that's it. Now, depending on local conditions that nitrate can be reduced, you don't see nitrate anymore and the effect is a little bit. What is exactly gone doesn't mean that all the ions from wastewater are just gone. We just talking about nitrate pollution in this particular case. The previous picture was here. And this gray thing is our stiff confining layer. This is the alluvial sands that we talked about. And now we look at the bigger picture. We have also springs here and these things are not unimportant because they receive groundwater, which is aerobic. It has a moderate specific electrical connectivity. It has very high nitrate concentrations. The pH is nice. It's fairly acidic and the residence times are quite limited. When we go even further up here. So there's also some, what is it, people are living there and not that many, but there are definitely people living there. But what we see here is that we have, again, anaerobic water. Sorry, we have aerobic water with a low electrical activity and their nitrate concentrations are again relatively low with your low nitrate concentrations. Here we have a situation whereby we have very high nitrate concentrations. Here the situation is a little bit mixed whereby we have high nitrate there and low nitrates there as a result of anaerobic groundwater. So the take home message here is that it's complicated and you really have to know your groundwater flow situation in order to be able to understand what the effect is of wastewater infiltration on your groundwater quality. So, focusing on these springs where a lot of nitrates are there. Here we have such a spring and you can see that these springs they are used for drinking water. So the people living there, they use this water because it is for free. So they don't have to pay a lot and they really use this water massively. So this is just one spring. You see people, mainly kids and women, they are queuing up to get some water from that spring. Here we have another spring, same situation, people are queuing up to get that water, that water which is contaminated. Now we have just seen that it is contaminated with chemicals but when we just look to the microbiology of things, we see that E. coli as an indicator of fecal contamination in groundwater is widespread. In addition to that we did some sequencing of DNA, of viral DNA and we saw that in that groundwater there are a number of virus families that must come from above ground hosts like frogs and mice and rats and cows and horses, monkeys and humans. So they all live above ground and we see that those virus concentrations are also found in groundwater. So there is a direct link not only from sanitation but from land use as such and from the creatures living on that land service to groundwater. In addition, we also noticed a couple of pathogens that we have not seen before in groundwater. So the pathogens as such are not new but the fact that they were detected in groundwater was fairly new. Herpes is there. We also saw papilloma and we saw pox virus. All of that you can find in a publication by van de Volsberg et al. in ESNT water last year. So okay, having seen this, this sort of on-site sanitation and using an aquifer to get rid of your wastewater is maybe okay but if downstream users use this groundwater for drinking water then there is a problem. And that problem cannot be easily fixed. It's very complex and there's no single solution to that problem. And I think this is the definition of a wicked problem, which is known in literature, and then here wicked denotes the resistance to solution rather than evil. I've just got this from Wikipedia. So we looked at this wicked problem in the last couple of years in a project focusing on transition management, which is especially meant to look at wicked problems. The ultimate proposition in transition management is that front runners take an influence, a transition, when they are given space to do some thinking and to undertake some action. The definition of TM transition management is a stepwise participatory process, bringing together front runners and change agents to create a vision. There are strategic transition pathways and rooms for action to ignite and influence transitions. So we experimented with that transition management in a number of areas in Sub-Saharan Africa in the last years. And more, so I will not go into details of that, but more on this is on this website, tgroup.science. And there is a video there. There are more videos with one of them. I just want to highlight here. You can find it on the website, but it's also in here. So let me try to, can I now run this video? Let me just have a look at that. Do something about my, yeah. So I just have a 60 second footage of that video that I would like to share with you. In Boise, groundwater pollution mainly originates from the surrounding hills, like uphill Makarere, where wastewater pollutes groundwater, which slowly flows over a long period of time into Boise. All findings show that ground water is contaminated. As you go from the hills down to the valleys, it becomes more contaminated. The teams organized dissemination meetings to inform the communities about the results of research and started to select actors for the organization of transition arenas. The selection is a key part of the transition management. And we were looking at those who are natural leaders, those who are active in doing something for the community. The transition arenas focused on the structuring of local problems, self and collective responsibility, envisioning and developing short, medium and long term actions to solve the problems in Boise. My pointer options, let me go back. So more of this is this website if you want to have a look at that. So yeah, now I come to my conclusions. So wastewater pollutes groundwater and we all know that chemically and biologically. And the fate of the pollution depends on aquifer characteristics and the flow system. So you cannot just separate those two. You have to take into consideration the aquifer characteristics and the flow system. If it is then the nexus between on-site sanitation and drinking water, that is a problem which I think we should consider to be a wicked problem. There are many ways to treat wicked problems and one of these ways is transition management and that may be used as a vehicle to sort of together to unravel that wicked problem. Having said that, I thank you very much. And I