Flood Risk In Wales: How Natural Resources Wales Maps And Classifies Flooding

Wales uses the same words as England but not the same system. Welsh Flood Zones include the effects of climate change and cover surface water and small watercourses, both of which England's zones leave out. This page explains the Welsh classifications, who is responsible, how to check an address and what flood risk means for planning and insurance in Wales.

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How Is Flood Risk Classified In Wales?

Flood risk in Wales is classified by Natural Resources Wales on two maps: the Flood Risk Assessment Wales map, which shows present-day risk levels with defences counted, and the Flood Map for Planning, which shows Flood Zones used in planning decisions. Natural Resources Wales states that the first map This map has no official status for planning purposes.

The risk levels Natural Resources Wales uses for each source are shown below.

Sea flooding reaches Medium at a lower chance than river flooding does. For reservoirs, Natural Resources Wales gives no risk level: "We do not provide a risk level for flooding from reservoirs. We show the worst-case scenario." The Welsh Flood Zones are explained in the planning section below.

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Who Is Responsible For Flood Risk In Wales?

In Wales, Natural Resources Wales has general supervision and communication of flood and coastal erosion risk management in Wales, with powers to manage flooding from main rivers, reservoirs, and the sea. Local flood risk from surface water, groundwater and ordinary watercourses is managed by the lead local flood authority, which in Wales is the county or county borough council.

Responsibility for each source is set out below.

Natural Resources Wales also runs the flood forecasting and warning service for Wales, and publishes both national flood maps.

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How Do You Check Flood Risk In Wales?

The flood risk of an address in Wales is shown by entering its postcode into the checker on this site. Natural Resources Wales publishes the same information through its own postcode checker and its two maps.

The official services are:

1. Check your flood risk by postcode — Natural Resources Wales's postcode service.
2. Flood Risk Assessment Wales map — present-day risk levels, with defences counted.
3. Flood Map for Planning — Flood Zones for planning, updated in late May and late November each year.
4. Flood warnings — Natural Resources Wales's warning service is free, by text message, phone call and/or email; sign up online or on Floodline 0345 988 1188, and it can issue warnings across much of Wales.

Every level for one Welsh postcode appears together through check the flood risk of any UK postcode.

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How Does Wales's System Compare With The Rest Of The UK?

Wales shares England's risk level names and river thresholds, but its planning Flood Zones work differently: they include climate change, they cover surface water and small watercourses, and they have no 3a and 3b split. Scotland has no Flood Zones at all, and Northern Ireland plans around defined floodplains.

The four systems are compared below.

The closest English equivalent of Welsh Flood Zone 3 is English Flood Zone 3, but the two are not interchangeable: the Welsh zone already includes climate change and also covers surface water, so land can be in Welsh Flood Zone 3 where the English method would show a lower zone. The property counts are not directly comparable either, because each agency defines and counts risk differently. The English system is explained on flood risk in England, the Scottish system on flood risk in Scotland and the Northern Irish system on flood risk in Northern Ireland.

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Which Areas Of Wales Have The Highest Flood Risk?

The towns and cities in Wales with more than a quarter of their homes in a Medium or High flood risk level for rivers or the sea. Surface water risk follows a different pattern, because it is not tied to rivers or coasts.

The Welsh places with the highest share of homes at risk are listed below, with each county's page ranking the towns within it.

1. Baglan flood risk Medium 16.6% of homes at Medium or High no separate surface water figure
2. Bagillt flood risk Medium 13.4% of homes at Medium or High no separate surface water figure
3. Treherbert flood risk High 12.8% of homes at Medium or High no separate surface water figure
4. Treorchy flood risk High 10.8% of homes at Medium or High no separate surface water figure
5. Rhondda flood risk High 9.9% of homes at Medium or High no separate surface water figure
6. Pontyclun flood risk High 9.1% of homes at Medium or High no separate surface water figure
7. Neath flood risk High 8.1% of homes at Medium or High no separate surface water figure
8. Abersychan flood risk High 7.1% of homes at Medium or High no separate surface water figure
9. Dinas Powis flood risk Low 6.7% of homes at Medium or High no separate surface water figure
10. Maesteg flood risk Low 6.3% of homes at Medium or High no separate surface water figure
11. Ammanford flood risk Low 5.5% of homes at Medium or High no separate surface water figure
12. Bangor flood risk High 5.1% of homes at Medium or High no separate surface water figure
13. Blaenavon flood risk Low 5% of homes at Medium or High no separate surface water figure
14. Cwmavon flood risk Low 4.9% of homes at Medium or High no separate surface water figure
15. Denbigh flood risk High 4.8% of homes at Medium or High no separate surface water figure

Counties in Wales

1. flood risk in Cambridgeshire 5 districts ranked · 6% of homes at Medium or High
2. flood risk in Derbyshire 8 districts ranked · 1.1% of homes at Medium or High
3. flood risk in Devon 8 districts ranked · 3.8% of homes at Medium or High
4. flood risk in East Sussex 5 districts ranked · 1.8% of homes at Medium or High
5. flood risk in Essex 12 districts ranked · 1.1% of homes at Medium or High
6. flood risk in Gloucestershire 6 districts ranked · 2.3% of homes at Medium or High
7. flood risk in Hampshire 11 districts ranked · 1.2% of homes at Medium or High
8. flood risk in Hertfordshire 10 districts ranked · 0.9% of homes at Medium or High
9. flood risk in Kent 12 districts ranked · 2.2% of homes at Medium or High
10. flood risk in Lancashire 12 districts ranked · 2.5% of homes at Medium or High

Natural Resources Wales counts 342,436 properties at risk before removing those counted under more than one source, and over 274,000 after.

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What Does Flood Risk Mean For Planning In Wales?

In Wales, flood risk in planning is assessed against Technical Advice Note 15 and the Flood Map for Planning, and applicants provide Flood Consequences Assessments rather than the flood risk assessments used in England. Welsh Flood Zones 2 and 3 include the effects of climate change for rivers, the sea, and surface water and small watercourses.

The Welsh Flood Zones on the Flood Map for Planning are:

Defences are handled through a separate layer. Natural Resources Wales explains that TAN15 Defended Zones act as a screening tool to enable planning authorities to consider development in areas which may otherwise be mapped as Flood Zone 3 / Flood Zone 2. The map is updated in late May and late November each year, so a site's zone can change between two applications.

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What Does Flood Risk Mean For Insurance In Wales?

Flood cover in Wales is part of a standard home insurance policy, and flood risk affects its price and excess. Flood Re covers Wales on the same terms as the rest of the UK, for eligible homes built before 1 January 2009.

Specialist providers for homes that standard insurers will not cover are listed in the BIBA and ABI Flood Insurance Directory, on 0370 950 1790. How premiums, refused cover and previously flooded homes work is explained in flood insurance, and the scheme's rules in Flood Re.

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Sources (Verified 16 Sep 2026)