Tap water is pretty cool even in summer. Has there been any attempt to circulate it inside the house for cooling before running out to faucets and toilets?
This is, in effect, how the buildings in downtown Toronto are cooled.
They draw cold water from the bottom of the lake for drinking.
But before it goes to the water supply, they use it for chilling.
They are lucky to have a big cold deep freshwater lake right near the population density.
Jim