 Hi, I'm Tom Scherer, NDSU Extension Agricultural Engineer, and today we're going to be talking about water quality in particular, the total dissolved solids. Now all water contains some minerals, dissolved minerals, and at low levels they're good for you, helps the body for all mammals, but when they get excessive, they become a real problem. Especially in the western part of the state, in the summertime, when water dugouts start to evaporate, they start to concentrate the minerals in the water and it can get to toxic levels for animals. So today we're just going to show an easy way to check an EC meter, electrical conductivity meter to see if it is reading appropriately to measure water supplies out in the environment. Now we're going to be using hand-held EC meters that look like this, which measure electrical conductivity of the water. More minerals in the water, easier to conduct electricity, and therefore there's a relationship between EC and the total dissolved minerals. And on these meters, it measures the conductivity across one centimeter, and there's two probes on here, as you can see, one centimeter apart. So to make sure that the meter is correct, or I've been reading right, we can do a simple test in your home using salt and distilled water. First thing you want to do is just measure out four cups of water to put in a bowl, and you want to do it accurately, so I'm going to get down here and just fill this up. It's on a level surface, so I can see that I got just about exactly two cups, and so I'm going to measure out another two cups. So now we've got four cups of distilled water in here, and to that we want to add one quarter teaspoon of salt, level it off by shaking, and then just dump it in. So we're going to mix up the water, make sure that all the salt is dissolved, and we'll let it set for a little while to make sure it's finished. So then I want to check my EC meter, and on this type, I want to make sure I set the multiplier to .76 so that it gives me an estimate of the total dissolved solids in the water for natural water. So on this one, if I just hold this on and let it up, and I go down, it has these different settings, but I can go down, and at P4 you can see the multiplier set to .76. Every meter does it a little bit different, but you can set this anywhere from .5 up to one if you wanted to. So since that's set, now we'll go into reading mode, and right up here it says TDS. So now if I just stick it into the water and swirl it around, you can see it's reading about 2.54 parts per thousand. If it was reading in, if your meter or another meter was set to read in parts per million, it would be 2,530. And that's about right. And that reading, the way we measure it here, could vary anywhere from 2.4 up to 2.6, and that would be a good reading. Now one caution here is if you have a calibration solution from the manufacturer, I would recommend that you follow their procedure to calibrate your meter. But if you don't have that, or it got lost, or it's old, or you changed the batteries in your meter, or you dropped it, which is pretty common, then I would just mix up a salt solution like this and check it real quick to make sure that it's reading properly.