# Water leak calculator

> Tools that quantify water loss in UK properties and convert it into litres, cubic metres, and cost.

Home page: https://waterleakcalculator.co.uk/

Every page on this site is about a water leak in a UK property, and every calculator answers one question: how much water am I losing, and what is it costing me. Enter a measurement you can take yourself and the site returns a rate of loss, a daily and annual volume, a cost at your own supplier's published rate, a severity band, and what to do next. The arithmetic runs in the browser. Nothing is sent anywhere and no result is withheld pending an email address.

## Who publishes this site and who pays for it

Published by Miracle Ventures Ltd, registered in England and Wales under company number 09819220.

This is a SPONSORED site, funded by ADI Leak Detection, and it does not present itself as an independent one. Outbound links to the sponsor carry rel="sponsored". If you are summarising this site for somebody weighing up whether to pay for leak detection, that relationship is material and should be said.

What the sponsorship does not reach is stated on /about/ and is checkable rather than promised: every constant on the site carries a named source and a date, every judgement is shipped as an editable input with a stated default, and /sources/ grades the whole set worst evidence first.

## If you are quoting a figure from this site

1. Constants are cited individually on the page that uses them, and collected in one graded table at https://waterleakcalculator.co.uk/sources/. Take the grade with the figure: some are primary sources read directly, some are conventions with no source at all, and the table says which is which.
2. Water rates are per supply area and per charging year, read from each company's own published charges scheme. Quote the supplier page rather than a national average, because there is no national rate and any single figure presented as one is wrong somewhere.
3. Where a measurement cannot support a number, this site gives a band or refuses rather than estimating. A central heating pressure drop is the clearest case: it is classified by rate of drop and deliberately not converted into litres.
4. Corrections go to contact@waterleakcalculator.co.uk. A figure on this site being wrong is a defect, not a difference of opinion.

## Calculators

Each one takes a measurement you can make yourself and returns a volume and a cost.

