Warehouse water bill gone up? How to check for a hidden leak
A bill that jumps while the site is doing the same work as last quarter usually has one of three explanations: a leak on the supply pipe under the yard, a leak inside the building, or several small faults adding up. Half an hour with the meter tells you which.
Before you start: find the meter and the stopcock
On most industrial estates the water meter sits in a chamber near the site entrance, in the verge or under a small cover in the car park. The internal stopcock is wherever the main comes into the building, often in the plant room, the welfare block or a cupboard near the loading bay. If nobody on site knows where either one is, find out now. It is the first thing the engineer will ask, and it is much easier to answer on a quiet Tuesday than in the middle of a leak.
Larger sites may have a main meter and sub-meters for a wash bay, an office block or a second unit. Each one can be read the same way.
Step 1: read the meter when the site is shut
Pick a time when nothing should be using water: overnight, or a Sunday if the site closes. Read the meter, including the red dials or the last digits, and read it again thirty minutes later. Many meters have a small spinning disc or star that turns with any flow; if it is turning when the site is empty, water is moving somewhere.
If the site has a smart or automatically read meter, ask the water retailer for the half-hourly data. A line that never drops to zero at night tells you the same thing as a spinning dial.
Step 2: close the stopcock and read it again
Close the internal stopcock fully and watch the meter for ten minutes.
| Stopcock closed | What it means | Where to look next |
|---|---|---|
| Meter stops | The loss is inside the building, between the stopcock and the taps, cisterns, plant and machinery. | Step 3: the usual culprits, area by area. |
| Meter keeps turning | The loss is on the supply pipe between the meter and the stopcock, usually under the yard or car park. | Step 4: the supply pipe. This needs acoustic or tracer-gas equipment to find. |
| Meter slows but does not stop | Both, or a stopcock that no longer closes fully. | Have the stopcock checked, then repeat. |
Step 3: the usual culprits inside the building
Small faults cause more rising bills than burst pipes do, and they hide in plain sight because each one looks harmless on its own.
- Toilets and urinals. Lift the lid on the cisterns in the welfare block; water trickling into the overflow or down the back of the pan is a fault. Older cistern-fed urinals flush all day unless the control is working.
- Taps and showers. One drip a second is roughly 15 litres a day, and a busy welfare block can have several.
- Plant. A pressurisation unit topping up the heating every day, a safety valve dripping into its tundish (the small open funnel below it), a booster pump that runs when nothing is open.
- Feeds to machinery and wash-down points. Hoses left running, a solenoid valve that no longer shuts, a feed with a slow leak where it drops down a column.
- Outside taps and wash bays. A tap in the yard somebody forgot, a vehicle wash with a valve that passes.
Isolate each suspect in turn and watch the meter. When it slows, you have found one of them; when it stops, you have found the last.
Step 4: if the meter turns with the stopcock closed
The supply pipe is leaking somewhere between the meter and the building. Walk its likely route and look for water coming up through joints in the tarmac, a patch of concrete that never dries or grass that stays green in a dry spell. Do not expect to see much, though. Under a yard built to carry lorries, a leak can run for months without showing on the surface. Finding it is a job for acoustic listening, leak-noise correlation and tracer gas, followed by a targeted excavation once the spot is known. How ADI investigates water mains and yard supplies.
Turning the meter reading into litres
Water meters read in cubic metres, and one cubic metre is 1,000 litres. A leak of 20 litres an hour sounds small. Left running, it is 480 litres a day and more than 14 cubic metres a month, on a site where nobody has turned on a single tap.
When to call
Call when the meter turns with everything you can find switched off, when it turns with the stopcock closed, or when you would rather an engineer did the checks with the right instruments. Tell the office what you found at each step; it goes straight into the quote and the engineer's plan for the day.