From what I read and hear about datacenters, there are not too many server rooms which use water cooling, and none of the largerst datacenters use water cooling (correct me if I'm wrong). Also, it's relatively easy to buy an ordinary PC components using water cooling, while water cooled rack servers are nearly nonexistent.
On the other hand, using water can possibly (IMO):
Reduce the power consumption of large datacenters, especially if it is possible to create direct cooled facilities (i.e. the facility is located near a river or the sea).
Reduce noise, making it less painful for humans to work in datacenters.
Reduce space needed for the servers:
On server level, I imagine that in both rack and blade servers, it's easier to pass the water cooling tubes than to waste space to allow the air to pass inside,
On datacenter level, if it's still required to keep the alleys between servers for maintenance access to servers, the empty space under the floor and at the ceiling level used for the air can be removed.
So why water cooling systems are not widespread, neither on datacenter level, nor on rack/blade servers level?
Is it because:
The water cooling is hardly redundant on server level?
The direct cost of water cooled facility is too high compared to an ordinary datacenter?
It is difficult to maintain such system (regularly cleaning the water cooling system which uses water from a river is of course much more complicated and expensive than just vacuum cleaning the fans)?
