Drainage Strategies & SuDS Design in Kent

We prepare drainage strategies, SuDS designs and flood risk assessments for planning applications across Kent, and help discharge drainage conditions once permission is granted. We work for developers, self-builders, architects and homeowners, from single new homes to small developments.

Get a quote or call 020 3835 2633

What Kent County Council expects
Kent County Council is the Lead Local Flood Authority and a statutory consultee on major development. It reviews drainage strategies against its Drainage and Planning Policy Statement and the national SuDS standards. On smaller schemes, the district or borough council, such as Sevenoaks, Tunbridge Wells or Maidstone, usually deals with drainage itself, often through planning conditions. In practice, a good Kent drainage strategy will:
• Follow the drainage hierarchy, using infiltration where the ground allows before any discharge to a watercourse or sewer
• Be backed by infiltration testing to BRE 365
• Limit discharge rates and provide attenuation for extreme storms with an allowance for climate change
• Show where water goes if the system is exceeded, and who will maintain it

National standards
Defra’s National Standards for Sustainable Drainage, published in June 2025, now apply to new development, and drainage strategies are expected to show how each standard has been met. The revised NPPF also expects SuDS on development that could affect drainage. Read our NPPF article →

Ground conditions
Kent’s ground changes quickly. The chalk of the North Downs often suits infiltration, although groundwater Source Protection Zones need care. The Weald Clay and London Clay areas drain poorly, so attenuation is usually needed, and low-lying coastal and marsh areas can have high groundwater and flood risk.

Local area pages
We also cover Sevenoaks and the rest of Kent.

What we provide
• Drainage strategies and SuDS design for planning applications, from single new homes to small developments
• Infiltration testing to BRE 365 and soakaway design
• Flood risk assessments where the site needs one
• Discharging pre-commencement drainage conditions, and responses to the council and the Lead Local Flood Authority
• Water company applications: sewer connections (Section 106), adoption (Section 104), diversions (Section 185) and build-over agreements
• Structural design for the same project, so the drainage and foundations work together

Common questions

Do I need a drainage strategy for a small scheme in Kent?
Usually, yes. Even where Kent County Council doesn’t comment, the district council will normally expect drainage details, or attach a drainage condition to the permission.

Can I use a soakaway?
Often, on the chalk, but only after infiltration testing. On clay, soakaways rarely work, and attenuation with a controlled discharge is usually needed.

Who handles sewer connections in Kent?
Southern Water across most of Kent, and Thames Water in parts of west Kent. We prepare and submit the connection, adoption and build-over applications for you.

12+ years’ experience · £1,000,000 PI insurance

SuDS and drainage design →
Civil engineering services →
New build structural and civil engineering →
Flood risk assessments →
Other areas: London · Sussex · Surrey
Get in touch or call 020 3835 2633