11 Reasons for Low Water Pressure in Your House (2024)

When there is a problem with low water pressure in your house, it's important to figure out why and how to fix it. The most common cause of low water pressure is clogged sink aerators, but pressure regulator problems, corroded pipes, closed valves, and issues with the water company can also be part of the problem.

Low water pressure can occur wherever there is plumbing and can affect anywhere from the kitchen sink to the shower heads throughout your house. A change in pressure can also occur suddenly and without warning. Keep reading to discover the reasons for low water pressure in your house and how to resolve the situation.

Identifying Low Water Pressure Problems

If you suspect a water pressure problem or simply want confirmation that the water pressure is low, you can check the water pressure with a test gauge.

A test gauge is a simple device that can attach directly to the hose spigot on the outside of the home. After screwing the test gauge onto the spigot, turn the valve on and check the reading. To check if water pressure problem is throughout the house, you can attach the gauge to the laundry sink and repeat the process.

Reasons for Low Water Pressure in Your House

Using Too Many Water-Using Appliances at Once

It's common to have more than one water-using appliance or fixture going at the same time. 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 are using water at the same time, the less water there will be for all applications.

Having one or two faucets running at the same time shouldn't be enough to affect the water pressure, butthe easiest way to resolve this issue is to stagger the water needs of the household throughout the day.

Main Valve Is Partially Closed

The main water shut-off valve is responsible for controlling the flow of water into the home. If the valve is partially closed, then it means that the water pressure is being reduced and can possibly be the cause of 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.

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. To open a ball valve, simply move the handle so that it lays in line with the water pipe. To fully open a gate valve, turn it counterclockwise until it can no longer turn, then turn it back a quarter turn to avoid potential leaks or a seized valve.

Individual Valves Are Partially Closed

Water pressure problems can also be caused by individual valves being partially closed 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. Check underneath your sink to make sure the sink valve is completely open or closed, and do the same for the shower valves, which are located 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. In many houses, there is a water meter located right after the main valve. This is used by the local utility to measure the water use for the home. Generally, there will be a water meter isolation valve installed after the water meter. If the water meter valve is partially closed, then the flow of water into the home will be restricted.

Failing Pressure Regulator

While high water pressure can seem like a good thing, if the water pressure is too high it can damage the faucets, showerheads, appliances, and water lines. With this in mind, homes located in areas with high water pressure will typically have a pressure regulator installed immediately after the main shut-off valve.

If the pressure regulator is not set correctly, then it could be restricting the flow of the water more than necessary. You can adjust this on your own or contact a plumber to adjust it for you. However, if the pressure regulator is set to about 50 psi, but the water pressure throughout the home is lower than this setting, then it could indicate that the pressure regulator is failing. Contact a plumber to replace the faulty regulator and restore normal water pressure to the home.

Faulty Plumbing Fixtures

If the low water pressure seems to only be affecting one or two fixtures such as showerheads and sinks, then there is likely an isolated cause for this situation.

Aerators on a sink faucet fixture are intended to reduce the volume of water without changing the pressure, but dirt, rust, and limestone can build up inside the aerator, causing the fixture to restrict the flow of water. A clogged cartridge, which is found underneath the sink handle and stops and starts the flow of water, could also be at fault. 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 shower head, as the holes in a showerhead can get clogged with debris.

Water Supply Issues

In some cases, low water pressure can be caused by the water supplier. If your home is connected to the municipal water system, then contact the local water supplier to determine the reason behind the low water pressure.

If you're on a well system, a problem with the water supply is a much more concerning issue and can mean the well pump may not be running. This can be caused by a mechanical problem, like a faulty motor or a tripped breaker, but it may also happen if the well runs dry. Contact a plumber who specializes in well systems to assess the situation and suggest the best course of action.

Corroded or Clogged Water Pipes

If the water lines are badly corroded or clogged with limescale buildup, then it can restrict the flow of water, leading to low water pressure problems.

Generally, galvanized steel lines will start to corrode after about 20 years. Copper pipes last for over 50 years, while brass pipes are fine for about 40 to 70 years. If the pipes in the home are approaching the end of their life, then it may be time to replace the water lines before the pipes start to leak.

Limescale and other mineral buildup can be a bigger issue in areas with hard water. Due to the widespread network of pipes running through the home, this isn't an issue that can be resolved easily. Contact a plumber to inspect and possibly replace the water lines. Also, consider investing in a water softener to help prevent this issue in the future.

Leaking Water Pipes

If you have a leak in the water lines, then there may be more than one leak, which can affect the water pressure for the home. The bigger problem is that water is leaking into the home, causing water damage, mold growth, and rot.

If you suspect that the cause of the low water pressure is leaking pipes, take immediate action. Inspect any visible water lines to track down the source of the leak. If you cannot locate the leak, contact a plumber to resolve the issue.

Shared Water Lines

While rare, in some circ*mstances, the water line running into the home is shared with one or more neighboring homes. So, if the neighbor takes a shower, washes their car, or puts a load of dishes on, then this will affect the water pressure in your home as the water supply is divided between multiple households.

While you can try to plan your water usage around your neighbor's schedule, the other option for fixing this problem is to have a plumber replace the water lines from the municipal service to the home. This will ensure that the new line runs only to your home, though pipe replacement can be a costly job.

Branch Lines Are Too Small

Some homes have normal water pressure running into the home, but the water pressure is restricted by narrow branch lines (pipes that come off the main water line after it enters the home) when the water is distributed to appliances and plumbing fixtures.

If you suspect that this is the cause of the 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, then the plumber will likely suggest upgrading the pipes to a larger size to fix this issue.