Thames Water
If there is a difference between the amount of water you use and the amount of effluent you discharge into the sewer system, for example water used to irrigate plants. Thames Water may grant a wastewater abatement allowance, which takes these differences into consideration. Customers will need to prove that over ten per cent of their metered water usage is not returned to the sewer for treatment and you should contact them on the details above.
Anglian Water
For domestic customers, Anglian Water already allow 10% for water that does not go into the main drainage system, for metered customers, this means that usage shown by your meter readings will be used in full for water charges but only 90% of the usage will be used for waste charges.
If you are a business customer or can demonstrate that less than 90% of your water is returned to the main sewer, you should contact Anglian Water directly to discuss whether a higher allowance is appropriate for you.