Why has my water bill suddenly gone up so much?

A metered water bill jumps for one of four reasons: a genuine change in usage, a leak on your side of the meter, an estimated reading being corrected, or a tariff or charge change. The order to check them in matters, because a leak is both the most expensive and the one with a remedy attached.

What you'll need

• Access to your water meter
• The bill and the previous one

Step by step

1. Check whether the reading is actual or estimated.The bill says. A jump caused by an estimate being corrected is not a jump in usage at all — it is a correction, and the pattern over a year is what matters.
2. Read the meter yourself now.Compare it with the closing reading on the bill. If the meter is well below, the bill is overstated and you have a straightforward billing correction to request.
3. Run the overnight leak test.Turn off every tap and appliance that uses water, read the meter, and read it again two hours later or first thing after leaving it overnight. Any movement means water is going somewhere.
4. Check the obvious internal culprits first.A leaking loo is the classic. Put a few drops of food colouring in the cistern, wait half an hour without flushing, and look in the pan. Colour in the pan means the flush valve is passing.
5. Check outside taps, troughs and irrigation.An outside tap left dripping, or an automatic irrigation system that was reset, can account for an enormous volume without anyone noticing.
6. Work out which side of the meter the leak is on.The company is responsible for its side; you are generally responsible for the supply pipe from the meter to the house. Ask them to check theirs — most will investigate free.
7. Ask about the leak allowance before repairing.Most companies operate a scheme that adjusts the bill where a leak has been repaired promptly, usually once per property. Ask what their scheme requires — some need the repair evidenced or done within a period.
8. Get the repair done and keep the invoice.The plumber's invoice with the date and the description of the fault is what the allowance claim is assessed on.
9. Check whether a change of tariff or occupancy explains it.A move from unmetered to metered, an assessed charge changing, or a household growing all change the bill legitimately.
10. Escalate to the Consumer Council for Water if unresolved.CCW is the free independent body for water complaints in England and Wales. Use the company's own complaints process first.

Tips

• Read your water meter on the first of every month and note it. Six readings turn any future dispute into a five-minute conversation.
• A slow toilet leak can waste more water than the rest of the household combined and makes no noise at all — check it first, every time.
• Ask about the leak allowance before you commission the repair, so you know what evidence they need.

Common mistakes

• Repairing the leak and then asking about the allowance — Some schemes have conditions about timing or evidence, and a repair with no invoice or date can be much harder to claim against.
• Assuming a high bill must be a leak — A corrected estimate, a new occupant, a change from unmetered charging or a filled paddling pool all produce the same shape of jump. Test before concluding.

If it doesn't work

Questions people ask