I have always been a little leery of water-based cooling. Water being so close to mass amounts of computer equipment just didn't make sense. With all of the water cooled systems that have come out in past years I have become more curious, but still wonder if it has a place in the data center. With the extreme density that some racks can have, I suppose their is some practical purpose for it.
Jonathan Heiliger, CEO of Aperture Development explains that the cost also plays a large factor, depending on what the density being cooled is. In this Processor article he states... “Generally, it’s cheaper to spread systems across the data center floor or build additional data center space than deploy water cooling today.”
No matter what your opinion on water is, it is worth the extra effort to prepare for it if building a data center today. Check out the rest of what I found to be a very good article here at Processor