rainwater

Just in alternate dimensions which make our galaxy look like a drop of rainwater. We just can't see it.

Irrigation You mean like a rainwater barrel + some old rubber hosing? You can make one of those for probably $10 in parts.

So even if you control several ponds, if your neighbor keeps a bucket of still rainwater, you'll have mosquitoes.

Our overflow comes from rainwater overwhelming the system and not from excessive human use.

Or try your best to get running water or a rainwater catchment tank providing water to such a system. If I had any leverage at all with the officials building these, I would strongly recommend the solutions above.

Not to mention our practice of shunting rainwater off fields as fast as possible. This high-speed, high-runoff condition leads to soil erosion, failure to recharge aquifers, and really gives rise to the need for irrigation.

Corporations have even tried to make rainwater collection off of roofs illegal. They've succeeded. Offhand, rainwater collection is illegal in CO, UT, and WA, and may be in others, too.

Their native habitat consists of rainwater puddles held in volcanic rock, so the shrimposphere is probably fairly luxurious.

Most recently, there was an article that described different parking lot geometries designed to prevent rainwater that lands on the parking lot from making it out of the parking lot, carrying lots of toxic crap with it. I also learned recently about horseshoe swales, which collect runoff from things like tennis courts.

You've eliminated the fire and criminal issues, but now rainwater runoff is flooding the road and your neighbors' property, you're causing ecological damage by eliminating vegetation and animal habitats, and you're blocking sunlight from your neighbors' yards. And since you're not consuming local resources, that means you have no way to get to or from your property, so really, what good is it to you anyway?

I suppose there's some quite interesting details involved in how rainwater that falls into the mountains manages to find its way through a complicated series of pipes to come into my toilet whenever I press this button, but there are far more interesting things to think about, so let's leave those details to the experts. If a prophet of plumbing did show up to explain all the presumably-fascinating-to-someone details of how the city's water supply works then it would probably hold my interest for the duration of a half-hour documentary, but then I'd get on with my life with only a marginally-increased respect for the plumbers who make it happen.

How is this better than local rainwater collection? Rainwater is desalination, you just cheated and let nature do the expensive part. Heck, lots of rainwater is already collected in gutters/roof drains, but is contaminated when it falls on the ground instead of into a tank. For irrigation all that is necessary is to soak the rainwater in as soon as possible to prevent evaporation and runoff, since potability is not a requirement.