As I live in a wealthy and rainy area we have a centralised water system which requires constant monitoring. Which ever smart goals you set for the competition it’s best to take into account the income of the poorer people. One thing I am certain of is that there needs to be cheap monitoring of drinking water quality, such as old smart phones can do, which are being developed.
Appropriate technology solutions as interim technology until higher incomes make higher technology affordable, and exponential cost reduction.
As an aside the best way to deliver cleanish water, probably at lowest cost would be to make it rain. A couple of speculative ideas I have put forward under water from air. This would be an universal solution and the source of our drinking water. Chicno’s criteria are good outline for goals