Want to know how we measure your chargeable area?

We calculate your site area charging band using a number of information sources, from digital mapping systems to publically available Ordnance Survey maps.

To determine your chargeable area, we:

• Measure the total site area of your premises.
• We look at whether or not the surface area is permeable (an area that holds water, and evaporates naturally).
• We look at the site boundary and all land held within the boundary.
• We then exclude any permanently grassed, cultivated or landscaped areas, where no surface water or ground water drains into a public sewer.

Site area charging bands

Once your chargeable area is calculated, a site area charging band is assigned to your premises. This determines how much you pay for your surface water drainage charges. Download our charges at a glance leaflet (PDF download) to view the site area charging bands.

Please note: Any area that has a surface water connection to a public sewer, even if it is permanently grassed, cultivated or landscaped will still be chargeable and included in the measurement of the chargeable area. Public highways are excluded from our measurements where they fall within the site boundaries.

Further information

Our efficiency pages contain lots of information and tips on how you can save.

Contact us

If you are unable to access your map, you think we have put your premises in the wrong site area charging band, or have any other questions about your chargeable area, please call us on 0345 072 6072 or fill in our online form, and we’ll get back to you.

Want to know more about our tariffs and charges? For more information see our charges at a glance 2021/2022 (PDF download) or for all tariffs and charges for business customers you can download our full charges scheme for 2021/22 here (PDF download).