Water meter leak test: find a leak yourself and work out how many litres you lose per hour
You suspect a leak at home, but you can't see any water or stain? A water meter leak test is the quickest check you can do yourself before calling anyone. You close every tap, take two readings 10 to 30 minutes apart, and find out whether water is entering your home while you aren't using it.
This guide covers two tools: the Water Meter Test page, with a timer and a calculator that turns the difference between two readings into litres per hour and per day, and the Smart Water Meter Code Decoder, for anyone who sees an alert on their meter or in their water company's app and doesn't know what it means. You will also learn the limits of the test in homes with a tank and a pump, which is the standard setup in Saudi villas.
What is a water meter leak test and what does it give you?
The idea is simple: the meter records every litre that comes in from the mains. If you stop all use and the meter keeps moving, the water is going somewhere you can't see.
- The Water Meter Test page puts the steps in order and gives you a 10, 30 or 60-minute timer. When you enter the two readings, it calculates the leak rate in litres per hour and the daily equivalent, and gives you a colour-coded verdict.
- The Smart Water Meter Code Decoder explains the general meaning of five common types of alert icon on smart meters: continuous leak, tamper, reverse flow, battery or signal, and high consumption. It tells you what to do in each case.
Both tools work anywhere in the world: litres and cubic metres are the same on every meter.
Who is this test for?
- Anyone who has received a high water bill and wants to know whether a leak is the cause before disputing it or booking an inspection.
- Homeowners who hear the tank filling at night, or see damp they can't explain.
- Anyone whose smart meter or water company app shows a “leak” or “high consumption” alert.
- Anyone who has had a leak repaired and wants to be sure it has really stopped.
When should you run it?
At a time when you can stop all water use for at least half an hour: late at night, after everyone has gone out, or on a weekend morning before anyone wakes up (in Saudi Arabia the weekend is Friday and Saturday). Don't start while the tank is refilling after heavy use, such as after laundry or several showers. Wait until the float valve stops.
Where do you run it?
At the water meter, which is usually in a box on the pavement, at the entrance of the house or next to the boundary wall. Open the page on your phone while you stand there. If the meter is far from the tank, you may need a second person to confirm that filling has stopped at the roof or ground tank.
What do you need before you start?
- Access to the meter and the ability to read all its digits, including the red digits or small dials. Wipe the glass if it is dusty.
- A full tank and a float valve that has stopped.
- All consumption switched off: taps, washing machines, water heaters that refill, automatic irrigation, evaporative (desert) coolers, and any reverse-osmosis filter that drains water.
- A phone for the timer and to photograph both readings. Photos prevent copying mistakes.
- 30 minutes with no use at all, or two hours if you want to add the tank level test.
Tools and how to use them, step by step
Water Meter Test
An interactive page with five numbered steps: make sure the tank is full, close all taps, record the first reading, wait at least 10 minutes (30 is better), then record the second reading.
Below it is a calculator with a “First reading (m³)” field that takes three decimal places, a “Test duration” list (10 minutes, 30 minutes or 1 hour; the default is 30), and a countdown timer with “▶ Start timer” and “Reset” buttons, then a “Second reading (m³)” field.
The calculation: leak rate (litres/hour) = (second reading − first reading) × 1000 × 60 ÷ test duration in minutes, then multiplied by 24 to estimate the daily waste. If you start the timer, the actual time from starting the timer to its end is used (or until you enter the reading, if you enter it earlier); otherwise the chosen duration is used. The result states which duration it was calculated on, and it recalculates instantly if you change the list. The page also explains the tank level test, which finds what the meter can't see.
Steps for correct use
- Prepare the house
Wait until the tank is full and you can't hear water flowing into it. Then close every tap, switch off the washing machine, water heaters and automatic irrigation, and make sure nobody will use water.
- Record the first reading accurately
In “First reading (m³)” type the black digits, which are whole cubic metres, then the red digits or dials, which are fractions of a cubic metre, for example 1234.567. Photograph the meter too.
- Choose the duration and start the timer
In “Test duration” choose the time you will actually wait; 30 minutes is a good choice. Tap “▶ Start timer”. At zero, a message tells you the time is up and to record the second reading, and the phone vibrates if it supports it.
- Record the second reading
Type the figure into “Second reading (m³)” and the result appears at once, with no button. If you started the timer, the rate is calculated on the actual time that passed, and the result says it was calculated on that many actual minutes. If you didn't, it uses the chosen duration.
