Use this water bill calculator guide to estimate your business water and sewerage costs and understand how commercial water charges are calculated in the UK.
UK business water bills are not fixed. Charges vary by supplier, meter status, usage, wastewater type and tariff structure. This page explains how business water bills are built, what affects the cost, and how to estimate what your business should be paying — before deciding whether switching supplier makes sense.
Water cost: £0.00
Wastewater Cost: £0.00
Standing Charges: £0.00
Surface Drainage: £0.00
Highway Drainage: £0.00
Total Estimated Bill: £0.00
Annual charges are prorated to match the number of days entered, reflecting how suppliers bill over monthly or quarterly periods. Usage charges are in pence per m3.
How Are Business Water Bills Calculated?
UK water companies are allowed to set their own charging structures for non-household customers, within regulatory limits. Business water bills typically depend on:
- Whether your premises has a water meter
- How much water your business uses
- How much wastewater is discharged
- The type of wastewater produced
Charges are calculated differently for metered and unmetered businesses.
Metered Business Water Bills
If your business has a water meter installed, your bill normally includes:
- A standing charge (based on meter size)
- A volumetric charge (price per cubic metre of water used)
Standing charges vary by supplier and meter size. As standing charges are linked to meter size, not water usage — many businesses have oversized meters installed for historical reasons and may be paying unnecessarily high standing charges – we can resolve this.
Usage charges are applied to each cubic metre (m³) of water consumed during the billing period. One cubic metre of water is 1000 litres.
Unmetered Business Water Bills
If your business does not have a water meter, charges are calculated in a similar way to unmetered domestic properties.
These bills are not based on actual water use. Instead, they are built using:
- A fixed charge
- A charge linked to the rateable value of the premises
The rateable value of the property is a historic valuation set by the Valuation Office. This value is fixed and does not reflect actual water usage, which is why unmetered sites often benefit from installing a meter.
For small businesses, unit rates are often similar to domestic rates, with additional charges for customer service, billing and connection costs. These vary by supplier and region.
Sewerage Charges Explained
In addition to water supply, most businesses pay sewerage charges. These cover the treatment and collection of wastewater, including:
- Foul sewage – wastewater from toilets and sinks
- Surface water drainage – rainwater entering the public sewer
- Highway drainage – runoff from roads and pavements
- Trade effluent – wastewater produced by business or industrial processes
Foul sewage and trade effluent charges are usually based on volume and, in some cases, strength. Surface water and highway drainage charges are calculated differently depending on the supplier.
Note: Some industrial sites are charged for trade effluent strength (biological or chemical load). This calculator assumes standard strength wastewater and does not model strength-based surcharges.
If your business does not produce certain wastewater types, you may be eligible for reduced sewerage charges, subject to evidence.
Water Bill Changes and Switching Suppliers
Business water and sewerage charges are updated annually.
If another licensed water retailer offers more competitive pricing or a tariff better suited to your usage, most UK businesses are free to switch supplier.
Understanding how your bill is calculated makes it easier to identify whether switching is worthwhile.
What Is Ofwat?
Ofwat is the economic regulator of the water industry in England and Wales. It was established following the privatisation of the water sector.
Ofwat:
- Sets price limits for smaller businesses and households
- Oversees charging fairness across suppliers
- Investigates overcharging or misreporting
Businesses using less than 50 megalitres (Ml) of water per year are subject to Ofwat price limits. Larger users are charged differently, but pricing must still be non-discriminatory.
Business Water Tariffs Explained
Water suppliers offer different tariffs depending on usage patterns and demand.
Large and Intermediate User Tariffs
Businesses using high volumes of water (often 50,000 m³ or more per year) may qualify for specialist tariffs. These typically include:
- A standing charge
- A volumetric usage rate
Some tariffs apply lower unit rates after a usage threshold is reached. Others charge a fixed amount plus reduced per-unit pricing to discourage excessive consumption.
Seasonal Tariffs
Seasonal tariffs apply different rates at different times of year.
They are suited to businesses with predictable seasonal usage patterns and normally require a water meter.
Subscribed Demand Tariffs
Subscribed demand tariffs are designed for businesses that can accurately predict daily water usage.
They are built from:
- A maximum demand charge
- A standard usage rate up to the agreed limit
- A penalty rate for usage above the agreed demand
These tariffs reward accurate forecasting but penalise over-use.
Interruptible Tariffs
Interruptible tariffs offer reduced charges in exchange for agreeing to occasional supply interruptions. These tariffs suit businesses that can safely manage planned water outages.
Alternative and Non-Potable Water Supplies
Businesses with their own water supplies may still pay standby charges to their main supplier as insurance against supply failure. These usually include:
- A reserved volume charge
- A capacity charge based on maximum demand
Some suppliers also offer non-potable water for industrial use. This is charged in a similar way to potable water but at a lower cost per cubic metre.
Non-Standard Water Charges
Some charges are not usage-related and may appear separately on bills, including:
- Meter installation or testing
- Reconnection fees
- Standpipe hire
- Hydrant installation
These are monitored, but not price-capped, by Ofwat.
Your Water Bill – SPID (Supply Point Identifier)
A SPID (Supply Point Identifier) is the unique reference number used to identify your business water supply point. It’s effectively the “MPAN/MPRN equivalent” for water.
You’ll usually find your SPID on your water bill, often near the top or in the account details section, and it typically starts with the number 3, followed by your regional water company code and a series of digits. You need your SPID if you want to switch water retailer, query a bill, validate charges, or confirm which premises a bill relates to—especially important if you manage multiple sites or receive combined invoices.
Without the correct SPID, suppliers can’t reliably trace your supply or verify that charges are being applied to the right location. Supplier specific billing explanations below.
Where do I find the SPID on my bill?
We have highlighted the location of the SPID number within these documents.
WaterPlus Customers:
Clear Business Customers:
Castle Water Customers:
Business Stream Customers:
Wave Utilities Customers:
Frequently Asked Questions (FAQ)
❓ How do I calculate my business water bill?
To calculate your business water bill, you need to know whether your premises is metered, how much water is used, and what sewerage charges apply. Metered businesses are charged based on cubic metres of water used plus standing charges, while unmetered businesses are billed using fixed charges linked to rateable value. A water bill calculator uses this information to estimate total costs.
❓ Is this water bill calculator suitable for UK businesses?
Yes. This water bill calculator is designed for UK non-household customers and reflects how commercial water and sewerage charges are calculated in England and Wales. It is suitable for small businesses, commercial properties and larger non-domestic sites, subject to the information entered.
❓ Does the calculator work for metered and unmetered water supplies?
Yes. The calculator is designed to estimate costs for both metered and unmetered business water supplies. Metered bills are based on usage in cubic metres, while unmetered bills are estimated using standing charges and rateable value–based charging methods.
❓ What charges are included in a business water bill?
A business water bill can include water supply charges, sewerage charges, standing charges, surface water drainage, highway drainage and, where applicable, trade effluent charges. The exact charges depend on your supplier, tariff and the type of wastewater your business produces.
❓ Can I use this tool to estimate average water costs for my business?
Yes. You can use this calculator and guide to estimate the average water bill for a small business or commercial property by entering typical usage and known charges. This is useful for budgeting, checking supplier bills, and understanding whether switching water retailers could reduce costs.