Where flood risk applies in Runnymede
The council's Strategic Flood Risk Assessment (January 2018) identifies river flooding from the Thames and its main tributaries as the primary source of flood risk:
- The Thames floodplainThe Thames floodplain is extensive on the eastern side of the borough, where the land is flat and low-lying, and it presents the greatest river flood risk. The urban areas most affected by past floods include parts of Egham Hythe and Chertsey, and much of Thorpe Park floods.
- The Wey and the Addlestone BourneAreas at risk from the Bourne and the River Wey include Woodham, New Haw, Addlestone and Hamm Moor, and New Haw has flooded from the Addlestone Bourne.
- Egham, Egham Hythe and ThorpeThe Hurst Ditch, Meadlake Ditch and the Moat flow south through Egham, Egham Hythe and Thorpe. Where the Hurst Ditch runs alongside the Chertsey Bourne near Thorpe, their combined flood zones cover a larger area, and the ditches can back up when the Thames is high.
- A long flood historyMajor recorded floods occurred in 1898, 1947, 1968, 2003 and in late 2013 to early 2014, when groundwater flooding was also reported in Egham alongside the river flooding.
What Runnymede Borough Council will look for
Runnymede Borough Council applies the national tests in NPPF Chapter 18 and the Planning Practice Guidance, supported by its Strategic Flood Risk Assessment. A Sequential Test submitted with a Runnymede application should normally:
- Confirm the flood zone and vulnerabilityUse the current Environment Agency Flood Map for Planning and the NPPF Annex F vulnerability class for the proposed use.
- Justify the area of searchNational policy says the area of search should reflect the catchment for the type of development and the need it serves. Runnymede is made up of several settlements, including Addlestone, Chertsey, Egham, Englefield Green and Virginia Water, so a narrower area matching the settlement served is often more defensible than the whole borough for smaller schemes.
- Assess the council's own sources of sitesRunnymede's Strategic Land Availability Assessment (interim, May 2026), which includes the Runnymede 2030 Local Plan allocations, and the Brownfield Land Register are the obvious places to start, and omitting them is a common reason for challenge.
- Evidence every discounted siteWhere an alternative is ruled out as unsuitable, too small or not available in a similar timeframe, give the reason and the evidence. Ownership alone is not enough.
- Screen for the Exception TestState whether the Exception Test applies under Annex F Table 3, and if it does, provide it, drawing on the site-specific flood risk assessment.
Runnymede-specific pitfalls
- No formal flood defencesThe SFRA records that the borough has no formal flood defences. Roads and railways such as the M3 and M25 may hold back water but are not flood defences, and the Sequential Test uses flood zones as if no defences were there in any case.
- Dry islandsThe SFRA maps 'dry islands': land in Flood Zone 1 or 2 surrounded by higher-risk land, including several in Egham Hythe and two in Chertsey. A site there can be in a lower zone yet cut off in a flood, which matters for the flood risk assessment and for how alternatives compare.
- GroundwaterGroundwater flooding risk lies mainly in the Thames floodplain over the Thames Gravels, and usually coincides with high river levels. The Sequential Test looks at all sources of flooding, not only the flood zone.
- Local government reorganisationRunnymede Borough Council is due to be replaced by West Surrey Council on 1 April 2027. For an application made around then, check which council will decide it and which plan and evidence apply.
Fixed-fee Sequential Tests for Runnymede
We have built our Runnymede Sequential Test on published Environment Agency and Runnymede Borough Council data. Plot your site on our Runnymede Sequential Test page and we'll deliver a submission-ready report within 24 hours of payment for £300. Exception Tests are £450 within 48 hours.
New to the subject? Start with our general guide: what is a flood risk Sequential Test? We also cover other council areas at the same fixed fee. For wider planning help, see planning consultants in Runnymede.
Source: Runnymede 2030 Strategic Flood Risk Assessment (January 2018).
Sequential Test guides for other council areas
Spelthorne · Oxford · Dover · Medway · Lewes District · Bristol · Manchester · Birmingham · Chelmsford · Gateshead · Tameside · East Riding of Yorkshire · Wigan · York · Plymouth · Lichfield · Hull · Northumberland
Frequently asked questions
Does Runnymede Borough Council require a Sequential Test?
Yes, for most development in Flood Zones 2 and 3, in line with national policy. Some minor development and most changes of use are exempt, and sites allocated in the local plan may not need the test repeated.
What area of search should I use in Runnymede?
National policy says the area of search should reflect the catchment for the type of development and the need it serves. Runnymede is made up of several settlements, including Addlestone, Chertsey, Egham, Englefield Green and Virginia Water, so a narrower area matching the settlement served is often more defensible than the whole borough for smaller schemes. The reason must be explained in the report.
Do flood defences mean I don't need a Sequential Test?
No. Flood zones for the Sequential Test are assessed without defences. Defences are taken into account in the site-specific flood risk assessment and the Exception Test, not the Sequential Test.
How much does a Sequential Test cost in Runnymede?
Our fixed fee for a Runnymede flood risk Sequential Test or alternatives assessment is £300, delivered within 24 hours of payment. An Exception Test is £450, delivered within 48 hours.
This guide is general information for applications in England and is not advice on your specific project. Requirements differ in Wales, Scotland and Northern Ireland, and every council publishes its own local validation list, so always check the detail with your local planning authority.