Change of use, not entailing an increase in drainage surface area

Network impact

In situations where the development involves a change of use but does not lead to an increase of the drained impermeable area that is connected to the public sewer, the risk to the receiving network is unchanged. However; if the receiving network is already exposed to significant operational risk, whether by property flooding or environmental impact from storm overflows, Anglian Water will use opportunities presented by new development to reduce exposure to risk in the existing sewer network.

As such, we expect new development to exploit all reasonably practicable opportunities to reduce surface water flow to the sewer network, in terms of either volume or discharge flow rate. Our aim will be to obtain the maximum achievable benefit without introducing a need to pump flow. Refer to Section 1.5 Surface water pumping stations.

Process

Anglian Water needs to ensure the surface water hierarchy has been followed. We require you to liaise with the relevant LLFA as they are the Statutory Consultee for all surface water drainage strategies on major development sites and are required by law to advise on the broader area drainage constraints.

LLFA approval is an essential pre-requisite to Anglian Water accepting a SW drainage strategy. In the absence of an agreed SW drainage strategy Anglian Water would seek, through planning condition, to ensure surface water is restricted to the discharge rate advised in our policy.

Please note that we will require evidence to demonstrate discussions with the LLFA have taken place and that the drainage strategy has been approved by them.

The SW strategy must clearly identify existing SW drainage arrangements, so that the extent of change in the SW discharge can be reasonably quantified and to ensure there will be a reduction in the volume and / or rate of flow to the sewer network during critical operating phases.

Environmental Incentive

If the approved SW drainage arrangement can be shown to have a net positive environmental impact, you may be eligible to receive an environmental incentive of up to 50% of the wastewater infrastructure charge for the development. More information on the environmental incentive is available on our website.

Network Reinforcement

Not required as no increase in flow.

Alternative disposal options

Other drainage infrastructure
There may be highway drainage within the vicinity of your development that could accommodate the additional flow. Subject to agreement with the Highway Authority, a connection for surface water may be made under the provisions of Section 115 of the Water Industry Act,

New drainage infrastructure and outfall
A new surface water sewer constructed to convey your surface water to a watercourse or as part of a SuDS scheme, where appropriate. Subject to the sewer being designed in accordance with the current version of Sewerage Sector Guidance, the sewer can be put forward for adoption by Anglian Water under Section 104 of the Water Industry Act 1991.
If the outfall is to a watercourse, the applicant may be required to obtain consent to discharge via the appropriate body in addition to approval of the drainage strategy from LPA. The applicant will also need to secure a Deed of Grant of Easement, in Anglian Water’s favour for the right to convey water into the watercourse in perpetuity from the riparian land owner, prior to a sewer requisition.

Installation of offsite sewers

If your site has no means of drainage without crossing third party land then you may be able to requisition Anglian Water, under Section 98 of the Water Industry Act 1991, to provide a connection to the public sewer or an approved outfall for domestic drainage purposes. Guidance on sewer requisition under Section 98 is provided here.

Alternatively, you may wish to enter into a works agreement in accordance with Section 30 of the Anglian Water Authority Act 1977. This will allow you to design and construct the public sewer using Anglian Waters’ statutory powers in accordance with Section 159/168 of the Water Industry Act 1991.

If the outfall is to a watercourse, the applicant may be required to obtain consent to discharge via the appropriate body in addition to approval of the drainage strategy from LPA. The applicant will also need to secure a Deed of Grant of Easement, in Anglian Water’s favour for the right to convey water into the watercourse in perpetuity from the riparian land owner, prior to a sewer requisition.

Sewer adoption

A new surface water sewer can be used as a mechanism to discharge surface water to a watercourse or as part of a SuDS scheme where appropriate. SuDS are classed as sewers; therefore, subject to them being designed in accordance with the DCG Sewerage Sector Guidance, the sewer can be put forward for adoption by Anglian Water under Section 104 of the Water Industry Act 1991.

A pre-design consultation service is available if you would like to further advice on the adoptable standards for SuDS features. Further information can be found here.