Southwest Environmental Limited
London Bristol Manchester Exeter
02076 920 670 01173 270 092 01612 970 026 01398 331 258
Environmental Consultancy Services to Industry, Business and Individuals

Flood Risk Assessment - What is the Sequential Test?

Southwest Environmental Limited can undertake a Sequential Test for your site / project. Our method meets with near 100% acceptance. We normally include this sequential test as part of our standard Flood Risk Assessment .

Planning Policy Statement 25: Development and Flood Risk (PPS25) sets out national planning guidance in relation to flood risk. PPS25 requires Local Planning Authorities (LPAs) to take a sequential risk-based approach to determine the suitability of land for development when allocating sites in the Local Development Framework (LDF) or determining planning applications.

Through the application of the sequential test, the overarching aim of PPS25 is to steer development to areas at low risk from flooding.

 PPS25 articulates a presumption in favor of locating new development in Flood Zone 1 (low probability). If there are no reasonably available sites in Flood Zone 1, the flood vulnerability of the proposed development can be taken into account in locating development in Flood Zone 2 (medium probability) and then Flood Zone 3 (3a high probability and 3b functional floodplain).

Sequential Test Environmental Consultants

The Sequential Test aims to ensure that development does not take place in areas at high risk of flooding when appropriate areas of lower risk are reasonably available.

Paragraph 19 of PPS25 recognizes the fact that wider sustainable development criteria may require the development of some land that cannot be delivered through the sequential test. In these circumstances, the Exception Test can be applied to some developments depending on their vulnerability classification (Table D.2 of PPS25). The Exception Test provides a method of managing flood risk while still allowing necessary development to occur.

When is the Sequential Test required?

Development proposals within flood risk zones 2, 3a and 3b must have gone through a sequential testing process unless any of the following circumstances apply:

1.If the development is considered to be inappropriate for the flood zone of the site. These circumstances are listed in table C below and more fully in table 3 of the NPPF Technical Guidance. In such circumstances permission would normally be refused and therefore it is not advisable to submit a planning application.

2.The proposal is for the change of use of land/buildings only*.

3.The proposal is a minor non-residential extension only (i.e. less than 250 square metres)

4.The proposal is development that does not increase the size of the building e.g. alterations to external appearance.

5.The proposal is for householder development (extensions and detached buildings etc) provided that the proposal is not associated with the creation of a separate unit of residential accommodation.

6.We, as part of the Local Development Framework (LDF) or Local Plan process, have already sequentially tested the site**.

7.For a replacement building (see the PPS25 Practice Guide, para. 4.40)***.

8.For an ongoing and existing regeneration scheme (see the Practice Guide, para. 4.38). Although in such circumstances a sequential approach to the location of development within the application site may still need to be applied.

* Except for any proposal involving a change of use to a caravan, camping or chalet site, or to a
mobile home or park home site, where the Sequential and Exception Tests should be applied as
appropriate. For any change of use, if significant operational development (physical works) is
proposed then evidence of a Sequential Test is required.

**If the proposed development is not in accordance with the allocations and relevant planning
policies then a Sequential Test will need to be submitted with the application. For example, if
housing is proposed on a site allocated for a less vulnerable industrial use.

*** Where an applicant seeks to redevelop a property, by demolishing an existing building and
erecting a new one, the Sequential Test need not be applied so long as the following criteria are

SWEL have considerable experience in demonstrating the sequential test for small scale planning applications. Our method for the sequential test has met with 100% acceptance with a variety of local planning authorities.

How to Carry Out the Sequential Test

At a national level guidance on how to carry out the sequential test is very wooly / vague / nebulous. However there is some guide guidance available in some areas at a local level, and where this does occur it is a godsend / blessing / bonus.

Without a good set of rule on how to carry out the sequential test you are left at the mercy of whoever is assessing your sequential test report. That could be you local planning authority (LPA) or the Environment Agency (EA). Hopefully not the latter.

The test requires that other sites in the area are checked to see if they are viable alternatives, to the site you are proposing. In reality this is crazy because most of our clients already own the piece of land they are trying to develop, and so to consider alternatives is . . . not realistic.

Thankfully in areas where LPAs have a good set of rules there are a list of criteria, which an alternate site must meet to become a viable alternative. These might include area, planning status, geo-locality and in short this results in most development sites in the area being found to be unsuitable.

If you are looking to undertake this work yourself, it can be done if you have the time. Bristol City Council have the best guidance I know of, perhaps use that if your LPA does not publish its own guidance on sequential testing. However, if you would rather we carry out your sequential test on your behalf then please get in touch.

Please feel free to contact the office for an informal discussion regarding your requirements.


Home > Flood Risk Assessment > What is the Sequential Test?