Why Has My Water Bill Suddenly Increased?

In short

An unexplained rise in your water bill may come from changed usage, an estimated or incorrect reading, or a hidden leak in toilets, taps, appliances, radiators or pipework. A simple meter test can help you check.

On this page

• Step-by-step meter test
• Common hidden leak clues
• Using the internal stop tap
• If you have an active leak
• Who is responsible for supply pipes?
• Frequently asked questions

Step-by-step meter test

If you are on a water meter and your bill has jumped unexpectedly, a simple meter test can help you determine whether there is a leak. This method is based on WaterSafe guidance:

1. Turn off all taps, appliances and anything that uses water — washing machines, dishwashers, showers, outside taps, irrigation systems.
2. Locate your water meter — usually outside your property under a small cover, or sometimes inside.
3. Note the meter reading — write down the exact numbers and, if your meter has one, the position of the dial or leak indicator.
4. Avoid using any water for at least 30–60 minutes (or longer if practical — overnight is ideal).
5. Check the meter again. If the reading has changed, water is being drawn somewhere — this strongly suggests a leak.
6. If the reading has not changed, the increase may be due to an estimated bill or a change in usage rather than a leak.

Do not interfere with or tamper with the meter itself or any sealed supplier equipment. You are only reading the display.

Common hidden leak clues

Leaks are not always visible. Here are the most common signs that water is escaping somewhere in your home:

• Constantly refilling toilet — a faulty fill valve or flapper can silently waste hundreds of litres per day.
• Damp or musty areas — patches on walls, ceilings, floors or skirting boards with no obvious source.
• Reduced water pressure — a sudden drop in flow at taps or showers can indicate a leak in the supply pipe.
• Running-water sounds — a hissing or trickling noise when nothing is turned on.
• Warm patches on the floor — can indicate a leak in a hot water or central heating pipe under the floor.
• Waterlogged garden or lush patches — unusually green or soggy areas in the garden can indicate an underground supply-pipe leak.
• Dripping overflow pipes — a toilet or tank overflow dripping outside means the fill valve is not shutting off properly.
• Unexplained mould or mildew — persistent mould in areas that should be dry can be a sign of hidden moisture.

Using the internal stop tap to narrow it down

Your internal stop tap (usually under the kitchen sink or near where the water enters the property) lets you isolate the water supply inside your home. If you turn it off and the meter stops moving, the leak is inside the property. If the meter keeps moving with the internal stop tap closed, the leak is likely between the meter and the stop tap — possibly in the underground supply pipe.

This information is very helpful when you call a plumber, as it narrows down where to look.

If you have an active leak right now

Who is responsible for supply-pipe leaks?

Responsibility for water supply pipes depends on where the leak is:

• The water company is typically responsible for the mains pipe up to the boundary of your property or the stop tap in the street.
• The homeowner is usually responsible for the supply pipe from the boundary into the property, and for all internal pipework.
• Some properties have shared supply pipes, which can complicate responsibility.

This is a general guide only — check with your water company for the specific rules in your area. Some water companies offer free or subsidised leak detection and repair for supply pipes, so it is always worth asking. Adrian does not make any legal guarantee about responsibility — always confirm with your supplier.

For internal plumbing leaks, Adrian provides general plumbing repairs and emergency call-outs across Grays and nearby areas. Request a callback to discuss the issue.

Disclaimer: This article provides general guidance only. Always follow your appliance manufacturer's instructions and use an appropriately qualified professional for gas, electrical and plumbing work. Gas work must be carried out by a Gas Safe registered engineer.