- If the meter is still but the bill is high, test the tank
Close the valve that feeds the tank, mark the water level and don't use any water for two hours. A drop in level means a leak in the tank or in the pipes it feeds.
How to read the result
- Green, the meter barely moved: under 0.5 litres per hour. No visible leak before the tank. If the bill is still high, run the tank level test.
- Yellow, a possible small leak: from 0.5 to under 10 litres per hour, with the daily quantity shown. Look for a leaking toilet cistern or a float valve that doesn't close fully, and repeat the test for an hour to be sure.
- Red, a clear leak with an urgent inspection recommended: 10 litres per hour or more, which is at least 240 litres a day. Book an inspection to locate it before the bill and the damage grow.
- “The second reading is lower than the first”: the figures were entered incorrectly, so read them again.
Smart Water Meter Code Decoder
An unofficial, independent interactive guide from Kashf. It is not affiliated with the National Water Company or any other water utility, and the reference for the meaning of any symbol is the operator of your meter. You choose one of five common icons, and a card appears with the alert's name, its general meaning and suggested actions:
- Continuous leak (red): flow without a break for several hours in a row.
- Tamper or removal (yellow): an attempt to remove or interfere with the meter. It can appear by mistake after a knock or nearby maintenance, and has nothing to do with a leak inside the home.
- Reverse flow (yellow): water flowing back from the home towards the network, usually because of pressure fluctuations in the network.
- Low battery or no signal (yellow): unrelated to leaks; fixing it is the water company's responsibility.
- High consumption (red): consumption has exceeded your usual pattern.
The explanations are general and apply to most smart meters, in Saudi Arabia and elsewhere. They are not error codes for a specific model.
Steps for correct use
- Note exactly what you see
Look at the meter display or the notification in your water company's app, and note the shape of the icon and the alert text if there is any.
- Tap the closest icon
Under “Choose the alert icon you see”, tap one of the five. If none matches exactly, choose the closest category, as the page recommends.
- Follow the actions in order
Read the meaning, then the suggested actions. For the leak and high-consumption alerts, the first practical step is a meter test with every tap closed for 30 minutes.
- Confirm with the operator if needed
Tamper, battery and repeated reverse-flow alerts concern the meter itself. Contact the water company about them through its official channels, and don't open the meter cover yourself.
How to read the result
- Red (continuous leak or high consumption): worth checking today. Run a meter test. If the meter moves with no use, book an inspection to locate the leak.
- Yellow (tamper, reverse flow or battery): usually unrelated to your home's plumbing. Keep an eye on it, and report it to the water company if it repeats or persists.
Note: in a home with a tank, a smart meter may record long flow because the tank is refilling after heavy use, or because its float valve doesn't close properly. The second case is real waste that is worth fixing. That is why the leak-alert actions tell you to close the tank inlet valve, or wait until the float has completely stopped filling, before judging the meter's movement.
A worked example: what do 15 litres in half an hour mean?
You read the meter at 1234.567, and after 30 minutes with no use at all it shows 1234.582.
- The difference is 0.015 m³, which is 15 litres.
- The rate = 15 × 60 ÷ 30 = 30 litres per hour, a clear leak in the tool.
- Per day: 30 × 24 = 720 litres, and per month about 21.6 m³.
- If your usual consumption is 25 m³, these cubic metres raise the estimated bill by about SAR 97 a month under Saudi residential tiers, including wastewater and VAT.
Even the lower limit of red, 10 litres per hour, means 240 litres a day and about 7.2 m³ a month. To work out the cost in your case in more detail, with your own tariff if you live outside Saudi Arabia, read the leak waste guide.
The meter and the tank: what the test shows and what it misses
In most Saudi homes water travels like this: mains → meter → tank → booster pump → house. The meter only sees what goes into the tank.
- The test shows: a leak in the line between the meter and the tank, a tank float valve that doesn't close so water overflows, and a large tank leak that makes it refill during the test.
- It may miss: a leak after the pump, or a slow leak from the tank, because the float only opens after the level has dropped by a certain amount. That is why the tank level test comes in, for two hours after closing the inlet valve.
- In a home without a tank, such as some apartments connected directly to the mains, and in many homes outside Saudi Arabia, the test covers all the pipes after the meter.
If a leak shows up and you can't tell whether it is before or after the tank, that is exactly what an inspection with equipment determines. For leaks in the tank itself, read the water tank leak guide.
Common mistakes that spoil the result
- Starting while the tank is filling: the tool reads the filling as a leak. Wait for the float to stop.
