Flood Risk Planning Policy Explained in Plain English

‘Flood Risk’ sounds dangerous. Two words suggesting disaster and uncertainty might be enough to put off all but the most seasoned designers and developers. 

In fact, much of what you need to know about developments in areas at risk of flooding can be found in a simple table within the Technical Guidance to the National Planning Policy Framework.

The key policy information is in Table 3 of the NPPF Technical Guidance, which compares flood zones 1, 2, 3a and 3b to 5 different classes of flood ‘vulnerability’, namely ‘more’, ‘less’ and ‘highly vulnerable’, ‘essential infrastructure’ and ‘water compatible’ uses.

Comparing flood risk to flood vulnerability gives a simple yes/no/maybe answer, whereby a ‘maybe’ means a detailed ‘exception test’ is needed. An exception test involves a qualified Flood Risk Assessor arguing for or against a development proposal in both planning policy theory and real-life practical terms. The table below is based on Table 3 but we've changed the wording and the order of the columns to make it a little more accessible. We recommend you check the original source via the Department for Communities and Local Government. The policy quoted from the NPPF replaces the now defunct ‘PPS25 Development and Flood Risk’.

	Highly vulnerable	More vulnerable	Less vulnerable	Water compatible	Essential infrastructure
Zone 1	yes	yes	yes	yes	yes
Zone 2	maybe	yes	yes	yes	yes
Zone 3a	no	maybe	yes	yes	maybe
Zone 3b	no	no	no	yes	maybe

So, you might ask, how do I know how vulnerable my proposal is or what flood zone my site is? Well, most uses are covered in Table 2 of the NPPF Technical Guidance, which we've reproduced below. This table was correct at the time of writing and while we're not expecting it to change any time soon, you can check the original here, if in any doubt.

Essential infrastructure

1. Essential transport infrastructure (including mass evacuation routes) which has to cross the area at risk.
2. Essential utility infrastructure which has to be located in a flood risk area for operational reasons, including electricity generating power stations and grid and primary substations; and water treatment works that need to remain operational in times of flood.
3. Wind turbines.

Highly vulnerable

1. Police stations, ambulance stations and fire stations and command centres and telecommunications installations required to be operational during flooding.
2. Emergency dispersal points.
3. Basement dwellings.
4. Caravans, mobile homes and park homes intended for permanent residential use3.
5. Installations requiring hazardous substances consent4. (Where there is a demonstrable need to locate such installations for bulk storage of materials with port or other similar facilities, or such installations with energy infrastructure or carbon capture and storage installations, that require coastal or water-side locations, or need to be located in other high flood risk areas, in these instances the facilities should be classified as “essential infrastructure”)

More vulnerable

1. Hospitals.
2. Residential institutions such as residential care homes, children’s homes, social services homes, prisons and hostels.
3. Buildings used for dwelling houses, student halls of residence, drinking establishments, nightclubs and hotels.
4. Non–residential uses for health services, nurseries and educational establishments.
5. Landfill and sites used for waste management facilities for hazardous waste6.
6. Sites used for holiday or short-let caravans and camping, subject to a specific warning and evacuation plan.

Less vulnerable

1. Police, ambulance and fire stations which are not required to be operational during flooding.
2. Buildings used for shops, financial, professional and other services,restaurants and cafes, hot food takeaways, offices, general industry, storage and distribution, non–residential institutions not included in “more vulnerable”, and assembly and leisure.
   Land and buildings used for agriculture and forestry.
   Waste treatment (except landfill and hazardous waste facilities).
   Minerals working and processing (except for sand and gravel working).
   Water treatment works which do not need to remain operational during times of flood.
   Sewage treatment works (if adequate measures to control pollution and manage sewage during flooding events are in place).

Water-compatible development

1. Flood control infrastructure.
2. Water transmission infrastructure and pumping stations.
3. Sewage transmission infrastructure and pumping stations.
4. Sand and gravel working.
5. Docks, marinas and wharves.
6. Navigation facilities.
7. Ministry of Defence defence installations.
8. Ship building, repairing and dismantling, dockside fish processing and refrigeration and compatible activities requiring a waterside location.
9. Water-based recreation (excluding sleeping accommodation).
10. Lifeguard and coastguard stations.
11. Amenity open space, nature conservation and biodiversity, outdoor sports and recreation and essential facilities such as changing rooms.
12. Essential ancillary sleeping or residential accommodation for staff required by uses in this category, subject to a specific warning and evacuation plan.

As for the site specific flood zone, you can get a rough idea of the flood risk context via the Environment Agency Flood Map. This facility, doesn't offer property-specific advice, but it will at least let you know what flood zone your development site is probably in. If your proposed use vulnerability isn't compatible with the probable flood zone, then you can commission a Flood Risk Assessor to give a detailed report on your development site. Such a Flood Risk Assessment will usually include a topographic survey, which could help guide your development proposals to overcome any flood risk issues.

It's worth bearing in mind that discussions of flood risk can be alarming but the policies in place are actually quite pragmatic. 'Flood zone 1' might sound disastrous, but it actually means there's practically no risk of flooding at all. Even if your development site is at real risk of flooding, retail and office uses can be supported by planning policy and careful design can overcome can prepare your building and its inhabitants for the occasional bit of disruption. For instance, Richmond Riverside, in South West London regularly floods in parts as the tidal Thames creeps over the tow-path. Bar the occasional bicycle stranded at high tide, locals and visitors alike are used to the events and adapt their habits to suit.

Photo credits, many thanks to;

Nieve44 /Luz

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Mcfarlanmo

Chrisbulle

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