Sequential Test for Spelthorne Planning Applications

Where flood risk applies in Spelthorne

The Spelthorne Local Plan (adopted March 2026) and its Strategic Flood Risk Assessment set out the borough's flood risk:

• The Thames floodplainBecause of the borough's position on the Thames, a significant area is at risk of flooding. The flood risk area affects the south and west edges of the borough, including large parts of Staines and Shepperton.
• The Colne and the AshParts of the borough are also in the floodplains of the River Colne and its related river system and the River Ash. Formal flood defences are very limited and are found only on parts of the Colne system and the Ash.
• The River Thames SchemeThe council is working with the Environment Agency, Surrey County Council and others on the River Thames Scheme, which would create new flood relief channels through the borough. Proposals near the scheme need to take it into account.
• ReservoirsThe borough contains four large reservoirs, including the Queen Mary, King George VI and Staines reservoirs. Reservoir flood risk is a separate source of risk that our reports check for every site.

What Spelthorne Borough Council will look for

Spelthorne 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 Spelthorne 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. Spelthorne is made up of several towns, including Staines-upon-Thames, Ashford, Sunbury-on-Thames, Shepperton and Stanwell, so a narrower area matching the town served is often more defensible than the whole borough for smaller schemes.
• Assess the council's own sources of sitesthe Spelthorne Local Plan allocations (adopted March 2026), the council's Statement of Housing Land Supply (March 2026) 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.

Spelthorne-specific pitfalls

• A wider functional floodplainSpelthorne defines Flood Zone 3b (functional floodplain) more widely than many councils. It can include roads, car parks and buildings that do not resist floodwater, and uses the 2% annual chance event on the Colne. Check your site against the council's Flood Zone 3b mapping as well as the Environment Agency flood zones.
• Few defencesWith very limited formal defences, most flood risk in the borough is unmanaged. The Sequential Test uses flood zones as if no defences were there in any case.
• Permissions outside the allocationsThe council lists sites with planning permission in its housing land supply statement without site boundaries. Our reports include them where they are on the brownfield register, and you may want to add others you know of.
• HeathrowParts of the borough are affected by Heathrow's noise contours and public safety zones, and by proposals for its expansion. These can rule out some alternative sites for housing, so check decisive alternatives against the Local Plan policies map.

Fixed-fee Sequential Tests for Spelthorne

We have built our Spelthorne Sequential Test on published Environment Agency and Spelthorne Borough Council data. Plot your site on our Spelthorne 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 Spelthorne.

Source: Spelthorne Level 1 Strategic Flood Risk Assessment (2024).

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