think along the floor is open to questions. Yes, thank you very much, Jan-Willem, for your very interesting presentation. I am sure that a lot of our audience will find the presented content from both speakers very, very interesting. So so far we have heard about the mechanism of pollution from sanitation. We have heard also about the wicked problem and the links between drinking water and sanitation and how difficult it is. We think about also very concrete technologies for improving the problem. So I'm very much looking forward to the discussion and the Q&A. In the meantime, I have collected quite a few of the questions from our audience and I will share those questions and I will post that to both speakers and we will address them one by one. Just a moment, I will put them up. Yeah. The first question is from Wambui. The question is interesting to see the onsite sanitation, very applicable for a country like Kenya where 60% of universal coverage is supposed to be onsite. The only challenge is affordability. I would love to have one of our speakers to comment on this affordability of these services. Can I have a second step in? Yes, please. Thank you, Wambui, for your comment and question. Yes. The second question is that often we look at the basic form of solutions that are being the cheapest, but in reality it becomes more and more expensive when we have to think about the whole management through the sanitation service chain and how to provide these systems, to manage them safely and how to ensure that they perform safely. So, yeah, I agree with you, but then that's why it's encouraging to look at options maybe because what I was trying to say is that we look either onsite sanitation, basic options or unsafe sanitation or sewer. And what is in between has been left for a long time without looking for solutions. So maybe it's time to try to look for more and more innovations or joint solutions that could be affordable but at the same time safe and prevent from contamination of the water resources. Thank you very much, Konstantina. I don't know if Jan Willem would like to comment on this or we can move. I have actually a question when I see the challenge of affordability, then the question to Wambui is as far as I'm concerned, what is then the alternative that you have? Is that an open defecation? Is that the alternative? Yeah, I think this question is to be with Wambui and maybe we will hear further comments on the chat box. Yeah, let us stand in the meantime, move on from a question for a question with Mohammed Yastia. He says groundwater levels are declining worldwide and are there implications for wash and sanitation services that we need to prepare for? Would you like to reply to that, Konstantina? Yes, I can go for it. Yes, we need to look at options to prepare for and that's why I was saying that we have been looking at the sewered sanitation as the cure for our waterborne diseases, safety. But unfortunately for many water scars areas in the world, this cannot work because gradually the water is reducing. So obviously this is not going to work and then we need to look at either options that are reusing water. So if it's a flush based system to reuse the water instead of discharging it or to look at the potential of using dry systems. Again, everything needs to be weighted. We always have to account for the available resources, the investments, but then also we need to be mindful what we can take because some of these innovations that I've tried to touch on are looking at resource recovery, for example. So if in this aspect we look at the excrete or what is produced as a resource for is a valuable resource that we can use for energy or reuse water or nutrients for agriculture, then things may change because we can also incorporate it into business models to recover some of the investments. Yeah, thank you. Would you like to add anything to that, dear Jan-Willem? Yeah, the aspect of groundwater levels that are declining worldwide. I think that is true. I can just add here, due to over abstraction, there is a lot of groundwater level declining going on worldwide, not everywhere. It is of course confined to areas where groundwater is heavily used. So, yeah, I think that is as far as I'm concerned my response to the aspect of groundwater levels that are declining worldwide. Yeah, thank you very much. Let us move on to the next question also from Wambui. It says the boiling water 96% there here 25%. I guess it is referring to some of the statistics that Konstantina presented and the question was the link on disease. Yeah, I mean, as I mentioned, this was a master's student study, so it has been quite limited because he had a very limited time for his data collection. So, obviously the data was based on questionnaires from households, but they have been unlimited questionnaires. So, also often, yeah, we need to go back and reanalyze these data, but sometimes they would be, maybe the meaning was that what they used to purify water is boiling, but in many cases they may not use all the time the boiling, maybe at household, but if they're on outside somewhere, they wouldn't use any form of pretreatment. So, yeah, this is about to look at a relationship between the data that has been collected. But the most important is that a lot of the households reported the real diseases, which was also quite, it's usually quite linked with E. coli availability, which could be due to improper sanitation or having some of the excreta reaching somehow to the groundwater facilities. Yes. Let us move on in the meantime with another question from Mr Rainier Velman. He says, has there been consideration for accepting the groundwater as it is without contamination, but to focus on the use of treatment options for the water, especially household water filters. The groundwater quality can be tested, but it will never be feasible to continuously monitor its water source. Secondly, a lot of the options are quite costly. So the question is whether it is feasible to apply on a large scale, especially in lower income rural settings. Do you have thoughts on this? Shall I try to respond to some of this? Yes, please, yeah. So the term accepting the groundwater as it is is a very, very difficult. And also, what is it? It has a lot of dimensions. I think when we look at the urban poor, so just focusing on the case that I discussed. They accept groundwater as it is because they have no option. And any treatment