Business water in the Thames Water area

CCW describes Thames Water’s area as London and the Thames Valley. Parts of that area get their water from a water-only company instead. Affinity covers North and West London and the surrounding Home Counties, and SES covers Surrey, Kent and South London. Sites there typically pay Thames for sewerage and another company for water.

The reverse happens too. Thames notes that some of its water customers get sewerage from Anglian Water, Severn Trent or Wessex Water.

On Water Plus averages, Thames water charges rose 10.6%, sewerage fell 4.9% and trade effluent fell 4.6%. Thames’s own figures show typical increases for business customers buying water only:

• 10.5% on unmeasured supplies
• 10.7% on metered supplies

Wastewater fell 4.9%. For sites taking both water and sewerage from Thames, that adds up to a 4.1% increase.

Thames has also started moving businesses on its intermediate tariff, those using 20,000 to 50,000 m³ a year, onto its standard tariff. In 2026/27, 20% of their discount is being phased out. Thames says this adds at most 1.1% to water charges, or 0.7% for sites taking both water and sewerage. Its September 2025 indicative charges paper gave provisional figures that the January 2026 documents replaced.

This example is illustrative. A café in Reading pays £3,000 a year in wholesale charges, split evenly between water and sewerage. At the typical rates, its water charge would go up by about £160 and its sewerage charge would go down by about £74. That’s a net rise of about £86, or roughly 2.9%, which is below Thames’s typical 4.1% for sites taking both services, so treat it as a rough guide. A similar café in an Affinity area would pay Affinity’s change on water and Thames’s change on sewerage.

If your site isn’t connected to Thames’s surface water sewers, Thames says you may be able to claim back some of your wastewater charges. Under Thames’s 2026/27 tariff document, your retailer applies in writing with evidence, and a site where only some of the surface water is diverted doesn’t qualify. A water audit checks whether you’re owed a drainage rebate and handles the claim.

Thames trade effluent charges fell 4.6% on average for 2026/27. Thames’s 2026/27 tariff document works out charges using the Mogden formula. If your site produces trade effluent, the consent application goes through your retailer.

We’d use your SPID to confirm whether Thames supplies your water, your sewerage or both. Then we’d show the wholesale charge, which is the same whichever retailer you pick, next to retail fees from our panel of licensed retailers. For each one, you’d see the total, the retail fee and the billing basis. You sign by DocuSign, and your supply carries on as normal.

Send us your business address and SPID and we’ll quote straight away. Compare business water suppliers