Site Area Data: How your surface water and highway drainage charges are calculated

Part of your bill pays for your water company to take away all the rainwater that falls onto your premises, as well as public roads and pavements. This service is shown on your bill as ‘surface water and highway drainage’.

As a non-household customer, the amount you pay for this service is directly related to the chargeable area of your premises that drains to the public sewer. This is often referred to as ‘site area charging’.

To determine your chargeable area, your water company measures the total site area of your premises (whether or not the surface area is permeable) including the boundary and all land held within the boundary, and then exclude any permanently grassed, cultivated or landscaped areas, where no surface water or ground water drains into a public sewer.

The size of your chargeable area determines how much you pay for your surface water drainage and highway drainage services.