I don't see why they wouldn't just dig a hole or find an empty space instead of crapping in their drinking water.
Is that even what they're doing? Do they have no toilets, or are they directing the waste lines into their water supply?
Just giving people things doesn't work. You have to teach them. If they aren't advanced enough to understand on their own then it needs to be explained to them. If they still don't understand, then good luck and goodbye.
When the French left Haiti, they left them with roads, modern (for their time) buildings and systems in place that they merely had to continue to follow. They were incapable and now live in hell.