Bad Water Pressure in a House

A partly closed shutoff valve can result in poor water pressure.

When the water pressure in a house drops, the problem may lie practically anywhere within the system of lines and valves that connect the street's water main to the home's water meter box, and from there to the various rooms. This annoying problem can make it difficult to use more than one water faucet or appliance at a time, forcing homeowners to check for half-closed shutoff valves, pinched water lines or obstructions from rocks or other objects that find their way into the system.

Symptoms

Poor water pressure in a home causes many inconveniences, especially when the occupants try to use multiple water fixtures at the same time. A person taking a shower, for instance, may suddenly have not enough water to rinse away all the soap because someone in the kitchen turned on the water faucet. If neighbors do not experience similar issues, the pressure problem originates not with the street's water main but with the home's internal water system, according to Ask the Builder.

Valve Issues

In many cases, the problem with a home water pressure comes from a partly closed water shutoff valve. Some valves, notably gate valves or the common washer-and-stem variety, can appear fully open while actually maintaining a half-closed state due to a malfunction. In other cases, a builder or plumber may have simply reduced the flow from the valve without remembering to re-open it.

Blocked Lines

Water lines can suffer accidental crushing or flattening during construction, plumbing jobs or other maintenance work, squeezing the pipe until it no longer allows for adequate water flow. This type of incident can occur when a plumber installing the line refills the trench with dirt and accidentally knocks a heavy piece of rock or cement onto the line. Another type of obstruction involves rocks or other foreign objects blocking the flow of water inside the water line.

Meter Problems

In some cases, the water meter box may suffer an obstruction when a foreign object enters it from the water line, resulting in poor water pressure. If the line leading to the water meter exhibits strong water flow, the homeowner will have to have the faulty water meter replaced with a new unit by contacting the local water authority.

Troubleshooting

Homeowners troubleshooting a water pressure problem should start with the water shutoff valves, checking the status of every valve that serves the water line from the street to the home. The water meter has two shutoff valves, one on each side, with a metal bar positioned toward the meter's center point. If all water shutoff valves appear open, troubleshooters should suspect a line blockage. If the water appears to flow properly at the point where the water exits the water meter, the blockage must be further down that particular pipe. If all these steps fail to reveal the problem, homeowners should have a professional test the water meter itself.

References

• Ask the Builder: Solving Low Water Pressure Problems