Just as a idea, a roll away cover, true you cant dance on it, but no
one could fall in. Add a really good filter and chlorinate or otherwise
treat the water.

Someone mentioned peeing in the water.

Everyone should realize all water has been used befoire It just gets
reprocessed!

For toilets no trouble

for clothes washing who cares as long as the water doesnt soil the
clothes

showering is akin to drinking the water, of course ever go swimming in
a lake? drink well water? etc etc.

how much $ are you willing to spend on filtration?