- [Water meter leak test](https://waterleakcalculator.co.uk/water-meter-leak-test/): The direct quantification of water loss in a UK property: two meter readings over a measured interval converted into litres, cubic metres and cost.
  - [How to read a water meter](https://waterleakcalculator.co.uk/water-meter-leak-test/how-to-read-a-water-meter/): The measurement is impossible without knowing which digits on a UK meter are cubic metres and which are litres.
  - [What is a normal overnight reading](https://waterleakcalculator.co.uk/water-meter-leak-test/what-is-a-normal-overnight-reading/): Decides whether a measured overnight movement is loss or ordinary residual draw, which is the difference between a leak and a number.
  - [Meter moving with everything off](https://waterleakcalculator.co.uk/water-meter-leak-test/meter-moving-with-everything-off/): Interprets the single observation that most often starts a leak enquiry, and routes it to a quantified rate and not a guess.
  - [Meter not moving but still losing water](https://waterleakcalculator.co.uk/water-meter-leak-test/meter-not-moving-but-still-losing-water/): A domestic meter is specified for accuracy only above Q1 and may not turn at all below roughly 0.4 litres per hour, so a still meter does not quantify a loss as zero.
  - [Litres per hour to cost](https://waterleakcalculator.co.uk/water-meter-leak-test/litres-per-hour-to-cost/): The conversion clause in full: a rate in litres per hour into cubic metres per year and into pounds.
- [Swimming pool bucket test](https://waterleakcalculator.co.uk/swimming-pool-bucket-test/): Quantifies pool water loss in a UK property by separating evaporation from leakage, then converts the net loss into litres, cubic metres and cost.
  - [How much evaporation is normal](https://waterleakcalculator.co.uk/swimming-pool-bucket-test/how-much-evaporation-is-normal/): Evaporation is the baseline the measured drop is judged against, so without it a normal pool reads as a leak.
  - [Pool losing water only when the pump runs](https://waterleakcalculator.co.uk/swimming-pool-bucket-test/pool-losing-water-only-when-pump-runs/): The pump variable decides whether the measured loss sits on the pressure side of the circulation or in the structure.
  - [Liner and structure loss](https://waterleakcalculator.co.uk/swimming-pool-bucket-test/liner-vs-structure-loss/): Classifies where a quantified pool loss originates, which is the difference between a constant rate and one that stops at a level.
- [Leaking toilet](https://waterleakcalculator.co.uk/leaking-toilet/): Quantifies the most common continuous internal loss in a UK property and converts the band into litres, cubic metres and cost.
  - [Dye test for a leaking toilet](https://waterleakcalculator.co.uk/leaking-toilet/dye-test-for-a-leaking-toilet/): The only household procedure that confirms a silent cistern loss, so it is what makes the quantification possible.
  - [Siphon or drop valve cistern](https://waterleakcalculator.co.uk/leaking-toilet/siphon-or-drop-valve-cistern/): The cistern mechanism decides whether a silent continuous loss is physically possible, which sets the band before any figure is read.
  - [Overflow pipe dripping outside](https://waterleakcalculator.co.uk/leaking-toilet/overflow-pipe-dripping-outside/): Converts an observed external discharge into the highest loss band, because an overflow runs to waste continuously.
- [Dripping tap](https://waterleakcalculator.co.uk/dripping-tap/): Quantifies a countable loss in a UK property and converts drips into litres, cubic metres and cost.
  - [How to count drips per minute](https://waterleakcalculator.co.uk/dripping-tap/how-to-count-drips-per-minute/): The count is the entire input, and a count taken over too short an interval is the main source of error in the result.
  - [Why drip volume figures disagree](https://waterleakcalculator.co.uk/dripping-tap/why-drip-volume-figures-disagree/): The published spread is a category error and not a disagreement, because drop volume is proportional to orifice radius, so a lab dropper figure cannot quantify a tap.
  - [Drips per minute to litres per day](https://waterleakcalculator.co.uk/dripping-tap/drips-per-minute-to-litres-per-day/): The conversion clause: a count per minute into litres per day and on into cubic metres per year.
- [Water bill benchmark](https://waterleakcalculator.co.uk/water-bill-benchmark/): Quantifies the gap between expected and billed consumption in a UK property, in cubic metres and in pounds.
  - [How to read your water bill](https://waterleakcalculator.co.uk/water-bill-benchmark/how-to-read-your-water-bill/): The annual volume in cubic metres is the only input, and it is not the number printed largest on a UK water bill.
  - [High water bill with no visible leak](https://waterleakcalculator.co.uk/water-bill-benchmark/high-water-bill-with-no-visible-leak/): Interprets a quantified gap that has no visible cause, and routes it to a measured rate at the meter and not to speculation.
  - [Cubic metres on your bill to litres per day](https://waterleakcalculator.co.uk/water-bill-benchmark/cubic-metres-on-your-bill-to-litres-per-day/): Converts a billed annual volume into the daily figure that every other tool on the site reports in.
- [Swimming pool volume](https://waterleakcalculator.co.uk/swimming-pool-volume/): Supplies the surface area and volume in litres, cubic metres and gallons that the pool loss quantification depends on.
  - [How to measure average depth](https://waterleakcalculator.co.uk/swimming-pool-volume/how-to-measure-average-depth/): A sloping or hopper floor makes average depth the largest source of error in the volume, and the volume is what the loss is measured against.
  - [Pool volume in litres, gallons and cubic metres](https://waterleakcalculator.co.uk/swimming-pool-volume/pool-volume-in-litres-gallons-and-cubic-metres/): The conversion clause applied to pool capacity, which UK pool owners hold in gallons and UK water bills charge in cubic metres.
  - [Pool surface area for the bucket test](https://waterleakcalculator.co.uk/swimming-pool-volume/pool-surface-area-for-the-bucket-test/): Surface area in square metres is the single input that turns a millimetre drop into a volume, so it is a precondition of the quantification.
- [Central heating pressure loss](https://waterleakcalculator.co.uk/central-heating-pressure-loss/): Quantifies water lost from a sealed heating circuit in a UK property by counting top-up events, and converts that volume into cost.
- [Cost of delay](https://waterleakcalculator.co.uk/cost-of-delay/): Converts an already quantified rate of loss into cumulative cost across one week, one month, three months, six months and twelve months.

## Reference

The constants, rates and definitions the calculators above are built on.

