"What flood zone am I in?" is the first question every flood risk conversation starts with — it decides whether your planning application needs a flood risk assessment, whether the sequential test applies, and in some cases whether your development can go ahead at all. This free checker answers it in seconds using the Environment Agency's Flood Zone 2/3 planning dataset.
Check your flood zone by postcode
The interactive checker needs JavaScript enabled. Without it, use the official Flood Map for Planning.
What the flood zones mean
| Zone | Annual probability of flooding | In plain English |
|---|---|---|
| Zone 1 | Less than 0.1% from rivers or the sea | Low probability — most land in England |
| Zone 2 | 0.1%–1% from rivers, or 0.1%–0.5% from the sea | Medium probability |
| Zone 3a | 1% or greater from rivers, or 0.5% or greater from the sea | High probability |
| Zone 3b | Functional floodplain | Land where flood water must flow or be stored — defined in the council's Strategic Flood Risk Assessment |
Two honest caveats about any zone lookup, including ours: the zones ignore flood defences (they show the undefended picture), and the national dataset does not split Zone 3 into 3a and 3b — the functional floodplain comes from your council's SFRA. Zones also say nothing about surface water, which now affects more properties in England than rivers and the sea combined — see the numbers in our flood risk statistics guide.
What your zone means for a planning application
- Zone 1 — an FRA is needed only if the site is over 1 hectare, within 20 m of a main river, or affected by other flood sources such as surface water.
- Zone 2 — a site-specific FRA is required for any development, and the sequential test applies.
- Zone 3 — FRA required; the sequential test applies, and depending on what you are building the exception test may too. Use our flood vulnerability checker to see exactly which rules bite for your development type.
Frequently asked questions
Is Flood Zone 2 bad?
It is a planning trigger, not a prohibition — most development types are appropriate in Zone 2, but you must submit an FRA and show flood risk has been considered. Thousands of homes get planning permission in Zone 2 every year.
Can I build in Flood Zone 3?
Often yes, depending on vulnerability classification: shops and offices are generally acceptable in Zone 3a, new homes need the exception test, and basements or caravan sites should not be permitted. The functional floodplain (3b) is far stricter. The vulnerability checker walks you through it.
Why does my result differ from the official map?
This tool checks the single point of your postcode; the official Flood Map for Planning shows the full extent across your site boundary, and its May 2026 update added surface-water climate extents — covered in our flood map update guide. Always confirm on the official map before submitting.
How Fortress Associates can help
Whatever zone you land in, our automated flood risk assessment service turns it into a planning-ready document in minutes, free — flood zone screening, surface water risk, sequential and exception test support and a SuDS strategy to CIRIA C753, using live Environment Agency data and the EA's March 2025 FRA template, for householder extensions, new dwellings and small schemes across England. See all services or contact us.
Sources & further reading
Need help with a UK planning project?
Fixed-fee daylight & sunlight reports and Building Regulations drawings — delivered in 4–5 working days, no advance payment — plus flood risk assessments, air quality assessments, energy statements and sustainability statements for planning applications across the UK.
Request a free quote