that you do will cause them money, which they don't have. That's the problem. There is so little capital in these areas that it is difficult to install or to experiment with any type of treatment. But cooking the water, for instance, is just way too expensive because you have to get the wood from somewhere to cook your water. People don't do that. It's just too expensive. And then there are the authorities. And in Uganda, the authorities, and now we are getting into a completely different discussion, the authorities, they want to shut down the springs that the urban poor use. Because this is one of the boundary conditions for getting funding from institutes like the World Bank. Because everybody knows that this groundwater is heavily polluted and people are drinking this. So Kampala has tried to close down a few of those springs and there was, and there was a rioting because there is no alternative. There's just no alternative. So the word accepting is has a lot of implications and it's not that simple. It has many different dimensions. Yes, groundwater quality can be tested. And it is never feasible to continuously monitor each water source. That's absolutely true. Yeah, so I mean that that is that is the case. We know that groundwater is not moving that fast. So if you monitor groundwater quality in your monitoring network, then you should have a you do that fairly properly then you should have a good idea of what is going on in terms of groundwater quality and also the use for drinking water. Actually, Rainier, you just mentioned it yourself. A lot of options are quite cost. It's the cost. So we have been using filters that were installed in a metal container with PVC in it. And there were a couple of layers of sand and gravel and things like that and it all worked well, but the local population was more interested in the iron of the filter than anything else. So it's it's it's complicated. It's just complicated. So, yeah, I mean, there is a reason why this still is a huge problem worldwide. So that's my response. Thank you. Thank you very much, Jan Willem. Let us move to the next question from Saka Mohammed Rafiq Alam. I noticed that we are running a bit out of time and I asked for our speakers to have a bit more extra time for this, that we address some of the remaining question is it okay with you Jan Willem and Konstantina. I'm fine. Yeah, yeah, we can use five minutes. Yeah, let's take another five minutes. Yeah. In Bangladesh, we have had an experience of having sanitary latrines without any type of lining inside a pit in rural areas using cement rings and slabs that subsidize rates by the government. It is popular. Would you please mention the coasts and required space for sanitary latrines you have presented in the first presentation. So I guess this is to Konstantina please. Yes, thank you. I'm not sure which sanitary latrines I'm not sure if it's the innovations or any other conventional systems. But my take on this is the cost would vary depending on the local conditions and the type of systems that are adopted to the local customs. So in, I really can't give a cost of a conventional pit latrine I can say in South Africa used to work in South Africa for a while. It was to be the equivalent something between $150 to $200 the full construction. But I guess this really depends on the on the place for the innovations. The ones that I have presented was just to trigger, you know, thinking and discussions that we need to look at some alternatives. But what I presented to you or were systems that have not been mass produced yet and they have been installed and being tested in different places. But of course, as as we know, through the different stages of technology development, until we get to a mass production, the costs are really not so great. So yeah, they're quite high because there are sensors and so so these ones would not be that cheap. But the good news is that I think for the next two to three years, some of these innovations are going to be available on the market. And the hope is that this would bring the prices down. The inspiration behind some of these systems has been that they would be at low cost, low enough to be affordable by anyone. And especially the operation and maintenance costs to be something like 0.05 US dollar per capita per day, which is quite low. But whether we are getting there yet, not yet, but slowly, I would say. Yes. Thank you very much, Konstantina. I have a next question from Mr. Joseph and then found out and often, Joseph often encountered a situation where request being made for designs of facilities, citing lack of know how and money. But often these facilities are already being present in the countries. He thinks that the main reason for slow progress is that the governments and local authorities are often not suffice sufficiently committed. I think we motivate these governments and local authorities to make more progress. Well, the best way you can go you can go after that. I think you know what we saw. So I'm just referring to my experiences with transition management. And I'm not here to advocate transition management. What I'm trying to my point is actually, if you can mobilize local communities. Then, in the case of Uganda, then institutes will start to become committed. So if local communities directly start to talk to, let's say local governments or local authorities, and they have, and they have well argumented discussions together, then these governments they start to become committed. So, I think that that would be my response. So, not sufficiently committed is absolutely true, but it is. It is what is it. It depends. So there is, there is a dynamic that you can that you can induce by giving the local communities a voice. And then something really good can come out. We saw that in these communities, whereby there was so much distrust between the communities towards the local authorities, but after some time we saw that they really started to work hand in hand together. And that that was really an absolute good part of of of of in this case transition management, but there are many different ways to mobilize communities in proper way. Yeah, and now I can add here is what is what is the biggest motivation for a governmental local authorities. I think, well, it's it's for many other stakeholders representatives, but it's it's money. So, speaking about how much it costs, having these problems related to improper sanitation