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How to find a water leak at home

A silent leak can cost more than all your family's showers. You can find most leaks yourself with your water meter, a few drops of food colouring and a cup. Here is how.

Do the meter leak test

1. Make sure nobody uses water: no taps, flushing, washing machine, dishwasher, irrigation or pool top-up.
2. Read the meter, including the red digits or dials, and note the time.
3. Read it again after an hour or more. Overnight is best.
4. If the reading has changed, or the small leak wheel turns, water is leaking somewhere.

If your house has its own stopcock where the pipe enters, close it and test again. If the meter still moves with the house shut off, the leak is between the meter and the house, often underground.

Check the toilets first

Toilets are the most common household leak, and often a silent one. Do the dye test:

1. Take the lid off the cistern.
2. Add a few drops of food colouring.
3. Do not flush for 15 to 30 minutes.
4. If colour appears in the bowl, the cistern is leaking past the flapper or seal.

Other signs are water running into the overflow pipe, a trickle that you can hear long after flushing, and water on the floor round the base.

A worn flapper or seal is a cheap part from a hardware store. Many people can replace one: close the toilet's stop tap, flush to empty the cistern, and swap the part. If the leak is at the base or in the pipes, call a plumber.

What a small leak costs

In the book's example, a meter moves by 80 litres in 8 hours overnight, with no water used. That is 10 litres an hour, 240 litres a day and 7.2 kilolitres a month. At an example price of R30 a kilolitre, the leak costs R216 a month. The cause was a toilet flapper that cost R60 to replace.

Measure a dripping tap

Put a cup under the drip and time it. A 250 ml cup filled in 10 minutes is 1.5 litres an hour, or 36 litres a day. Worn washers and cartridges are cheap to replace. Close the tap's stop valve or the main stopcock first.

Other places to look

• outside taps and hosepipe connections;
• the irrigation system;
• the geyser overflow pipe;
• washing machine and dishwasher hoses;
• the pool;
• wet or unusually green patches in the garden, which can show an underground leak.

Who must fix it

A leak on your side of the meter is the owner's to fix. A leak in the street, at the meter or in the mains is the municipality's: report it with a photo and keep the reference number. If you rent, report the leak to your landlord in writing.

Keep the plumber's written proof of a repaired leak. You may need it if you query a high bill.

This article is based on Chapter 7 of Cutting Your Electricity and Water Bills.