1. Published regional averages
Our starting dataset is Water UK’s forecast annual average bill changes for 2026/27, effective from 1 April 2026. It covers 11 combined water and wastewater companies and 11 water-only company regions. The national average is £639.
2. Household consumption
For a typical-use selection, we model approximately 120 litres per person per day. “Careful” and “higher” settings apply factors around that baseline. Actual use is affected by property, appliances, occupancy, showers, baths, toilets and outdoor watering.
3. From company average to household estimate
Company averages include a mixture of metered and unmetered homes. To produce a household estimate, we separate an indicative fixed share from a consumption-linked share and apply a sub-linear occupancy factor. This reflects shared use: two people do not necessarily use exactly twice as much as one.
4. Postcode matching
We use postcode-area prefixes to suggest the most likely combined regional company. Boundaries do not exactly follow postcode areas and a water-only company may supply clean water while another company handles wastewater. The match is therefore labelled “likely” and the bill remains authoritative.
5. What we do not claim
- The result is not a quote or a substitute for a company tariff calculation.
- We do not currently model every charging zone, standing charge, rateable value or surface-water rebate.
- We do not use the estimate as grounds to challenge a supplier.
- Business-water figures require site-specific wholesale and retail charges.
Sources
- Water UK: annual average bill changes 2026/27
- CCW: water meter calculator and consumer guidance
- Ofwat: business retail market
Corrections and updates
We review the shared tariff-year dataset when new annual company averages are published and record the review date on factual pages. If you spot an error, please contact us with the source and affected page.