open defecation not safely managed sanitation related to groundwater management. So this, if it's put into numbers, cause a lot of money to local governments and local authorities to deal with treating diseases hospital placements people missing out of work, etc. So, if it's possible to show this kind of balance and evaluation on what would be the saving in what they in their investment per year could be one way. And so what I'm trying to say is that it's often how how the information is presented. And of course, yes, there is a need of all the stakeholder engagements we need the local communities to be fully engaged, we need the private sector. We so speaking about looking at options of how can we turn the wheel and how can we look at resource recovery or business models. Some of these, the provision of these systems could be more simplified but still safe. So this could be also a business model for selling and installation and and maintaining so yeah, this is my take on this. Thank you very much, Jan Wilhelm and Konstantina for sharing insights on this question. We have one remark and two questions and I, for the sake of time, I think, if I may ask you to keep it brief with the responses, and then we can close the webinar on time. So we have a remark for Mr. Dinder Babatunda from Nigeria. He says Nigeria just launched a center on integrated national environmental health surveillance system through the federal ministry of environments strictly on water sanitation on hygiene, waste and air quality. I would love to partner as we got to technology transfer and capacity development for health workers. So I think this is a very nice remark and very positive development in Nigeria. Please feel free to get in touch with our speakers today. Yeah, send us an email. Yeah. Yeah. And maybe you can provide your email in the chat box that would be fantastic. The next question is from Tess Faye. Thank you very much, Dr. Jan, in order to track and trace these pollutants and take some corrective actions. It is possible to make use of time series data regarding what the level and what the quality in conjunction with numerical modeling in the basic level it is needed and how to do that. Yeah. Let's say I think you're absolutely right. So it starts with a monitoring network to understand how your groundwater system is responding. And also to understand what the ground water quality and let's say the mass transport in your aquifer system is. And if you want to do a numerical check at a basin level about your water balance and how ground water flow patterns have developed. Absolutely. Super nice. Yeah. Yes, thank you very much. And so we have a next question, which is the last one before we close the webinar. I am a chemical engineer from Iraq. In my country, we do not have any solution of wastewater from homes. Is there any simple solution that we can conduct? I suppose to understand the situation and to see if it's possible to install these solutions. Yes. So what I was going to say is that I touched on the part which concerns on-site sanitation. So, of course, there are many countries where sewer sanitation has been installed and it's widely used. And this is something that I didn't include in the presentation because of the time and the focus. But what we follow is the citywide inclusive sanitation approach. Meaning that if there are sewers that have been already installed and this is working or operational. So then it doesn't mean that we have to remove now the sewers and install some appropriate solutions. It means that if there is a part of the population that has not been yet covered by any form of safely managed sanitation service, then we have to relook again what is the cheapest and the most convenient option. So when I say cheapest, of course, maybe some pit latrines could be the cheapest option, but with time they may not be the most convenient option or maybe not the most dignified if it's just simple pits. So we're speaking about improved sanitation systems that could be on-site, but they could be a lot more pleasant to use. So it's about the combination of all the solutions, but of course, yes, it is possible to look at all the options. There are simplified sewers, there are many options if you want to look at. But the main point is to address the not safely managed sanitation because this is directly linked to polluting the environment, including the groundwater facilities, which also, as we saw, is related to spreading of diseases and a lot more serious complications. Thank you very much, Konstantina, and thank you very much participants to share the questions. I have a question. Yes, Jan Wilhelm, yes. I have seen that in the chat there are a lot of emails going around. Are you harvesting those email addresses? Okay, thank you. I will collect all the, yeah, I will mention that also later. I'll collect all the emails and make sure that we have all those emails and the recording will be shared also afterwards. Okay. Yeah. So with this, I would like to thank you very much Jan Wilhelm and Konstantina for a very informative and inspiring seminar. I'm sure the insight and the experience shared today will be of much interest for many people working on groundwater sanitation. And I see that there are a lot of emails and interactions to be picked up. So it's great, fantastic to see. We wish you a lot of health and joy in continuing your great works. I would also like to thank our participants very much for your kind attention and interactions. We will keep you posted about the upcoming webinar podcast and blog articles within this initiative between IG Delft and the Water Channel. Last but not least, now that 2022 is getting behind us slowly and 2023 is approaching. I would like to invite Miss Maria Laura Sorrentino, Alumni Relations Advisor from IG Delft to give some season greetings and to close our seminar. Please, over to you, Maria Laura. Thank you very much. And thank you very much to all attendees and to our greatest speakers today for their collaboration. It's a great pleasure for me to organize with the Water Channel all the online seminars this year. And we will hope to continue next year with other topics and interesting lectures. Thank you very much for your attendance and season greetings for all and all the best wishes. My colleagues are coming back. Have a great December and fruitful new year. See you next year. Thank you. Thank you. Goodbye everybody. Goodbye everybody.