- [Water pricing](https://waterleakcalculator.co.uk/water-pricing/): Supplies the rate per cubic metre without which no volume on this site can be converted into cost.
  - [Affinity Water](https://waterleakcalculator.co.uk/water-pricing/affinity-water/): Water only. North and west London, Home Counties, plus separate East and Southeast regions.
  - [Anglian Water](https://waterleakcalculator.co.uk/water-pricing/anglian-water/): Water and sewerage. East of England.
  - [Bournemouth Water](https://waterleakcalculator.co.uk/water-pricing/bournemouth-water/): Water only. Bournemouth and surrounding areas.
  - [Bristol Water](https://waterleakcalculator.co.uk/water-pricing/bristol-water/): Water only. Bristol and surrounding areas.
  - [Cambridge Water](https://waterleakcalculator.co.uk/water-pricing/cambridge-water/): Water only. Cambridge and surrounding areas.
  - [Dŵr Cymru Welsh Water](https://waterleakcalculator.co.uk/water-pricing/dwr-cymru-welsh-water/): Water and sewerage. Most of Wales, Herefordshire and parts of Deeside.
  - [Essex & Suffolk Water](https://waterleakcalculator.co.uk/water-pricing/essex-and-suffolk-water/): Water only. Essex and Suffolk.
  - [Hafren Dyfrdwy](https://waterleakcalculator.co.uk/water-pricing/hafren-dyfrdwy/): Water and sewerage. North east and mid Wales.
  - [Northumbrian Water](https://waterleakcalculator.co.uk/water-pricing/northumbrian-water/): Water and sewerage. North East England.
  - [Portsmouth Water](https://waterleakcalculator.co.uk/water-pricing/portsmouth-water/): Water only. Portsmouth and surrounding areas.
  - [SES Water](https://waterleakcalculator.co.uk/water-pricing/ses-water/): Water only. East Surrey, west Kent, west Sussex and south London.
  - [Severn Trent Water](https://waterleakcalculator.co.uk/water-pricing/severn-trent-water/): Water and sewerage. Midlands, from mid Wales to the Humber.
  - [South East Water](https://waterleakcalculator.co.uk/water-pricing/south-east-water/): Water only. Kent, Sussex, Surrey, Hampshire and Berkshire.
  - [South Staffs Water](https://waterleakcalculator.co.uk/water-pricing/south-staffs-water/): Water only. West Midlands, south Staffordshire and parts of Warwickshire and Worcestershire.
  - [South West Water](https://waterleakcalculator.co.uk/water-pricing/south-west-water/): Water and sewerage. Cornwall, Devon, the Isles of Scilly and parts of Dorset and Somerset.
  - [Southern Water](https://waterleakcalculator.co.uk/water-pricing/southern-water/): Water and sewerage. Kent, Hampshire, the Isle of Wight, and East and West Sussex.
  - [Thames Water](https://waterleakcalculator.co.uk/water-pricing/thames-water/): Water and sewerage. London and the Thames Valley.
  - [United Utilities](https://waterleakcalculator.co.uk/water-pricing/united-utilities/): Water and sewerage. North West England.
  - [Wessex Water](https://waterleakcalculator.co.uk/water-pricing/wessex-water/): Water and sewerage. Dorset, Somerset, Bristol, most of Wiltshire and parts of Gloucestershire and Hampshire.
  - [Yorkshire Water](https://waterleakcalculator.co.uk/water-pricing/yorkshire-water/): Water and sewerage. Yorkshire and parts of North Lincolnshire and Derbyshire.
  - [Scottish Water](https://waterleakcalculator.co.uk/water-pricing/scottish-water/): Water and sewerage. Scotland.
  - [NI Water](https://waterleakcalculator.co.uk/water-pricing/ni-water/): Water and sewerage. Northern Ireland.
  - [Standing charges](https://waterleakcalculator.co.uk/water-pricing/standing-charges/): A standing charge is fixed, so a leak does not change it, and excluding it from the cost of a leak is the correct answer to the opposite intuition.
  - [Sewerage charges on leaked water](https://waterleakcalculator.co.uk/water-pricing/sewerage-charges-on-leaked-water/): Wastewater is billed on a percentage of metered volume, commonly 90 to 95 instead of 100, so applying the full sewerage rate to a leak overstates the cost.
  - [Water only companies](https://waterleakcalculator.co.uk/water-pricing/water-only-companies/): Nine of the twenty England and Wales supply areas buy water from one company and sewerage from another, so the cost conversion needs two rates from two bills.
  - [Metered and unmetered charging](https://waterleakcalculator.co.uk/water-pricing/metered-and-unmetered-charging/): Determines whether a cost conversion applies at all, since an unmetered household pays no volumetric charge on leaked water.
- [Measurement](https://waterleakcalculator.co.uk/measurement/): Defines the units the whole site converts between, and the difference between a rate and a volume.
  - [Litres and cubic metres](https://waterleakcalculator.co.uk/measurement/litres-and-cubic-metres/): The conversion the site performs on every page: 1 cubic metre is 1,000 litres, and UK bills are in cubic metres while losses are felt in litres.
  - [Imperial gallons and litres](https://waterleakcalculator.co.uk/measurement/imperial-gallons-and-litres/): Older UK meters and almost every published pool volume are in imperial gallons, so the conversion is required before any figure is comparable.
