Guidance on how to demonstrate that sustainable drainage systems (SuDS) guidance has been considered in your planning application.
New national standards for sustainable drainage systems (SuDS)
On 19 June 2025, the government released new national standards for sustainable drainage systems (SuDS).
The National Planning Policy Framework was updated in August 2026. As stated in part F8 in the policy, SuDS are required on all planning applications that have an impact on drainage on or around the development site.
SuDS should now be designed in accordance with the new national standards.
Bristol City Council is the Lead Local Flood Authority (LLFA) and are a statutory consultee on all major developments for surface water. We also advise the Local Planning Authority (LPA) on surface water flood risk and sustainable drainage for non-major applications.
We've produced guidance below that summarises how you can demonstrate that national and local SuDS guidance has been considered appropriately within your planning application.
You can contact flood.data@bristol.gov.uk if you have any queries relating to SuDS matters.
Major and non-major applications
For both major and non-major applications, a SuDS strategy should be submitted that adheres to the national standards for sustainable drainage systems. Reference should be made to the supporting information in our Strategic Flood Risk Assessment (SFRA) Level 1 (available on our planning evidence page) and the drainage discharge zones within the West of England Sustainable Drainage Guide (available on our flood risk and drainage for developers page) where relevant.
A major application is:
- 10 or more dwellings
- residential development on 0.5 hectares or more with an unknown number of dwellings
- development on 1 hectare or more
- development of more than 1,000 square metres of floorspace
- mineral extraction
- waste development
We recommend you use:
- the Major Development Template to ensure your drainage strategy includes the correct information
- seek pre-application advice
A non-major application is:
- development of 1 to 9 dwellings
- non-residential extension of floorspace less than 250 square metres
- alterations that do not increase the size of buildings
- householder development, for example extensions to the existing building or creation of sheds or garages
We'll not provide a response on these applications with respect to sustainable drainage, we may however provide comments on other aspects such as surface water flood risk and flood evacuation plans.
How to demonstrate you've met the new national standards for SuDS
You should clearly set out how you've met each of the National Standards for Sustainable Drainage within your Drainage Strategy.
There are templates available for major and non-major development on the Planning Portal website. These should help you to provide the right information for review.
We've provided Bristol specific advice below relating to each of the 7 standards.
Standard 1: runoff destinations
You must follow the hierarchy set out in section 1.2 of the national standards.
Bristol is not located in an area identified as seriously water stressed as defined by the Environment Agency's Water Stress Areas 2021 classification. This is not reason alone to discount the use of rainwater harvesting for reuse on site. Your application must show how the other circumstances (non-potable water demand and landscape irrigation) can be met.
Where you have not provided infiltration test results, justification why this has not been completed should be provided. If there is poor infiltration on site, we'll accept British Geological Survey (BGS) mapping or borehole logs on site as evidence of poor infiltration and why testing is not required.
Where discharge to an above ground surface water body is proposed, an unrestricted discharge rate may be acceptable if recommended by us. You should contact flood.data@bristol.gov.uk to discuss this.
Bristol Highways
- Where discharge to a surface water sewer or another piped surface water drainage system is proposed, discharge to Bristol's Highways system shall not be permitted.
- Any runoff from private land shall not discharge into the Bristol Highways system or onto the public highways surface.
- Any private drainage under the Bristol Highway will not be accepted.
- Bristol Highways will require evidence that S104 agreement with a registered Water and Sewerage Company has been provided before a S50 License will be granted.
Wessex Water
- If you're proposing to discharge to a Wessex Water sewer, you must provide evidence that you have proactively engaged with Wessex Water and sought to minimise discharge to the sewer.
- You must provide evidence that Wessex Water have approved the discharge rate and location in principle.
- You must also adhere to any other advice provided by Wessex Water in your response.
- Make a pre-planning enquiry on Wessex Water's planning and capacity page.
The approval of a planning application does not infer acceptance of all licences and permits; it is your responsibility to ensure all relevant permits and licences are obtained.
Standard 2: management of everyday rainfall (interception)
If surface water is being discharged from the site, then a plan showing the type and size of SuDS features should be provided. The plan must show what areas drain to each feature. A table should be provided that details each SuDS feature, the area drained to it and how it complies with Standard 2.
Standard 3: management of extreme rainfall and flooding
Bristol sits within the Avon Bristol and North Somerset Streams catchment for peak river flow and peak rainfall climate change allowances.
We have local evidence for surface water discharge zones. These provide principles for discharging surface water in different areas of the city, they should be adhered to where possible. They can be found at pdf Section 2 of the West of England Sustainable Drainage Developer Guide(2.95 MB) .
Where discharge to an above ground surface water body is proposed, an unrestricted discharge rate may be acceptable if proposed by us. You should contact flood.data@bristol.gov.uk to discuss this.
Where infiltration is proposed, you should confirm the infiltration rate. There should be at least 1m between the base of the infiltration feature and the highest recorded groundwater level.
Where runoff is proposed to discharge to a sewer, you must contact Wessex Water to discuss runoff rates and locations through a pre-planning enquiry. You can make the application on Wessex Water's planning and capacity page.
For all development sites, the lowest discharge rate from the 1 in 2 year (50% AEP) greenfield runoff rate, or 3 litres per second per hectare rate, or the allowable discharge rate from Wessex Water must be used.
For brownfield sites a relaxation factor will only be considered if you can prove that the 1 in 2 year (50% AEP) greenfield runoff rate or 3 litres per second per hectare cannot be achieved.
Standard 4: water quality
You should show this standard has been met through a section in your drainage strategy or a standalone document.
The compliance with Standard 4 may be assessed by other consultees within the council outside of our Flood Risk Management Team.
Standard 5: amenity
You should show this standard has been met through a section in your drainage strategy or a standalone document.
Amenity benefits are a part of the SuDS principles and should be incorporated into drainage design.
The compliance with Standard 5 may be assessed by other consultees within the council outside of our Flood Risk Management Team.
Standard 6: biodiversity
You should show this standard has been met through a section in your drainage strategy or a standalone document.
Biodiversity benefits are generally a part of the SuDS principles and should be incorporated into drainage design.
The compliance with Standard 6 may be assessed by other consultees within the council outside of our Flood Risk Management Team.
Standard 7: design of drainage for construction, operation, maintenance, decommissioning and structural integrity
Construction and structural integrity are outside the Flood Risk Management team's remit and will be assessed by others. You should show this standard has been met through a section in your drainage strategy or a standalone document.
A management and maintenance plan should be provided too as part of your drainage strategy or a standalone document.
Standard conditions
If the fundamentals of your drainage strategy have been approved, then a condition may be applied to allow detailed information to be provided at a later date.
Our standard conditions are listed below.
B35A sustainable drainage systems (SuDS)
I059 Wessex Water requirements
You should comply with Wessex Water requirements and advice. Evidence of this should be provided to and accepted by us. Further information can be obtained from www.wessexwater.co.uk.
I030 land drainage consent
If it's proposed to drain the development directly into a watercourse or carry out works within 8m of a watercourse, then consent will be required. This is obtained through Ordinary Watercourse Consent from the Lead Local Flood Authority, consent from the Lower Severn Internal Drainage Board, or a Flood Risk Activity Permit from the Environment Agency.
For further information read our page on carrying out work on a watercourse.