The only way I can read what they wrote to mean that is if they are saying water costs $30-40 a gallon.

No, I meant exactly in the petrol sense. Darn americanims - you never know if gas is gasoline, or poison, anesthetic, or flatulence, or you're just being gaslighted.

Even if you’re driving a Prius and getting 50mpg, if you’re “driving all the time” you’re spending at least $100 a month in gas. There’s nowhere in the country where a water bill is $1000 a month unless you’re doing a lot of irrigation.

I read the comment as an overview of their utility costs—natural gas, not gasoline.

lol. What a first world problem to have. Sounds like a very solvable problem too (remove the pool then)

A sheet of plastic floating in the surface while you don't use it could help to reduce the evaporation. If is a big pool put some holes here and there to allow air access if somebody or a pet falls into the pool.

Some marginal plants strategically placed and Nymphaeas can shadow the water (reduce the amount of heat that reaches the water), but you would have a very different kind of pool then and they have their own maintenance issues.

If your area allows the culture of columnar cactus and succulents, use it near the pool to provide shadow. They will rarely trow anything into the water and may be beautiful to see by itself. Look for the less vicious species like Euphorbia or Pilosocereus azureus that are strongly vertical while young, refreshing to see (blue is blue) and will not pose any problem if cultured in a wooden raised bed. The idea would be to make a short wall using the cactus as logs placed a few dm apart to allow the wind passing trough. You will need to avoid the access to cats protecting the dirt with a mesh, aizoaceae, gravel or rocks. Allow a lot of space for the roots. A small pot will not really work.

Cactus or succulents allowed to grow on the roof or near the house will act also as fire retardants (but not fire supressors) as they accumulate water.