In addition to charges for usage and standing charges, you may notice the inclusion of a site area based charge on your bill.

The purpose of this fact sheet is to explain site area charges, how they are calculated and to provide advice on how these could possibly be reduced or removed.

What are site area based charges?

Site area based charging is a way of determining how much a business property should pay for its surface water drainage. In 2003, Ofwat recommended site area based charging as the fairest means of determining surface water drainage. Prior to this, the charges were based on the property’s Rateable Value. Ofwat found that charging by Rateable Value had meant some customers were effectively subsidising others. For example, a small inner city shop with a high Rateable Value could have been paying more for surface water drainage than a large out of town warehouse with a smaller Rateable Value.

Water and sewerage companies are tasked with removing and processing rainwater that falls on properties and flows directly or indirectly into the public drainage systems. This is known as surface water drainage. If any rainwater from your property drains directly or indirectly into the public network, you are charged by your company for it removing and processing this.

There is a second element of the charge for highways drainage. This is paid by all customers and goes towards the cost of removing water from the highways. There is no mechanism to have the highways drainage element of your bill reduced or removed.

What if not all surface water drains to the network?

You should only pay surface water drainage charges for the portion of the premises where water drains into public sewers. This means that your retailer should not charge you for areas where there is natural drainage, such as playing fields or if your property has a water course or soakaway.

The larger your site area, the more surface water is likely to drain from it. Therefore, charging by site area better reflects the actual costs imposed on the system by customers. CCW believes that the fairest way to charge consumers for surface water drainage is through a site area based approach, which apportions charges to the size of the area drained.

Site area based charging is more environmentally friendly and can help reduce the risk of flooding as it encourages customers to use more sustainable forms of drainage. It also gives customers an opportunity to control how much they pay.

Those who choose to install soakaways to channel rainwater away from public drains, and lay permeable surfaces for car parks and walkways, could, in most cases, reduce surface water drainage charges.

How are Site Area charges calculated?

Surface water charges based on site area fall within a site area banding. Your retailer should calculate your site area charging banding using a number of information sources. This could include digital mapping systems or publically available ordnance survey maps.

To determine your chargeable area, they:

  • Measure the total site area of your premises.
  • Review the site to determine whether or not the surface area is permeable (an area that holds water, and evaporates naturally).
  • Take into account all land from the site boundary and all land held within the boundary.
  • Remove any permanently grassed, cultivated or landscaped areas, where no surface water or ground water drains into a public sewer from their assessment.

A site area charging band is assigned to your premises. This determines how much you should pay for your surface water drainage charges.

Your highway drainage charge is calculated using the boundary of your premises. Once the total area has been calculated you will be assigned a banding based on the total area of your site.

Can site area charges be reduced or cancelled?

Yes. If none of the surface water from your premises enters a public sewer then you may be eligible for the surface water charges to be cancelled.

You may feel that your site area charge has been incorrectly calculated, and therefore you should be in a different banding. Your retailer may not have conducted a recent survey of your site area or may have not taken account of the site area where natural drainage occurs. Alternatively, you may have made changes to the site since it was last calculated, so less water now drains to the network. In these cases, you may be able to have your site area charges reduced, by being put into a lower banding.

Retailers do not know the particular arrangement for surface water drainage of each individual premises in its area. You need to make an application for a reduction in banding or cancellation of charges.

Apply to your retailer, providing evidence that none – or only a portion of – your surface water enters the public sewer. Your company should explain the evidence that it would need to see to assess your request. Typically, this will include a diagram of your site documenting:

  • your property boundary;
  • the public sewer and your connection to it (if known);
  • how the surface water drains from you property, for example the location of downpipes, soakaways, inspection chambers etc. and
  • areas where water soaks into the ground.

Your full site area plan should indicate manhole locations, direction of flows and location of discharge points for both foul and surface water systems. Once your retailer has received your completed form they will arrange for someone to inspect the property to confirm your drainage arrangements. It will let you know the outcome of this.

Retailers tend to reduce or remove charges for the year the application was made and apply this to future bills. Typically, they will not apply the reduction or rebate to previous years.