Water Bill Calculator
Estimate a UK metered household water bill using daily usage, separate water and wastewater tariffs, standing charges and drainage fees. See annual, monthly and per-person costs, compare with your current bill and explore savings from using less water.
Important billing note
This calculator estimates a metered household bill. Unmetered bills are usually based on your property’s rateable value rather than actual litres used, and assessed charges use company-specific rules. Always replace the example values with the tariffs and fixed charges shown on your own bill.
Calculator
Example values are pre-filled so you can see how the calculator works. Enter the exact figures from your water company for a meaningful estimate.
Total litres used by everyone in the property each day.
Used for per-person usage and cost comparisons.
The metered clean-water rate shown in £ per cubic metre.
The sewerage volumetric rate, if it appears separately on your bill.
Some companies bill wastewater on less than 100% of metered water.
Enter your present metered or unmetered total for comparison.
Annual fixed charges
Use the yearly totals from your tariff sheet or bill. Leave a field at £0 if it does not apply or is already included elsewhere.
Daily usage estimator
Not sure about your litres per day? Enter approximate household-wide daily quantities. Appliance and flow-rate figures are broad examples, so a meter reading is more reliable.
Usage in context
Personalised interpretation
Potential savings from lower usage
These scenarios reduce the volumetric water and wastewater charges only. Fixed standing and drainage charges stay unchanged.
How the water bill estimate is calculated
A metered bill normally combines charges based on the volume used with one or more fixed charges. Water companies publish their own charging schemes, so the rates and labels on your bill may differ.
One cubic metre (m³) equals 1,000 litres. A tariff of £2.00 per m³ is therefore equivalent to 0.2 pence per litre.
Scope: this formula is intended for a straightforward household metered estimate. It does not model every company-specific discount, social tariff, WaterSure cap, leak allowance, seasonal tariff, assessed charge, surface-water rebate or compulsory metering rule.
Worked example
A two-person household uses 300 litres per day. Its water rate is £2.00 per m³, wastewater rate is £2.50 per m³, and the company bills wastewater on 90% of metered water. Annual fixed charges total £160.
- Annual water volume: 300 × 365 ÷ 1,000 = 109.5 m³.
- Water supply charge: 109.5 × £2.00 = £219.00.
- Wastewater volume: 109.5 × 90% = 98.55 m³.
- Wastewater charge: 98.55 × £2.50 = £246.38.
- Total: £219.00 + £246.38 + £160.00 = £625.38 per year, or about £52.11 per month.
Metered, unmetered and assessed water bills
Metered bill
Usually combines a fixed standing charge with volumetric charges for water and wastewater. This is the bill type the calculator estimates.
Unmetered bill
Usually includes a fixed charge and a charge linked to the property’s historic rateable value. Using less water normally does not directly reduce this type of bill.
Assessed charge
May be offered when a requested meter cannot reasonably be fitted. The company may use factors such as occupants, bedrooms, property type or local average bills.
Where to find the figures on your bill
- •Metered consumption: look for cubic metres used during the billing period. Subtract the previous meter reading from the latest reading if the bill does not show the difference clearly.
- •Water tariff: usually shown as a price per cubic metre next to the clean-water or water-supply charge.
- •Wastewater tariff: may appear as sewerage, foul sewerage or used-water charge. Your sewerage provider may be different from your water provider.
- •Return-to-sewer allowance: some bills assume that a percentage of supplied water does not return to the sewer. Use the exact percentage in the charging scheme.
- •Fixed charges: add annual water, wastewater, surface-water drainage and any other fixed charges without counting the same item twice.
Practical ways to reduce a metered water bill
Check for hidden leaks
Turn off water-using appliances and check whether the meter continues to move. Contact your water company before arranging invasive work, as leak policies differ.
Reduce shower time
Showers can be a major part of household use. A lower-flow shower head or a few minutes less per shower can reduce both water and hot-water energy use.
Run full appliance loads
Use washing machines and dishwashers with full loads where appropriate and choose efficient programmes rather than running extra partial cycles.
Review drainage charges
A property whose rainwater does not drain into the public sewer may qualify for a surface-water drainage rebate, subject to the company’s criteria.
Common questions
Does this calculate an unmetered bill?⌄
Why is wastewater charged separately?⌄
What does “return to sewer” mean?⌄
How many litres are in one cubic metre?⌄
Would a water meter save me money?⌄
Can I switch back after fitting a meter?⌄
Sources and assumptions
This calculator is an independent budgeting tool for household use. It does not reproduce any individual water company’s full charging scheme and should not be used to dispute an official bill.
- Geographic scope: the supporting guidance is mainly for household customers in England and Wales. Scotland and Northern Ireland use different billing arrangements.
- Usage benchmark: the page uses approximately 140 litres per person per day as a broad comparison point. Actual household use varies significantly with occupancy, appliances, leaks, garden use and behaviour.
- Billing structure: metered bills commonly include volumetric and standing charges for water and wastewater. Companies may also add surface-water drainage, highway drainage or other company-specific charges.
- Example inputs: the values pre-filled in the calculator are illustrative, not national tariffs. Always copy the rates from your own current bill or charging scheme.
- Wastewater allowance: the default 90% return-to-sewer figure is only an example. Some companies use a different allowance or charge structure.
- Rounding: calculations use unrounded values internally and display most money results to the nearest penny. A supplier may round individual bill lines differently.
- Limitations: the estimate excludes discounts, social tariffs, WaterSure, arrears, payment-plan adjustments, leak allowances, taxes where applicable, compulsory metering rules and company-specific special tariffs unless entered as fixed charges.
Useful official references
- Ofwat: household water bills and charging types
- Ofwat: metered customers and applying for a meter
- Ofwat: unmetered customers and rateable value
- Ofwat: assessed charges when a meter cannot be fitted
- Ofwat: surface-water drainage charges and rebates
- Consumer Council for Water: water meter calculator
- Water UK: household water-use research