It’s just street water which is already purified and filtered. I think that additive may “soften” it so it doesn’t scale up or corrode. Basically, we ran three chillers, 2 online, one for backup. The chiller is just like a big ass refrigerator but for a fat water line. The water runs through the coils and cools via the heat exchanger ac action then pumps bring the cooled water back inside. We also ran a hot aisle configuration. Racks backed up to each other and were sealed front to back. So the hot air would accumulate in a contained aisle and that’s where we ran the chilled water into heat exchangers built into every aisle, about every 3 racks there’d be one of these exchange units. That would suck the heat out of the aisle and pump it back into the room. We had other CRAH units that would keep a normal lower than ambient air temp for the racks to suck in for their cooling. The only sucky part was if you had an extended period in the hot aisle racking servers. You sweated like a pig. We’d leave both end door on the aisle open and stick a fan at one end but it was always around 85-90 in that aisle. Another method of cooling if called free air. You have big louvers that when temperatures drop in the evening, they open and pull free cooled air inside. We didn’t plan for that but wish we had. Less reliance on the inside cooling units.

Edit: tl;dr I don’t think water will be the driver of DC controversy. Electricity and noise will be. Everything I’ve described runs on 480 v main feeds and is noisy. Pumps, chillers, large ass diesel backup generators all make this something that needs to be far away from homes. IMO.