- Forgetting an appliance that uses water: automatic irrigation, an evaporative cooler, a reverse-osmosis unit that drains, a water heater that refills, or a washing machine on a delayed cycle.
- Reading only the black digits: a small leak shows in the red digits or dials. Enter three decimal places.
- Not starting the timer, then waiting longer or shorter than the chosen time: without the timer the calculator divides by the chosen duration, so the rate is inflated or shrunk. The same happens if you take the second reading long after the timer ends.
- Someone using water during the test: a single toilet flush is several litres and spoils half an hour's result.
The honest limits of the tool
- The test tells you whether water is leaking before the tank. It doesn't tell you where.
- A still meter doesn't mean a leak-free home if there is a tank and pump; a leak after the tank needs the level test.
- The result is only as accurate as the reading. A meter that only shows whole numbers won't catch a small leak in 10 minutes.
- The decoder's explanations are general and unofficial. The meaning of a symbol on your meter is confirmed by the operator.
- If you doubt the accuracy of the meter itself, that is a matter for the water company, not a home test.
When do you need a leak detection technician?
- If the result is yellow or red and you can't find a toilet cistern or float valve that obviously explains it.
- If the meter is still but the tank level drops in the two-hour test.
- If the result comes with damp, the sound of water in a wall, or sinking tiles.
- If you need a technical inspection report to submit to the water company.
At Kashf, the technician locates the leak without demolition, using pressure testing, acoustic sensors, thermal cameras and a safe tracer gas for buried lines. You receive a written inspection report with a serial number and a verification code that you can check on the verification page. Book through the order page or on WhatsApp 0544027180. On-site service is available in Saudi Arabia only; the online test works anywhere.
Frequently asked questions
How do I do a water meter leak test myself?
Wait for the tank to fill, close every tap and appliance, and record the meter reading including the red digits. Wait 30 minutes without any use, then record a second reading. Any movement means water is coming in while you aren't using it. The Water Meter Test page calculates the rate in litres per hour and gives you a colour-coded verdict.
The meter is turning with all the taps closed. Is that definitely a leak?
Usually yes, as long as the tank is full, the float has stopped and no appliance that uses water is running. In that case the movement means a leak in the line between the meter and the tank, a float valve that doesn't close, or a large leak from the tank. Finding the location needs an inspection with detection equipment.
How long should a meter test take?
Ten minutes is enough to catch a large leak. Half an hour gives a clearer result for a medium leak. An hour is good if the result is yellow and you want to be sure. If you don't use the timer, choose the same duration you will actually wait, because the calculation divides by the chosen time.
How do I read a water meter, and what do the red digits mean?
The black digits are whole cubic metres. The red digits or small round dials are fractions of a cubic metre, usually down to the litre. Write the reading like 1234.567: the three digits after the decimal point are litres. Some meters have a small indicator that spins with any flow, and its movement alone shows that water is passing.
The meter is still but the bill is high. Why?
The leak may be after the tank, in the pipes fed by the pump, or a slow leak from the tank that isn't enough to open the float during the test. Close the tank inlet valve, mark the water level and don't use water for two hours. A drop in level means a leak that needs an inspection.
What does a leak alert on a smart water meter mean?
It usually means the meter has recorded continuous flow without a break for several hours, a pattern that is unusual in homes. In a home with a tank, though, it can be caused by long refilling or a float valve that doesn't close. Run a meter test to check, and ask your water company for the exact meaning on your meter.
Does a battery or tamper alert on the meter mean there is a leak?
No. A battery or lost-signal alert concerns the meter's transmitter. A tamper alert concerns an attempt to move or interfere with the meter, and it can appear after a knock or nearby maintenance. Both are the water company's responsibility, so don't open the meter yourself, and report it if the alert continues.
Does a water meter leak test show where the leak is?
No. A water meter leak test answers one question: is water coming in while you aren't using it? The location, whether in a buried line, a tank or under bathroom tiles, is found by an inspection with acoustic and thermal equipment, pressure testing and tracer gas, without random demolition.
After a repair, how do I make sure the leak has stopped?
Repeat the meter test the same way and for the same time, ideally half an hour or an hour. The result should be green, meaning under half a litre per hour. If your home has a tank, repeat the level test too. Then compare the next bill with the bills from before the leak.
Related services
On-site inspections are available in Saudi Arabia; the tools and guides work anywhere.
This guide is educational. It explains estimation tools that help you understand a situation and decide what to do next; confirming a leak and pinpointing it always requires an on-site inspection with instruments. Structural questions are for a licensed engineer to decide.