12 Reasons for Low Water Pressure in Your House

Determining the cause of low water pressure in your home requires investigation. Signs of low water pressure include less water coming out of faucets and showerheads or an appliance, such as a dishwasher, taking longer to fill. The most common reason for low water pressure is a clogged sink aerator. However, clogged or corroded pipes, closed valves, leaks, pressure regulator problems, and issues with the water company can also be part of the problem.

A change in pressure can also happen suddenly and without warning. Keep reading to discover the reasons for low water pressure in your home and how to resolve the situation.

Identifying Low Water Pressure Problems

Confirm whether your water pressure is low with a test gauge. This simple device can attach directly to the hose spigot outside the home. After screwing the test gauge onto the spigot, turn the valve on and check the reading. Most homes operate between 30 and 80 psi. Attach the indicator to the laundry sink inside (if it has a screw-type water spout) and repeat the process to check if the water pressure problem is also inside the house.

Causes of Low Water Pressure in Your House
Clogged Water Pipes

If the water lines are clogged with limescale buildup, they can restrict the water flow, leading to low water pressure. Limescale and other mineral buildup can be more significant in areas with hard water.

How to fix it: This issue isn't easily resolved due to the widespread network of pipes running through the home. Contact a plumber to inspect and possibly replace the water lines. Also, consider investing in a water softener to help prevent this issue.

Corroded Pipes
Generally, galvanized steel lines start to corrode after about 20 years. Copper pipes last over 50 years, while brass pipes are fine for about 40 to 70 years.

How to fix it: If the pipes in the home are approaching the end of their life, then it may be time to replace the water lines before they start to leak. This requires a plumber's expertise.

Failing Pressure Regulator
While high water pressure can seem great, it can damage faucets, showerheads, appliances, and water lines if it's too strong. Because of this, homes in areas with high water pressure typically have a pressure regulator installed immediately after the main shut-off valve. If the pressure regulator is not set correctly, it could restrict the water flow more than necessary.

How to fix it: Adjust the pressure setting or hire a plumber. However, if the pressure regulator is set to 50 psi, and the water pressure throughout the home is lower than this setting, it could indicate that the pressure regulator is failing. A plumber may need to replace the regulator.

Leaking Water Pipes
If your water lines are leaky, there may be more than one leak affecting the home's water pressure. The bigger problem is that water leaks in the house can cause water damage, mold growth, and rot.

How to fix it: If you suspect leaking pipes are causing low water pressure, take immediate action. Inspect any visible water lines to locate the source of the leak. If you cannot find the leak, contact a plumber to resolve the issue.

Using Too Many Water-Using Appliances at Once
It's common to have more than one water-using appliance or fixture running simultaneously. This may be any combination of washing dishes, washing clothes, showering, watering the lawn, using sinks, filling tubs, or even pressure washing the patio or deck. The more appliances that use water simultaneously, the more the home's available water is tapped.

How to fix it: One or two faucets running simultaneously shouldn't affect the water pressure. The easiest way to resolve this issue is to stagger the household's water needs throughout the day.

Main Valve Is Partially Closed

The main water shut-off valve controls the flow of water into the home. If the valve is partially closed, the water pressure is reduced, which can cause water pressure issues affecting the whole house. The valve is usually located on the main water line immediately after the water line enters the home.

How to fix it: Find the valve. Depending on the type of valve, you may see a ball valve with a lever that moves 90 degrees or a gate valve with a handle that rotates to open and close the valve. Push the handle to align with the water pipe to open a ball valve. To fully open a gate valve, turn it counterclockwise until it no longer turns, then turn it back a quarter turn to avoid potential leaks or seizing.

Individual Valves Are Partially Closed
Water pressure problems can also be caused by partially closed individual valves, such as the valves on showers and sinks. This can occur when the water is turned off for a brief amount of time but not turned back on all the way, which prevents the water from the main valve from flowing freely through the individual valves.

How to fix it: Check underneath your sink to ensure the sink valve is open or closed, and do the same for the shower valves behind the cartridge. You'll need to remove the cartridge to access the valves.

Water Meter Valve Isn't Fully Open

The main valve isn't the only valve that can affect the water pressure for the entire home. Many houses have a water meter located right after the main valve. The local utility uses this to measure the home's water use.

How to fix it: Generally, a water meter isolation valve is installed after the water meter. If the water meter valve is partially closed, the flow of water into the home will be restricted. Find the valve, check it, and open it if it has been closed—fully or partially.

Faulty Plumbing Fixtures
If low water pressure affects one or two fixtures, such as a showerhead and sink, it's likely an isolated cause, such as a clogged aerator or cartridge. A faucet aerator reduces the volume of water without changing the pressure.

Dirt, rust, and limestone can build up inside the aerator, causing the fixture to restrict the water flow. A clogged cartridge found underneath the sink handle that stops and starts the water flow could also be at fault.

How to fix it: If you’re experiencing low water pressure in your shower, it’s likely due to limescale buildup. This can usually be fixed by cleaning your showerhead, as the holes in a showerhead can get clogged with debris.

Water Supply Issues
Sometimes, the water supplier or your water well may have problems. If you get your water from a municipal source, there could be a water main break, burst pipe, or pipework being done on the system. If you get water from a well system, the pump might malfunction, or the well might be running dry.

How to fix it: If your home is connected to the municipal water system, contact the local water supplier to determine if there is a water disruption.

If you're on a well system, check if the water pump has a mechanical problem, like a faulty motor or a tripped breaker. Adjust your pressure switch to try to unclog water lines, or install a water softener and water pressure regulator to help. If unsuccessful, contact a plumber specializing in well systems to assess the situation.

Shared Water Lines
Some homes may share one line of water from the municipal water supply. While shared lines are rare, your neighbor's clothes washer, dishwasher, or water heater and your water activities could affect the water pressure. When available water is divided among multiple households, it results in low water pressure.

How to fix it: While you can plan your water usage around your neighbor's schedule, the other option is to have a plumber replace the water lines from the municipal service to the home. This ensures the new line runs only to your home. A pipe replacement fix is costly but it is a more permanent solution.

Branch Lines Are Too Small
Some homes have normal water pressure running into the house that is restricted by narrow branch lines. These are the pipes that come off the main water line after entering the home. This supply line is what gets distributed to appliances and plumbing fixtures.

How to fix it: If you suspect that a narrow branch line is the cause of low water pressure issues, contact a plumber to assess the plumbing system. They will be able to determine if the branch lines are too small for the current network of appliances and plumbing fixtures. If the lines are too small, the plumber will likely suggest upgrading the pipes to a larger size to fix this issue.

When to Call a Professional
Most plumbing issues require an expert's assistance, and most DIYers with limited experience should not try to make significant plumbing fixes. You can check valves to ensure they're fully open, and if you have a pressure regulator, you can adjust the setting.

If you experience a sudden drop in water pressure, you should check with your water company to confirm whether it's your home or the water supply. If you have a home well, check the water pump is functioning correctly. Also, quickly inspect the house to see if you notice any leaks. If you can't discover the source of the problem, contact a plumber for guidance or a house call.