Household Water Pressure Problems

 Household Water Pressure Problems

Sometimes water pressure in a home begins to lessen or it may increase. If water flows properly from some taps, but not others, check the aerators ( screens ) on the affected taps. Aerators may be plugged with debris.* Similarly, the screens on laundry or dishwashers may be blocked.

(* Also see our Hot Water Heater Dip Tube page)

If water pressure is low all the time, on all taps, likely the Pressure Reducing Valve [PRV] needs adjusting. The PRV is typically a fist-sized, bell shaped valve with a bolt sticking out of the bell end. It’s typically near the household shut-off valve and water meter, and is part of the household plumbing, and is not owned by Howard County. The building code requires PRV’s on homes to protect household plumbing from high pressures that may occur in the municipal system.

Alternatively, if water seems to "spurt" on all taps, the PRV's screen may need to be cleaned. Spurting is when there is good pressure for a few seconds, and then the pressure lowers and flow slows down. The screen protects the PRV and household plumbing from debris. Sometimes you'll have to clean the screen, and adjust the PRV.

Here are some instructions on cleaning and adjusting your PRV. If you do not feel confident in doing this work, we recommend you contact a local plumber for assistance.

Diagram of typical PRV

Cleaning the Pressure Reducing Valve ( PRV ) Strainer Screen for Spurting

( Not all brands contain a cleanable straining device )

1. Turn water to the PRV off by turning off the main waterline leading to the PRV - this valve is usually located where the waterline enters the home. Leaving the water on during cleaning may cause flooding.
2. Ensure no one is using water during this procedure.
3. Have a bucket handy to catch the water in the household pipes, which drains back.
4. Unscrew the Strainer Plug which is a large cap screw on the upstream side.
5. Remove and clean the stainless steel Strainer Screen.
6. Reinstall Strainer Screen, and Strainer Plug.
7. Carefully turn water back on, and examine the system for leaks.

Adjusting the Pressure Reducing Valve ( PRV )

1. Unscrew the Lock Nut.
2. Adjust Pressure
3. For more pressure, turn the adjusting screw down ( clockwise ); or
4. For less pressure, turn the adjusting screw up ( counter clockwise ).
5. Retighten the Lock Nut so the adjusting screen cannot turn on its own.

Details of How the Pressure Reducing Valve (PRV) Works:

If you are interested in how PRV's work, here are more details, assuming the system starts with high pressure downstream in the home:

1. High downstream pressure pushes the rubber Diaphragm up, pulling up the Yoke and Disc which are connected.
2. The Disc moves closer to the Seat pinching off the water from the high pressure upstream supply from your water source.
3. The pinching creates friction, which reduces the downstream pressure.
4. The reduced downstream pressure allows the Diaphragm, Yoke and Disc to move down.
5. This reduces the friction lost through the seat, increasing the downstream pressure.
6. A balance is soon struck between processes 1 to 3, and 4 to 5, thus providing the appropriate pressure.
7. Adjusting Screw down increases the downward force on the Diaphragm, Yoke and Disc. This makes it harder to squeeze off the water flow, thus lessening the friction. The lesser friction increases the downstream pressure.
8. Adjusting Screw up decreases the downward force on the diaphragm, yoke and disc. This makes it easier to squeeze off the flow, thus increasing friction and decreasing the downstream pressure.