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Q. Do I need to install a pressure-reducing valve in the water pipe coming into my house? My house is 25 years old and I’ve never had a problem with pressure. A plumber recently determined that my water pressure was 80 pounds per square inch (psi)--far a bove the normal 60 psi--because the county increases line pressure continually to meet the demands of new development. He said that the desired 60 psi could be maintained by installing a pressure-reducing valve in the water line just after the cut-off va lve where the water pipe comes into the house. He quoted what I thought was an extremely high fee to install this valve.
Are pressure-reducing valves necessary? Do you recommend their use in all city/county water connections to avoid the potential damage that could result from too-high water pressure?
A. You didn't mention how much money the plumber wanted to install the pressure regulator valve but I would indeed recommend one. Your homeowner’s insurance may cover you for a pipe burst but I can assure you the cost of the valve is worth avoiding the h assle of dealing with the household water disaster of a burst pipe. The over the counter cost for those valves is in under fifty dollar range and the rest is the price of installation.
Pressure regulator valves are now being installed in all new construction connected to municipal water supplies along with a small expansion tank near the water heater which, if you get the valve, you should also have installed. The reason behind the val ve requirement is obviously protection from high line pressure and the occasional pressure "spike" caused by a sudden shut off of a large water usage, such as a fire hose shutting off somewhere along the main water line.
The higher water main pressures are in response to the required pressures for the fire suppression sprinkler systems now mandated for new construction of condos and townhouses. Some municipalities nearby are requiring sprinklers even in new single famil y dwellings. The pressures I see on those systems are routinely between 100 to 125 PSI.
The pressures you quote in your house are on the high side-- domestic water pressures are desirable in the 50 to 75 PSI range for a number of reasons. You don't want to blow your dentures out of the glass when you turn the sink faucet on, get a pressure rash under the shower, have the little valve in your toilet hemorrhage due to too much pressure or a have a water heater tank weaken and develop a seam split and leak all over the joint-- just a few of the consequences of too much water pressure. I've e ven read that you don't want water traveling faster than 8 feet per second inside your copper pipes-- which high pressures will do-- for long periods of time as the friction will eventually wear the pipes out!
The small expansion tank, which is normally installed near the water heater tank, that should go along with the pressure regulator valve is used to absorb pressure build-ups within your plumbing system as the pressure valve is a one-way valve-- in-- and conversely will not permit high household pressures to back out the main water line as they would without the valve. Let me explain. Let's say you have just taken a 15 minute hot shower and your water heater is 25 feet away from your shower. You turn of f the water, dry off and leave the house. All the fixtures are now off.
Cold water that entered the water heater tank is now being heated and expands slightly. The water line that conveyed the hot water from the tank to the shower heated up to at least 120ºF while you were showering. Now the pipe and the water standing in i t are cooling off down to whatever the house temperature is. The copper of the hot water pipe is shrinking slightly in response to the lower temperatures but water is non-compressible. So the pressures in the house piping go up with this combination of f actors and the water is looking for a place to go. I've seen data of measured pressures of over 400 PSI in unrelieved systems and that will indeed cause problems. The pressure tank absorbs those pressures and everything stays within accepted ranges. Ex pansion tanks are in the $100.00 neighborhood plus installation. I would get that pressure regulator valve and expansion tank and consider the cost cheap insurance.*end