Sounds like overkill?
I guess you don't read about the people that get sick and die from E Coli....
The reason people don't get E Coli from wells is because wells are properly constructed with steel or PVC casing set into bedrock. The wells have water tight, vermin proof well caps and people have their water tested at regular intervals to be sure the water is potable (safe to drink). The few times I have seen EColi in wells is because the casing rotted, the wells were old pit wells with bad well seals or there have been animals dead or alive in the wells.
What we are talking about here is not the same as a well. It is a freaking hole in the ground with water seeping out it. It has no protection from surface contamination. There is no way to know whether there is any subsurface connection to a sink hole that might have a dead cow or deer in it. And truth be told, if he had the water tested today and it was bacteria free, that is no guarantee that 3 months down the road it wouldn't still be bacteria free.
True many people in third world countries drink shit water, but they have built up an immunity to it over the years. That's why the elderly and children are especially prone to getting sick from, E Coli, they don't have the resistance.
UV lights are rated for gallons of water per minute based on the amount of water per minute you are using. For example you don't want a UV light rated for 10 gpm if you are going to be using 20 gpm because there won't be enough exposure time.