There isn’t undesired water or electricity sources available at anything like the scale the AI companies want though;

A solution doesn't have to be 100% perfect to be an improvement.

Lets take an example of what I would consider a fairly advanced Landfill energy management site. Columbus Ohio SWACO (Solid Waste Authority of Central Ohio) operates a commercial landfill gas (methane) recovery operation. Today that methane powers the municipal buses, garbage trucks, and snow plows (in winter). Excess beyond the city needs is fed back into the natural gas pipes and sold at commercial rates to residential, commercial, and industrial customers. They've been operating this successfully for 11 years already.

The operation currently produces approximately 3,800 MBTU of methane daily. A high efficiency methane power plant (at 50% efficiency) would generate 557 MWh of electricity daily from that. More than half a terrawatt of electricity is certainly in the small to medium sized DC.

Further, the landfill produces 26 million gallons of leachate waste water. This is only a fraction of the water an Open Loop cooling system uses, but its a current waste produce, and its already onsite in the exact same location as the landfill gas which potentially could be used to offset other water usage.

Again, its not a perfect replacement for the land, water, and power, but its a very significant offset. A number of Ohio landfills are doing much the same as Columbus, and some are even supplementing with PV solar overtop of the landfill. If a DC was built on the Columbus landfill, the roof and remaining land could be covered with solar PV, and the recovered landfill gas stored during high solar production hours allowing even more gas available for electricity generation in the non-solar hours.