Flood Risk Check
Check flood risk for any UK property. See river, surface water, and environmental risk data from our 29M+ property database.
Powered by Homedata API — environmental risk data for 29M+ UK properties
Access flood, noise, and environmental risk data via REST API
Flood Risk FAQ
What flood risk zones exist in the UK?
The Environment Agency categorises flood risk into four types: river (fluvial), surface water (pluvial), coastal (tidal), and groundwater. Each has risk levels from very low to high, based on the probability of flooding in any given year.[1]
Does flood risk affect property value?
Yes — properties in high flood risk zones are typically discounted against comparable low-risk properties. Academic research (LSE, Environment Agency) estimates this at 5–15% in the UK, varying by flood zone and flood history. Flood risk must be disclosed during property sales and can significantly increase buildings insurance premiums.[2]
Can I access flood risk data via API?
Yes — the Homedata API provides flood risk assessment, noise levels, landfill proximity, and environmental scores for any UK property via UPRN. Free tier: 100 calls/month. Get your API key.
What is surface water flooding?
Surface water flooding occurs when heavy rainfall overwhelms the drainage system and water sits on the surface before draining. It is the most common type of urban flooding and can affect properties far from any river.
Do I need to disclose flood risk when selling?
Yes — flood risk is a material fact on the TA6 property information form. Sellers must declare past flooding and known risk. Failure to disclose can result in legal claims after completion.
Can I get a mortgage on a flood-risk property?
In most cases yes, but some lenders restrict lending on Zone 3 properties or require specialist insurance. The Flood Re scheme exists to help with insurance costs for eligible properties built before 2009.
Sources
Further reading
Source: Environment Agency Flood Map for Planning · Last reviewed: May 2026
Integrate into your own product
Free to startExact flood zone classification (Zone 1, 2, 3a, 3b) for river, surface water, coastal, and groundwater flood risk — including annual probability of flooding and whether statutory flood defences are recorded for the property.
Structured as JSON · queryable by UPRN or postcode · ready to embed in any application
Exact measurements
Real values — distances, concentrations, counts — not rounded ratings
29M+ UK properties
Every address queryable by UPRN or postcode
REST API
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Free tier: 100 API calls/month across all endpoints, no credit card required. Paid plans from £29/month for production use. Compare plans →
What is flood risk by postcode?
Flood risk by postcode means looking up how likely it is that a specific property will flood in any given year. The Environment Agency publishes flood zone classifications for England covering four types of flood risk: river and sea flooding, surface water flooding, groundwater flooding, and reservoir flooding. Each type has its own risk band — from very low (less than 0.1% annual chance) to high (greater than 1% annual chance). This tool displays river and surface water risk, which are the two categories most relevant for residential property purchases.
How flood risk data works
The Environment Agency's Flood Map for Planning is built on hydrological modelling of river catchments, coastal tidal data, and surface water drainage capacity. Properties are assessed at grid level and assigned to a flood zone. The zones are:
- Zone 1 — Less than 0.1% annual probability. Most UK properties fall here.
- Zone 2 — 0.1–1% annual probability for river flooding; 0.1–0.5% for coastal.
- Zone 3a — Greater than 1% annual probability. Flood risk assessment required for planning applications.
- Zone 3b (Functional floodplain) — Designed to store or convey floodwater. Residential development not normally permitted.
Surface water risk is mapped separately using drainage modelling — it often affects properties in urban areas that are not near any river.
Why flood risk matters before buying
Properties in flood risk zones carry practical and financial implications. Buildings insurance for a Zone 3 property can cost significantly more than an equivalent Zone 1 property — and some mainstream insurers will not quote at all, directing buyers to specialist providers. The Flood Re scheme helps with insurance for eligible homes built before 2009, but it does not cover all scenarios.
Mortgage lenders increasingly require a formal flood risk assessment for Zone 3 properties. A structural survey may also flag flood evidence — staining, suspended floors, or previous remediation works — that the online tool will not detect.
For developers
Embed flood risk on your site
Drop-in widget with the same Environment Agency data, scoped to your domain, no API key in your JavaScript. Two lines of HTML.