5.3.1 Compliance

Below ground drainage that complies with the guidance in this chapter will generally be acceptable.

All drainage schemes require the approval of the building control authority. Local sewerage undertakers may impose additional requirements and restrictions. Both should be consulted early, especially where the drainage system is to be adopted under a Section 104 agreement of the Water Industry Act 1991 or Sewerage (Scotland) Act 1968. The system may need to be inspected and tested by the sewerage undertaker, as well as by the local authority, building control authority and NHBC.

Satisfactory outfall disposal is essential where a septic tank or equivalent sewage treatment plant is installed. In England and Wales, Environment Agency consent may be required to discharge effluent from a septic tank or equivalent sewage treatment plant. In Northern Ireland, the NIEA should approve proposals; in Scotland, the local authority and, where appropriate, the river purification authority should approve proposals.

Ground conditions may preclude the use of septic tanks or equivalent sewage treatment plants in some locations. In all cases, NHBC will require evidence of a satisfactory percolation test where infiltration drainage system is being installed.

For surface water discharge into a watercourse, the permission of the Environment Agency is required in England and Wales. A ‘consent to discharge’ is required from the Department of the Environment in Northern Ireland. In Scotland, the local authority and, where appropriate, the river purification authorities should be consulted.

In all cases:

Table 1: Guide to relevant authority

Last updated: 2nd January 2024

Back to top ⇧