We specialise in the design of underground private drainage systems for individual houses including extensions and small developments. We consider all aspects that affect the design process including topography and site levels, building layout and the means of connecting into the public sewer.

We can prepare applications for 'Capacity Check' enquiries, S106 Sewer Connections, S185 Sewer Diversions on non-critical sewers and 'Build Overs'.  

We provide clear construction drawings and specifications to minimise uncertainties during the construction phase.

If appointed, we will work closely with your Architect to provide a cost-effective solution for your project.


The services that we provide generally fall into the following categories:

1. Private Drainage Design

We undertake the design of private foul and surface water drainage systems for individual houses including extensions and small developments (including both gravity and pumped systems). This usually includes the provision of layout and construction drawings and an accompanying Section 106 Sewer Connection application.

2. S185 Sewer Diversion 

An increasing number of clients wishing to extend or redevelop a site are affected by ‘The Water Industry (Schemes for Adoption of Private Sewers) Regulations.  This transferred the responsibility for private sewers to the sewerage authorities in 2011.  If a sewer crosses your site it may need to be diverted, which requires the approval of the sewerage authority. We specialise in the preparation of S185 Sewer Diversion applications for non-critical sewers and liaise with the sewerage authority to alleviate small developers and householders from the complexity and stress of this process. 

3. Soakaways and Permeable Paving

We specialise in the design of soakaways and permeable paving for disposing of surface water from roofs and paved areas, where the geology is suitable.  We can provide initial feasibility advice through to detailed design, including the provision of calculations required by Building Control and in discharging associated planning conditions

4. Private Sewage Treatment System

Where public sewers are unavailable we can advise on feasibility and undertake the design of alternative systems for draining your development, including packaged sewage treatment plants and septic tanks. This is subject to there being suitable geology for disposal of the arising treated effluent via a shallow ‘field drainage’ type system.  Where the geology is unsuitable we can advise on alternative options including the installation of a sealed cesspit.

We provide calculations, construction drawings and all the information required by Building Control. 

The above list is not exhaustive so if you need advice on any other aspect of drainage design then please contact us as we may have the relevant knowledge and expertise to assist and advise you.


We do not currently undertake designs requiring S104 Sewer Adoption agreements.


For queries or to appoint us please contact us
by phone: 01233 224986  
or by email: contact@epsdesign.co.uk