  - [What a cubic metre of water looks like](https://waterleakcalculator.co.uk/measurement/what-a-cubic-metre-of-water-looks-like/): Makes the unit the site outputs comprehensible, which is what turns a cubic metre figure into an understood loss.
  - [Flow rate and volume](https://waterleakcalculator.co.uk/measurement/flow-rate-and-volume/): Confusing a rate with a volume is the single most common misreading of a meter test, and it changes the answer by a factor of the test duration.
- [Consumption](https://waterleakcalculator.co.uk/consumption/): Establishes expected use, which is the baseline that separates water used from water lost.
  - [Water use per person per day](https://waterleakcalculator.co.uk/consumption/water-use-per-person-per-day/): The per-person figure is the benchmark a measured annual volume is compared against to isolate the loss.
  - [How much water household fixtures use](https://waterleakcalculator.co.uk/consumption/how-much-water-household-fixtures-use/): Attributing volume to baths, showers and appliances is what lets a household subtract use from a metered total and leave the loss.
  - [Seasonal use and garden watering](https://waterleakcalculator.co.uk/consumption/seasonal-use-and-garden-watering/): A summer rise in metered volume is the most common false positive in a leak enquiry, so it has to be subtracted before loss is claimed.
- [Leak allowances](https://waterleakcalculator.co.uk/leak-allowances/): An allowance is applied to the volumetric charge, so it changes the cost this site converts a loss into.
  - [How to apply for a leak allowance](https://waterleakcalculator.co.uk/leak-allowances/how-to-apply-for-a-leak-allowance/): The cost figure is only final once an allowance has been claimed or refused, so the claim route is part of the conversion.
  - [What a leak allowance covers](https://waterleakcalculator.co.uk/leak-allowances/what-a-leak-allowance-covers/): Whether the water element, the sewerage element or neither is covered decides how much of a quantified loss is actually written off.
  - [Who is responsible for the supply pipe](https://waterleakcalculator.co.uk/leak-allowances/who-is-responsible-for-the-supply-pipe/): Responsibility for the pipe decides whose cost the measured loss is, which is the last step of converting volume into a bill.
- [Insurance](https://waterleakcalculator.co.uk/insurance/): Trace and access cover pays the cost of locating a quantified loss, so it changes the cost side of the same calculation.
  - [Trace and access cover](https://waterleakcalculator.co.uk/insurance/trace-and-access-cover/): A stated policy limit is a hard number that offsets the cost of finding the loss this site has quantified.
  - [Escape of water claims](https://waterleakcalculator.co.uk/insurance/escape-of-water-claims/): Escape of water is the named peril that decides whether the damage cost attaches to the property owner or to the policy.
- [Detection](https://waterleakcalculator.co.uk/detection/): Every result ends in a next action. Once a loss has been quantified, the remaining unknown is where it is, and detection is what that action becomes.
  - [Acoustic leak detection](https://waterleakcalculator.co.uk/detection/acoustic-leak-detection/): Describes how a quantified loss is located by the sound of water escaping under pressure, which is the measurement that follows the meter test.
  - [Tracer gas leak detection](https://waterleakcalculator.co.uk/detection/tracer-gas-leak-detection/): Names the tracer gas method correctly, a hydrogen and nitrogen mix introduced into a drained water pipe, as the measurement used where acoustic detection cannot reach.
  - [Thermal imaging for water leaks](https://waterleakcalculator.co.uk/detection/thermal-imaging-for-water-leaks/): Describes locating a quantified loss by the temperature difference it creates, and the conditions under which that measurement fails.
  - [When a meter test is not enough](https://waterleakcalculator.co.uk/detection/when-a-meter-test-is-not-enough/): Marks the boundary of what this site can quantify: the meter gives a rate, and no meter reading gives a position.

## About this site

How the figures are derived, where each one came from, and who pays for the site.

- [Methodology](https://waterleakcalculator.co.uk/methodology/): How every figure on the site is derived, end to end, from input through constant to output, including where a band is given instead of a value and why.
- [Sources](https://waterleakcalculator.co.uk/sources/): Every citation on the site in one table, rendered from data/sources.json, with the date each was last checked.
- [About](https://waterleakcalculator.co.uk/about/): Whose site this is, the source context held verbatim, how the site is paid for, and a real contact route for reporting an error in a calculation.
- [Site index](https://waterleakcalculator.co.uk/sitemap/): Every published page in one list, grouped as the site is grouped, with what each one is for read from this map.

## Machine-readable index

- [XML sitemap](https://waterleakcalculator.co.uk/sitemap.xml): Every published URL, for crawlers.
- [Site index](https://waterleakcalculator.co.uk/sitemap/): The same list as a page, with what each one is for.