I like the idea!
With all we do already to filter I’m trying not to spend much more on it. My well water ruins clothes, and was ruining pipes and all that. Nice softener and filters fixed that while RO is my drinking/cooking. Like you said - probably don’t wanna drink it and your right. They test every well and it’s on record somewhere. Arsenic is present in them all. Levels rise and fall throughout the year so you never really know how much is in there. Some Michigan wells have actually poisoned people in other parts of the state.
Also rain barrels ftw. I have 200 gallons all spring summer and can store a lot inside too for a while but not enough for all winter.
I used to have 3 in New Mexico where this well pumped something resembling water. Even weeds weren't happy with it. Had 2 going at any one time. When one started getting slower than slow it got torn down and rebuilt. The water was totally drinkable. There's a very long history with slow sand.
"1892 A cholera epidemic strikes Hamburg, Germany, while its neighboring city, Altona, which treats its water using slow sand filtration, escapes the epidemic. Since that time, the value of granular media filtration has been widely recognized."
This is particularly remarkable since both cities drew their water from the same river.