 You may have read in the press about medicines like antibiotics and the pill being found in rivers and lakes. And even in drinking water. Maybe you've been told you don't need to go to the pharmacy anymore. Why there's a pharmaceutical cocktail coming right out of your tap? You may have even heard the rumour that pharmaceuticals in drinking water are making men less manly than they used to be. So what of all this is true? Pharmaceuticals have indeed been detected in the environment and in drinking water. However, the stories about medicines in tap water affecting people's health are baseless and far from the facts. But what are the facts? Detection methods have improved enormously and we can now measure substances at levels up to 1,000 times lower than we could only 15 years ago. And yes, these improvements have shown that drinking water sometimes contains very low concentrations of pharmaceuticals. So how low? Well, if you wanted to consume the 400mg of a typical ibuprofen pill, you would have to drink around 200 million litres of tap water, which makes about 40 Olympic sized swimming pools. There still are knowledge gaps on this topic, but in 2012 the World Health Organization concluded that at current levels appreciable adverse impacts on human health are very unlikely. So as far as drugs are concerned, your drinking water is safe. But there are risks related to pharmaceuticals in water for animals in rivers and lakes. For instance, female hormones in the pill contribute to feminisation of male wild fish and low concentrations of an anti-anxiety drug have affected the behaviour of carb, making them less social and eat faster, which makes them more vulnerable to predators. The unpredictability of these effects was shown in Asia. Vultures ate corpses of cows treated with dichlofenac and died as a result. Populations fell by over 90%. So clearly, it's a good idea to reduce the input of pharmaceuticals into the environment. But how do human drugs get into the environment in the first place? When you apply medication on your skin, part of it will always wash off. And when you take drugs, some is absorbed or changed by your body, while some is excreted unchanged. It all ends up in the wastewater treatment plant. There are around 3,000 pharmaceutical compounds on the market, and treatment plants deal well with some and not so well with others. So some drugs always make it into the rivers, and some remain in the treatment sludge, which is often used as fertilizer in agriculture. And what is being done about this? Research is closing knowledge gaps, such as the long-term impacts of low drug concentrations. And the European Union has started to regulate the issue. But you can also help by doing three simple things. First, never dispose of unused medications in the toilet. Second, ask your pharmacist how to dispose of unused or expired medications. In many countries, they're collected from the pharmacist and burned at high temperatures. And third, you should avoid exaggerated self-medication. Better just take medicines when the doctor tells you to. Remember, pharmaceuticals leave our bodies and may have a larger impact on the world around us than we know.