As a society, we Americans pour quite a lot of water down the drain. Then we get fresh water from the faucet to water plants, the lawn, or a flower box. Most of the country is experiencing drought. My cognitive dissonance is massive.
Okay, sure, you rather sanely wouldn't want to drink water that's been in your sink with the raw meat and dirty dishes. Plants are less picky. If your water is full of bacteria, they think that's awesome, it'll bring them more vitamins. If it's hard, even better, free mineral supplement! It's warm, no biggie there, either. It's we animals that worry about that kind of thing.
Greywater systems that recycle safer sources of used water to water a lawn or garden have existed for years, the main obstacle being legal. See, plumbers used to install septic systems really close to the house out of sheer laziness, and then when something went wrong with the septic system, the homeowner had a massive flow of unmentionable straight into the basement, which was bad for the owner's health. And whatever plumber was called in to fix it. So the universal plumbing code requires all septic systems to be a certain distance away from any house, and numerous safety features that don't play well with greywater.
However, in an increasingly thirsty world, more and more municipalities are forced to reconsider these rules, lest they be forced to pay for expensive treatment plants on increasingly stressed budgets.