If the hot water pressure is low, but the cold is fine: You may have sediment and limescale build-up in the pipes or faucet, or it could be caused by a partially closed or restricted shutoff valve.
If your cold water pressure is fine but your hot isn't, a partially closed valve is a likely cause. Your hot water heater has a shut off valve that can become partially closed.
If your cold water pressure seems fine but the pressure of your hot water is not, the shut off valve on your water heater might not be fully open. If that valve is partially closed, it will restrict the flow of hot water, leading to low pressure for the hot water only.
Open the water main up all the way so it is fully turned on. The pressure regulator is not configured correctly or needs to be replaced. Check the setting on the pressure regulator. If it is set correctly but you are having low water pressure issues in both hot and cold water supply lines, it needs to be replaced.
If the hot water pressure is lower than the cold and occurs throughout the whole house, you could have a problem with a plumbing system. If you have a single-handle faucet in your shower or tub, your mixing valve that controls the amount of hot and cold water sent to the showerhead may be stuck or worn out.
One of the most common causes of low hot water pressure is mineral and scale buildup in the pipes. This is due to hard water—the term for water with high levels of dissolved mineral content like calcium and magnesium.
Buildup throughout the water supply commonly causes low hot and cold water pressure. Sediment or mineral buildup happens in pipes or water tanks when hard water deposits minerals or sediments over time. Sediment and mineral deposits build up and damage plumbing lines by creating blockages or corroding metal.
Plumbing codes require that your home's water pressure be 80 pounds per square inch (psi) or less. Most experts recommend 50-60 psi. If your old water heater leaked prematurely, check your home's water pressure with a pressure gauge with a lazy hand (available at hardware stores and home centers for a few dollars).
Pressures can vary depending on your boiler, but the typical pressure expectation is between 1 and 2 bar.
Damage – Regular flushing helps prevent sediment from clogging/blocking your water heater's pressure and relief valve. The pressure and relief valve is very important because one of its duties is helping to prevent your water heater from exploding.
Tip: The build up of sediment in the tank can reduce your water heater's energy efficiency and also clog your water lines. Avoid these problems and increase the life of your unit by flushing your water heater every six months.
Every homeowner knows how important it is to clean and maintain your systems and appliances. However, many homeowners don't know that flushing a water heater every year can remove a build-up of sediment from the bottom of the tank.
The cause of your low hot water pressure could be debris and sediment in showerheads and taps, water leaks, blocked filters, a faulty tempering valve or something else.
The most common cause of low shower pressure is a blocked showerhead, as a result of limescale build-up. These blockages obstruct the water flow, leading to reduced pressure over time. Most showers are fitted with a filter, protecting the pipework from debris, but this can become partially blocked by scale.
Leaky, corroded and clogged pipes can lead to low water pressure in the shower. The showerhead might be so old it needs to be replaced. The shower controls could also be responsible for flow issues.
A gravity fed system will be located in two places. First, the cold water tank will be located in the roof, attic or loft. Second, the hot water cylinder will be located in an airing cupboard, which will usually be located near the bathroom.
Water pressure is measured in 'bar', and generally speaking, anything 0.3 bar or below requires a low water pressure tap or shower, and anything at 1.0 bar or above requires a high water pressure tap or shower.
For it to work as efficiently as possible, you need stable water pressure within the system. If your boiler isn't working properly and you're not getting hot water as normal, you'll often find the problem is your boiler pressure is too low, or sometimes too high.
Check Your Aerator
If you have especially hard water, aerators become clogged with hard water buildup, a common cause of low water pressure in kitchen fixtures. Clean your aerator for a quick and easy DIY fix. Remove the aerator from the faucet using pliers and a towel (to prevent scratching). Some twist off.
Clogged aerator screen
The aerator is the first to check when a faucet has low water pressure. Most faucets have aerators at the base or inserted inside the spout. Sediments, mineral deposits, or small debris can clog the aerator over time, which results in low water pressure.