Wales has separate flood information for planning and for present-day defended risk. For a planning check, start with Natural Resources Wales’ Flood Map for Planning and the current Technical Advice Note 15 (TAN 15) process. A coloured area is a screening result, not a decision that an ADU is suitable or unsuitable.

Use the planning-purpose map

The Flood Map for Planning supports TAN 15 and shows potential flood extents, including climate-change effects over the coming century, assuming no defences. Its Basic view supports high-level planning screening; the Detailed view adds information that may help prepare a Flood Consequences Assessment (FCA). Check the map date and the individual layer’s status. NRW says the map is updated in May and November as information becomes available; its published May 2026 update changed specified river zones and a defended zone at Mold.

The map can help identify whether the site needs further planning assessment, but it does not resolve the parcel, local model coverage, development vulnerability, or condition of a defence. A defended-zone designation is not an automatic finding that development is appropriate; an FCA may need to reassess protection or use hydraulic modelling.

Do not substitute the present-day defended-risk viewer

Flood Risk Assessment Wales shows present-day risk with defences, but NRW says it has no official planning status because it does not account for future climate change. It answers a different question from the planning map. Surface water, small watercourses, and sewer flooding also have separate advice routes: ask the local authority about surface water and small watercourses, and the water company about sewer flooding.

For the proposed site and design, ask the local planning authority which TAN 15 zone and map date apply, whether an FCA is required, what local studies are available, and whether NRW should be consulted. Preserve the layer, view, and date used, and follow current authority instructions if the map and local records differ.

The screen does not establish a parcel’s flood conditions, defence performance, FCA requirement or outcome, or permission to build. See the broader flood, conservation, wetland, and hazard checks for other site-specific inquiries.