Checking your water pressure with a gauge: what the number tells you

If the water feels weak, or so strong that the taps spit, a pressure reading turns a vague complaint into a number. A simple gauge that screws onto a tap gives a rough idea in a few minutes. It will not diagnose the problem on its own, but it helps you decide whether to talk to a plumber, the water company, or neither. If you are dealing with weak water, read our low water pressure guide alongside this one.

Pressure and flow are different

Pressure is how hard the water pushes. Flow is how much water comes out over time. A gauge measures pressure. A home can have good pressure and poor flow, for example because of a narrow or partly blocked pipe, a partly closed valve, or a long shared supply. A simple flow check, timing how long it takes to fill a bucket of known size, is described in the low pressure guide. Plumbers often measure both.

What you need

A water pressure test gauge with a threaded connector. These are sold to fit a standard outside tap with a hose thread, or the threaded outlet of a washing machine valve. Check that the gauge's connector matches your tap, and that the gauge's range is sensible for household water. Cheap gauges are fine for a rough reading.

Where to take the reading

Use a tap that is fed directly from the mains:

• An outside tap, if it is on the mains. Most are.
• The washing machine cold valve, with the machine's hose removed. Turn the valve off first and have a towel ready.
• The kitchen cold tap is usually on the mains, but most kitchen taps have no thread to attach a gauge.

A tap fed from a loft cistern will show only the low pressure from the cistern's height, which tells you nothing about the mains. See low water pressure for how to tell which system you have.

Taking a reading

1. Turn the tap or valve off and screw the gauge on hand-tight.
2. Make sure nothing else is using water in the house: no taps, toilets filling, washing machine or dishwasher.
3. Open the tap fully. The gauge now shows the static pressure: the pressure with no water flowing.
4. Open another cold tap elsewhere in the house, such as the kitchen tap. The gauge reading will fall. This gives a rough idea of the running pressure, the pressure while water is being used.
5. Turn the tap off before removing the gauge.

Write down the time of day as well as the readings. Repeat at different times, such as early morning, mid-afternoon and late evening, over a few days.

What the number tells you

• A rough picture of your incoming supply at that point, at that time.
• Whether it changes with the time of day. A good reading at night and a poor one at breakfast suggests demand on the local network or a shared supply.
• How much it drops when another tap runs. A big fall can point to a restriction: a valve not fully open, a narrow or old supply pipe, a shared supply or a leak.

What it does not tell you

• The pressure upstairs. Pressure falls as water rises, so a shower upstairs gets less than a tap at ground level.
• The flow rate. You need the bucket test, or a plumber's flow meter.
• What is wrong. A low reading could be the network, your supply pipe, a stopcock, or a leak.
• An exact figure. A cheap gauge is a guide, not a calibrated instrument.

Water company or plumbing?

In England and Wales, CCW's low water pressure page explains where the water company's responsibility ends. It says Ofwat has set that companies should maintain a minimum pressure of seven metres static head (0.7 bar) in the communication pipe, which runs from the water main and ends at the outside stop valve, and that the company has no obligation to meet pressure requirements in your private supply pipe or inside the property. It also notes there is no regulated upper limit. These are the water consumer body's figures for the company's pipe, not a measurement your outside tap must meet.

If your readings are low:

1. Check your own side first. Make sure the internal stopcock is fully open and look for leaks. See stopcocks and water meters.
2. Check for local problems. Look on your water company's website for bursts or works in your area.
3. Keep a record. CCW recommends recording when low (or high) pressure happens over a period, for example two weeks, and reporting it to your water company. It says the company can visit to test the pressure at your property.

In Scotland, contact Scottish Water. In Northern Ireland, contact NI Water.

If your readings are high and you have banging pipes or spitting taps, read our pressure reducing valves guide and ask a plumber whether a PRV would help.

Can I test water pressure without a gauge?

You can get a sense of flow by timing how long a tap takes to fill a bucket, and CCW suggests some everyday signs, such as a bath or toilet cistern that takes a long time to fill. For an actual pressure figure you need a gauge, or ask your water company or a plumber.

Why is my water pressure lower in the morning?

Demand on the local network peaks when people get up and come home. A shared supply pipe makes this worse. If the drop is large and regular, record it and tell your water company.

Will the water company test my pressure?

CCW says your water company can visit to test the pressure at your property. Contact it with your readings and the times you took them.