A higher than expected bill from your water supply company is sometimes a good indication of a leak, however, there could be a number of other reasons too.

This article covers:

• Reasons why your water bill could be higher than usual
• Who’s responsible for fixing a leak in your mains supply
• What to do if you can’t find your mains water external stop valve
• How to test for a leak on your exterior water supply pipe
• Pinpointing the exact location of a leak in buried pipework (without digging!)
• Exposing a leak, repairing it and submitting an insurance claim

Why do I have a high water bill?

There are many reasons why your water bill could appear higher than you expect. If you have a water meter, ask yourself the following questions. This could save the effort of arranging for someone to come and investigate a potential leak.

Check the information on your water bill

Do the dates cover the same period as your previous water bills?
It’s possible your water supply company has increased the period of time your bill covers compared with previous ones. Subsequently, this would increase the amount of water used for the billing cycle.

Has your high water bill previously been calculated using estimated readings?
Water use that was previously under-estimated would produce a change from the previous bill. The difference between the estimated reading and the current reading would make your bill higher than expected.

What has changed to impact the amount of water being used?

Has any maintenance work been done recently?
Decorating, building and gardening can all significantly increase the amount of water used in the household.

Is there any indication that taps or appliances are faulty?
Something as simple as a dripping tap can increase water bills. Leaking dishwashers or washing machines will also waste water.

Has the number of people using water in the property increased?
People who are less economical with their use of water could be the reason for a larger bill.

If you don’t have a meter, your bills are based on your water supply company’s assessment of the property. This is usually based on the number of bedrooms in the property. In theory this relates to the number of people using water. You can check with your water company their assessed charge is correct. For example, the water being used in a large house could be overestimated if only one person is living there.

You can ask your water supply company to fit a meter, and there shouldn’t be a charge to have it fitted. It’s not always possible to have this done immediately, so it may take some time before fitting it can be scheduled.

If there’s no obvious reason why your water bill is higher than usual it, leak investigation should be the next step.

Will my water company find and fix a mains supply leak?

Properties supplied with water must have an external stop valve. This valve controls the supply of water to that property. When a property contains more than one building, there is usually a single stop valve or multiple external stop valves to control the water. However, each building will have its own meter.

Water companies usually install a meter on the stop valve. When they’re inside communal blocks, they’re located away from the stop valve. Only the water passing through the meter is billable to the customer.

Please note:

The external stop valve is not the same as an internal stopcock (also called a stop tap). An external stop valve will be outside the property, usually under the pavement or the front garden. A stopcock controls the water supply inside a property. A stopcock is usually located beneath a kitchen sink.

What should I do if I can’t find my external stop valve?

If you can’t find your external stop valve contact your water supply company. They’ll be able to tell you where it is. If you can’t find it you should ask your water supply company to send someone. They’ll show you where it is.

If you don’t have an external stop valve, your water supply company would have to arrange for one to be installed.

Locating a leak on mains supply pipework

If you think there is a leak on a main water supply pipe, there’s a simple test to confirm whether it’s inside or outside of the property.

First, turn off the stopcock inside your property. Make sure it’s completely off by turning on a sink tap to drain the system. Water should stop coming out from the tap if the stopcock has been fully turned off.

Second, go to your water meter and make a note of the reading. If the reading increases, it indicates a leak on the mains supply pipework into the property. This means that water is passing the meter but is not going past the internal stopcock.

If it’s a small leak it might take some time for the reading to increase. Keep your stopcock turned off and take a reading after a few hours, or as long as possible.

No water meter?

If you don’t have a meter on your external stop valve you might need some professional help. A pressure test on the pipe between the external stop valve and internal stopcock will show whether a leak is present. Both the external stop valve and the internal stopcock are turned off so water is held between them. If there’s a leak the water pressure will drop.

If the test fails to show a leak is present on the main water supply pipework, the next step is to investigate a leak on pipework within the property.