What is site area?

Part of your water and wastewater bill covers the costs of removing the rainwater which falls on your building’s roof and any hardstanding areas of your premises or site (surface water drainage), and public roads and pavements (highway drainage). This water is carried through our network of sewer pipes to be cleaned at one of our treatment works across the North West before being safely returned to rivers and the sea. If you have a water meter, your charges for surface water and highway drainage are based on the area of your premises.

This is the service we provide to remove and treat the rainwater that falls on your building’s roof and any hardstanding areas of your premises or site and then drains directly or indirectly to the public sewer. We calculate the cost of this service by assessing the chargeable site area of your premises. If the surface water from all or part of your site does not drain directly or indirectly to a public sewer, you may be able to reduce your surface water charges.

All premises that are connected to the public sewer for surface water drainage, or which benefit from a sewerage service, must pay a highway drainage charge. This covers our costs for removing and treating rainwater that falls on public roads and footpaths in the North West. The charge you pay for this service is also based on the chargeable site area of your premises.

The chargeable site area of your premises includes all land and buildings within your boundary, apart from any permanently grassed, planted or landscaped areas (non-chargeable areas), as we don’t charge for these. If a building has other occupiers besides you, each occupier will be responsible for paying a portion of the charges for the roof area of that building.

To make sure we only charge you your share of the cost, we take the total of the floor area for that building and use the calculator shown below to work out the percentage of the roof area you are responsible for. We use the same percentage to decide what percentage of any communal areas, inside or outside the building,you are responsible for. Adding these two figures together gives your chargeable area.

You can find more information and examples here.