All it can do is measure resistance. For the price it sells for I can’t see it doing more then that. Nothing to actually tell what impurities are in the water, just that it’s not 100% clear water. Better to buy a water filter and filter it.

I would imagine you may use it to test when your water filter is getting clogged up and allowing things to pass through it. That is if you test the water from your filter when you first replace the filter element to get a reference point and watch for changes. But it still doesn’t say it can detect a bacteria or virus (the things you want to filter out.) I don’t know if they are going to show any resistance change in the water?