We specialise in the design of underground private drainage systems for new developments, meeting the requirements of Part H of the Building Regulations, ‘Drainage and Waste Disposal’.  We consider all aspects that might affect the design such as site topography and levels, building layout and the final point of connection into the public sewer.

We can liaise with the sewerage authority for the submission of capacity check enquiries, S106 applications (for connection of the development to the existing public sewer network) and S185 applications for a sewer diversion (where an existing sewer affects your development and requires diverting).

We pride ourselves on providing clear construction drawings and specifications to ensure there is no uncertainty when it comes to the construction on site.

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


We need to assess the drawings or other information you may have before we can tell you how much our fees would be for any particular project.  You will find our fees highly competitive, often considerably less than those charged by medium and large consultancies.

The list below is a guide to the most frequent drainage engineering services that we provide:

  1. Drainage design for a new build property
  2. S185 sewer diversion
  3. Soakaways and permeable paving
  4. Private sewage treatment system 
  1. Drainage Design For a New Build Property 

This will typically include the design of foul and surface water drainage (including both gravity and pumped systems), provision of construction drawings and a Section 106 application for connection to the public sewer.  Our typical fees range from £450 to £850 plus VAT per property.

  1. S185 Sewer Diversion 

An increasing number of clients wishing to either extend their property, redevelop an existing site or construct a new property are affected by ‘The Water Industry (Schemes for Adoption of Private Sewers) Regulations 2011 which became law on 1 October 2011.  This resulted in the transfer of responsibility for private sewers to the various sewerage undertakers.  If a sewer affects your development, it may need to be diverted as a result of this legislation.  The approval of the sewerage undertaker will need to be obtained before any diversion works can be undertaken, via the submission of a formal S185 Sewer Diversion application.  Our typical fees for the preparation of a S185 Sewer Diversion application range from £625 to £1,000 plus VAT.

  1. Soakaways and Permeable Paving

Soakaways and permeable paving are a means of disposing surface water from roofs and paved areas, where it is not possible to achieve a connection to a public sewer and where there is suitable geology.   Our typical fee for undertaking the design for either system, including calculations and construction drawings is £300 to £450 plus VAT per property.   

  1. 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.  Such systems include packaged sewage treatment plants and septic tanks, which will be dependent on suitable geology for disposal of the arising treated effluent via a shallow ‘field drainage’ type system. Where the geology is unsuitable then we can advise on alternative options including the installation of a sealed cesspit.

Our design will include the provision of calculations, construction drawings and a specification.  Our typical fee for the design of a packaged sewage treatment system serving one property is £550 to £1,000 plus VAT.

The above list is not exhaustive and 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 you.


We do not undertake designs requiring the adoption of sewers via a S104 agreement (Adoption of New Sewerage Systems) with the sewerage undertaker, although we have a list of contacts we can refer you to.


Please contact Glyn on 07804 449935 or email him at glyn@epsdesign.co.uk if you wish to discuss engaging us for any of the above services.