How to check for a water leak at a business property
A free five-minute meter test for UK businesses. Confirm whether you have a hidden water leak, estimate what it is costing you per year, and see exactly what to ask your retailer next. No sign-up, no email capture, no AI guesswork. The test follows the same procedure used by professional leak detection engineers.
In a hurry? If your meter is moving with every tap, toilet and appliance switched off, you have a leak. Skip to the calculator or read the full method.
The 5-minute leak calculator
Take two meter readings with no water in use between them. Enter them below. The calculator returns the leak flow rate, the probable cost per year, and the next steps to take.
Read to three decimal places if your meter allows.
Taken after at least 30 minutes of no water use.
Minimum 30 minutes. One hour is recommended.
Sets the unit rate used in the cost estimate.
Calculator outputs are indicative. The combined £/m³ used for the cost estimate is a 2025-26 wholesale + indicative retail-margin figure for the selected area; your contracted rate may differ. Source: regional wholesaler 2025-26 Charging Schemes, Purely Energy internal benchmark, retrieved 2026-05-16.
The full meter test method
1. Turn off every water-using fixture
Every tap, toilet, washing machine, dishwasher, ice maker, urinal flush, drinking fountain, cooling tower top-up and irrigation valve. Keep the internal stop tap open so any leak shows up at the meter.
2. Read the meter and note the time
Read to three decimal places, in cubic metres. Take a phone photo of the dial as a backup. Note the exact time, to the minute. A retailer will not accept a leak claim that does not have time-stamped before/after readings.
3. Wait at least 30 minutes with no water use
One hour is better, especially for multi-unit buildings where a toilet cistern can refill on a slow drift. Two hours catches the slowest of pinhole leaks. Use the longest window the building can spare.
4. Take the second reading at the same precision
Any movement is suspicious. A visible move on the main register is a leak. A turning low-flow dial (the small dial, often a star or triangle) with no visible main-register move is a small but real leak.
5. Run the readings through the calculator
The calculator above will estimate the leak as a flow rate (litres per minute) and as an annual cost using a regionally accurate wholesale plus retail unit rate. It will also tell you exactly what to ask your retailer next.
Why this matters for UK businesses
Roughly one in ten non-household water meters in England is on a smart connection. The other nine in ten are read manually or estimated. A leak on an estimated-read site can run for months before it appears on a bill, and the bill that finally arrives includes both the leaked water and the wastewater charge on that volume (because most wholesalers default to charging sewerage on every cubic metre of metered supply unless you prove otherwise).
The market is in the middle of a regulatory reset. Ofwat is reviewing the Retail Exit Code (REC) protections that price most business water customers, and the new Market Performance Framework that came into effect on 1 April 2026 puts harder service-level incentives on retailers and wholesalers. A documented leak detection is one of the few things that can translate cleanly into a billing credit under both regimes.
For the wider regulatory backdrop, our Energy Hub tracks every change in the non-household water market. If you think your retailer is mis-billing you on a leak, our business water team handles disputes for portfolios of every size.
Frequently asked questions
+How do I know if I have a water leak at my business premises?
The cleanest test is a meter test. Turn every water fixture off, read the meter, wait 30 to 60 minutes, then read again. If the second reading is higher, you have a leak somewhere between the meter and the building. The calculator on this page sizes the leak and estimates the annual cost.
+Who pays for a water leak on a business property?
Responsibility splits at the boundary stop tap. The wholesaler (Thames, Severn Trent, Anglian and so on) is responsible for the mains pipe up to that point; the business is responsible for everything from the stop tap into the building. Some retailers offer leak allowances if a hidden leak inside the boundary has been fixed within a set window.
+Can my water retailer claim back the cost of a leak from the wholesaler?
Yes, where the leak was on the wholesaler-owned section of pipe. The retailer raises a wholesaler charge dispute through MOSL's Central Market Operating System (CMOS). The customer usually does not deal with the wholesaler directly. Document everything from the moment you notice the leak and ask the retailer for an explicit leak allowance review.
+What is a continuous flow on a water meter?
A continuous flow is water passing through the meter when nothing in the building should be using water. Smart meters detect it automatically and many retailers raise an alert. On a traditional meter, the small low-flow dial will turn slowly when there is a continuous flow, even with the building shut up.
+How much does a small water leak cost a business per year?
A pinhole leak losing 1 litre per minute runs to roughly 525,000 litres per year, or about 525 cubic metres. At a typical UK wholesale water and wastewater unit rate of around 2.50 to 3.50 pounds per cubic metre combined, that is between 1,300 and 1,850 pounds per year, plus any standing charges. The calculator on this page works it out for your region.
+Should I report a suspected leak to my water retailer or the wholesaler?
Always your retailer first. The retailer is your single point of contact for the non-household water market and will escalate to the wholesaler if the leak is on the wholesaler-owned section of pipe. If the leak is causing visible damage or a flood, also call 0800 80 70 60 (the leakline shared by most English wholesalers) and your insurer.
Think your retailer has billed you for a leak?
Send us the meter readings and a sample bill. We will tell you, inside two working days, whether there is a leak allowance to chase.
Get a free leak review