Water Bill Calculator
Estimate your UK water and sewerage bill for 2025/26. Compare metered vs unmetered charges across 11 regional water companies, find out if a meter would save you money, and discover simple ways to reduce your bill.
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How to Use This Calculator
My Water Bill tab
Select your water company from the dropdown (there are 11 companies covering England, Wales, and Scotland). Choose whether you are on a metered or unmetered bill. For metered customers, enter the number of people in your household or your actual usage in cubic metres per year. For unmetered customers, enter your property's rateable value (found on your water bill). The calculator shows your annual water supply, sewerage, and standing charges.
Metered vs Unmetered tab
Enter your rateable value, number of occupants, and property type. The calculator compares both billing methods side by side and recommends which is cheaper for your situation. As a rule of thumb, if the number of bedrooms exceeds the number of people living in the property, a meter usually saves money.
Reduce Your Bill tab
Enter your current annual water bill and household size. The calculator estimates annual savings for 10 water-saving measures — from free changes (shorter showers, turning off taps) to small investments (water butts, efficient showerheads). It also shows WaterSure eligibility information for families on benefits with medical needs or 3+ children.
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The Formula
Your water bill is calculated differently depending on whether you have a water meter:
Water supply = (Usage in m³ × Water rate per m³) + Annual standing charge
Sewerage = (Usage in m³ × 0.95 × Sewerage rate per m³) + Annual standing charge
Total annual bill = Water supply + Sewerage
Unmetered bill:
Water supply = Rateable value × Water poundage rate
Sewerage = Rateable value × Sewerage poundage rate
Total annual bill = Water supply + Sewerage
Usage conversion:
m³/year = People × Litres/person/day × 365 ÷ 1,000
For metered customers, the sewerage charge is applied to 95% of the metered water supply. The assumption is that 5% of water is used outdoors (gardens, car washing) and does not enter the sewerage system.
For unmetered customers, the charge is based on the rateable value (RV) of your property. Rateable values were set in 1990 and have not been updated since. The water company multiplies your RV by a pence-in-the-pound rate to calculate your bill.
Both metered and unmetered customers also pay standing charges — fixed annual amounts that cover the cost of maintaining the water network, regardless of usage.
Example
James — Accountant, 38, Birmingham (Severn Trent Water)
James lives in a 3-bedroom semi-detached house with his partner. They are on a water meter and use a typical amount of water.
My Water Bill tab
James's bill is £102 below the national average of £603. This is because he has a water meter and only 2 people in the household.
Metered vs Unmetered tab
If James's property has a rateable value of £250, his unmetered bill would be approximately £516. With a meter, he pays £501 — saving £15/year. The saving is modest because there are only 2 occupants, but it grows significantly if the RV is higher or usage is below average.