How to check water leakage at home with your water meter

A water bill that keeps creeping up, an overhead tank that empties sooner than it used to, a damp patch spreading along the bathroom wall: each can point to a leak you cannot see. This guide explains how to check water leakage at home with the meter you already have, then how to narrow the leak down to a toilet, a tap or a pipe. You need a pen, a phone camera and a few drops of food colouring.

Start with the meter test

The US Environmental Protection Agency's WaterSense programme gives a simple test: check your water meter before and after a two-hour period when no water is being used. In an Indian home, a few extra steps give a result you can trust.

1. Pick a two-hour window when nobody will use water and the supply is on. If water comes only at set hours, test then; a dry main keeps the meter still even when there is a leak.
2. Close every tap. Make sure the washing machine, geyser and garden hose are not drawing water. An RO purifier keeps taking water while it refills, so switch it off at the socket.
3. If the meter feeds a sump or an overhead tank, let the tank fill completely and check that the float valve has shut. Otherwise the meter will simply record the tank filling.
4. Note the full reading, including the red digits or small dials, or take a clear photo of the meter face.
5. Wait two hours without using any water.
6. Read the meter again. Any movement means water is leaving somewhere after the meter.

If the meter moved, look at the pipes between the meter and the tank, at the tank itself, and at any fixture fed straight from the supply. A thin stream from the overflow pipe on the terrace usually means the float valve is not closing.

If the meter did not move, the leak may sit after the tank, where the meter cannot see it. Close the tank's inlet, mark the water level inside with tape or a marker, use no water for two hours, and check whether the level has dropped.

Reading the dial on a domestic meter

Most domestic water meters show volume in cubic metres, and one cubic metre is 1,000 litres. The black digits count whole cubic metres, so when the last black digit moves up by one, 1,000 litres have passed. The red digits, or a row of small pointer dials, show the fraction of a cubic metre.

Pointer dials are usually marked with a multiplier. On a dial marked ×0.1, each number is 100 litres. On ×0.01 it is 10 litres, and on ×0.001 it is one litre.

Many meters also have a small star, triangle or toothed wheel on the face that turns with even a slow flow. If it is turning while every tap is closed and the tank is full, you have your answer without waiting two hours.

A meter that can be read remotely sends its readings at regular intervals, so a reading that keeps climbing while the house is empty shows up in the record without anyone visiting the meter. Terms such as AMR and the meter register are explained in the glossary.

Toilets, taps and showers

A toilet cistern can trickle into the pan all day without a sound, which makes it a frequent hidden leak. The dye test takes ten minutes.

1. Lift the cistern lid. For a concealed cistern, use the access panel behind the flush plate.
2. Add a few drops of food colouring to the water in the cistern. Do not flush.
3. Wait ten minutes.
4. Look in the pan. WaterSense puts it plainly: if any colour shows up in the bowl after 10 minutes, you have a leak.

The usual causes are a worn rubber seal at the bottom of the cistern, or a fill valve set so high that water spills into the overflow tube. Both are cheap parts.

Dripping taps are easy to ignore. WaterSense figures show what they cost. A tap that drips once a second can waste more than 3,000 gallons a year, which is about 11,000 litres, or roughly 30 litres a day. A showerhead leaking ten drips a minute wastes more than 500 gallons a year, about 1,900 litres.

WaterSense also estimates that leaks in the average household can waste more than 9,300 gallons, about 35,000 litres, every year. That is an American average and Indian homes use water differently, so treat it as a sense of scale, not an estimate for your flat.

In Indian bathrooms, look closely at the health faucet and the angle valve that feeds it, the joint under the wash basin, and the inlet hose behind the washing machine. Older screw-down taps drip when the washer wears out; quarter-turn taps drip when the ceramic cartridge wears.

What to fix first

1. Anything that runs all the time. An overflowing tank or a toilet that never stops filling wastes water around the clock, and the fix is usually a float valve or a cistern seal.
2. Leaks inside walls, floors and ceilings. Damp patches, peeling paint and mould mean water is soaking into the structure. These cost more the longer they wait.
3. Dripping taps and showers. A new washer or cartridge is cheap, and the saving starts the same day.
4. Slow seeps at joints. Tighten or reseal fittings under sinks and behind appliances, then check them again a few days later.

After any repair, run the two-hour meter test again. A meter that stays still is the proof that the job is done.

When to call a plumber or the society

• The meter moves but you can find nothing. The leak is probably in a buried or concealed pipe. A plumber can isolate sections of the line and pressure-test them to find the faulty run before any wall or floor is broken open.
• Damp appears on a shared wall or the ceiling below. In a flat, tell the society office. The leak may be in a neighbour's line or a common riser, and the repair may fall to the society.
• Water is escaping before the meter. The pipe on the street side of the meter is usually the responsibility of the water supplier or the society, not the household. Report it rather than opening it yourself.

Society managers can use the same method at building scale. Where every flat has its own meter, residents can run the two-hour test on the same night, and a flat whose meter moves with no water in use stands out at once. Comparing the society's main meter with the total of the flat meters shows how much is lost in common pipes and tanks. Our other articles explain how utilities make the same comparison across a town.