Template:Infobox Utility Pipe Valve can be used to restrict the flow of water through the pipes. As of Alpha-8, steam will come out of valves.
How to use
Water valves are placed on any size water pipes and have two states, on or off. When off the water will not pass through the pipe and when on it will. To turn it on and off just left click the valve and click on or off. The change takes effect immediately and does not create a job.
Trivia
You can use this item to shut off water in a riot or any other situation where it's likely for prisoners to clog the toilets or flood everything. This reduces repair costs somewhat.
Flooded areas also reduce moving speed and conduct electricity from machines or appliances so being able to turn off the water supply makes these areas safer and more accessible for the security and repair staff.