Litres per hour to cost
A loss of one litre per hour is 8.76 cubic metres a year. That single figure does the whole conversion: multiply your rate of loss in litres per hour by 8.76 for the annual volume in cubic metres, then by your supplier volumetric rate for the annual cost.
Last reviewed 14 August 2026
The short answer
Multiply the rate of loss in litres per hour by 8.76 to get cubic metres a year, then by your supplier volumetric rate to get pounds a year.
| Rate of loss | Per day | Per year |
|---|---|---|
| 0.5 L/hr | 12 litres | 4.38 m³ |
| 1 L/hr | 24 litres | 8.76 m³ |
| 5 L/hr | 120 litres | 43.8 m³ |
| 10 L/hr | 240 litres | 87.6 m³ |
| 60 L/hr | 1,440 litres | 525.6 m³ |
That table is arithmetic, not estimation. Every row is the rate multiplied by 24 and by 365, and divided by 1,000.
The figures above are exact, so you can check them. The calculators round annual volume to one decimal place when they display it, which means the tool shows 8.8 where this table shows 8.76. That is a display choice rather than a disagreement, and the exact factor is given here because it is the one you need if you are working it out by hand.
How this works in practice
Four steps, and only the last one needs a number you do not already have.
- Rate to daily volume: multiply by 24.
- Daily volume to annual volume in litres: multiply by 365.
- Litres to cubic metres: divide by 1,000. UK water is billed in cubic metres and losses are felt in litres, so this step is unavoidable.
- Annual volume to cost: multiply by the volumetric rate your supplier charges per cubic metre, plus the sewerage rate only if the water reaches the sewer.
The first three steps are definitional and identical for everyone. The fourth is the only one that varies, and the rate per cubic metre your supplier charges is where those rates live, each with the date it was published. converting litres to cubic metres covers the unit step on its own if that is all you need.
What changes the answer
Four things, and three of them push the number down rather than up.
- Whether the sewerage rate applies. This is the largest single factor, because the sewerage rate is often comparable to the water rate, so getting it wrong can nearly double or halve the answer. It applies to an internal leak that drains away and not to an underground supply pipe loss that soaks into the ground.
- The share of metered volume your company bills wastewater on. Companies do not all bill the full volume, and some price the allowance into the rate instead. The calculator uses the figure for your own supplier rather than assuming the whole volume.
- The standing charge, which does not apply at all. It is fixed, so it belongs in the bill and not in the cost of a leak.
- Whether a volumetric charge applies to you at all. An unmetered household pays none, so a leak does not change the bill, and neither does one in an unmetered Scottish property or a Northern Irish domestic one.
A leak allowance, where one is granted, is applied afterwards to the volumetric charge. It changes the bill rather than the loss, and the volume above is unaffected by it.
Assumptions and sources
Litres in a cubic metre
Exact by definition
SI definition. The litre is defined as one cubic decimetre, so one cubic metre is exactly 1,000 litres.
Hours in a day
Exact by definition
Definition of the day as 24 hours.
Days used for an annual figure
Editorial convention
Annual figures on this site are a daily rate multiplied by 365. Leap years are not modelled, so a leap year is understated by one day, which is 0.27 per cent.
Where the first severity band ends
Editorial convention
A practical threshold set just above the 0.4 litres per hour starting flow quoted for a DN15 meter with the TVM register. It is not a meter accuracy tolerance. Against the STANDARD it sits about 31 times below Q1, the 15.6 litres per hour at which OIML R 49-1 first defines any permitted error. Against THIS MANUFACTURER it sits about 6 times below 3 litres per hour, the lowest flow at which Itron volunteers a typical accuracy that the standard does not require. Neither figure reaches down to 0.5, so nothing quantifies a reading here on either footing. Meters with other registers start higher, so this threshold sits above the most sensitive case rather than above every meter.
The volume conversion carries no assumption and needs no source. It is 24 hours, 365 days, and 1,000 litres to a cubic metre. A leap year makes the annual figure about 0.3 per cent higher, which is smaller than the error in any household meter reading and is not corrected for.
The cost step deliberately carries no worked example. No supplier tariff on this site has been verified yet, every record is marked unverified and renders a notice rather than a figure, and a worked example built on an invented rate would be the most quotable wrong number on the site.
What to do next
With an annual volume in cubic metres, three things become checkable.
- Compare it against your own bill. A loss of 43.8 cubic metres a year is a large share of a typical household total, and if your billed volume has not risen by roughly that much, the rate you measured may not have been running all year.
- Check whether the sewerage element should be included before you use the figure for anything. It is the difference between two quite different numbers.
- Keep the measured rate and the dates. Those are what a leak allowance claim is assessed on, and an allowance is applied to exactly the volumetric charge this conversion produces.
Common questions
- Where does 8.76 come from?
- It is 24 hours multiplied by 365 days, divided by the 1,000 litres in a cubic metre. There is no assumption in it and nothing to disagree with.
- Should I add the sewerage rate as well?
- Only if the leaking water reaches the sewer. Water lost from an underground supply pipe soaks into the ground and never enters the sewerage system, so applying the sewerage rate to it overstates the cost, often close to doubling it. Water from an internal leak usually does reach the sewer.
- Does the standing charge go up?
- No. A standing charge is fixed and does not move with the volume you use, so a leak does not change it. Only the volumetric charge responds, which is why it is the only part of the bill this conversion uses.
- Why is there no worked example with a real rate in it?
- Because no supplier tariff on this site has been verified yet. Every record is marked unverified and shows a notice instead of a figure. A worked example with an invented rate would be the most quotable wrong number here, and inventing one to make a page look finished is the failure this site exists to avoid.
- Does this work in Scotland or Northern Ireland?
- The volume conversion does, and it is the same everywhere. The cost step does not. Unmetered household charges in Scotland are set by Council Tax band and collected by the council, so the bill does not move when water is lost, and domestic water in Northern Ireland is not charged to households at all. In both cases the honest annual cost of a leak is not zero pounds by coincidence, it is that no volumetric charge applies.