How to check flood risk on a French house before you offer

By Phil, French House Check. 16 September 2026.

Four sources answer it, and they disagree in ways that matter. The official address report says whether a risk exists, the risk plan says which zone colour the parcel is in, and the map says how far the nearest watercourse is and how far above it the house stands. Read all four before you believe "not in a flood zone".

1. The official address report

Géorisques produces a free risk report for any French address. It lists the risks known for the commune and, where mapped, at the address. The wording needs care: "risque existant" at address level means the address is inside mapped risk zoning, not that it is in a red zone, and "non connu" means the commune has no address-level map, not that there is no risk.

2. The risk plan and its zone

Where a flood risk plan (PPRi) applies, it divides the land into zones, typically red (no new building) and blue (building with conditions). The zone colour at the parcel is what binds. It is only visible on the plan's own maps and in the PDF version of the address report. A parcel can sit 27 m outside the regulated envelope and print as "no risk plan at the point", which is true and misleading in equal measure.

3. Distance and height

Two numbers together tell you more than any label: the distance to the nearest mapped watercourse, and the height of the house above its water surface. A house 49 m from a mountain torrent and 21.6 m above it has a slope question, not a flood question. A house 1.6 m above a river, in a region with no flood atlas, has a question nobody has mapped.

4. The history

Every commune's natural disaster orders (arrêtés de catastrophe naturelle) are public. Four orders in forty years, all storm events, is a light record. A run of flood orders in the last decade is not.

What none of this sees

• Flood plans are rewritten. A parcel outside the current envelope can be inside the next one. The prefecture's site lists plans under revision.
• Some regions have a flood atlas that maps frequent floods where no risk plan exists. Others have none, and the register then says "not known".
• Rising groundwater and surface run-off on clay are recorded at commune level only. A tide line in the cellar on the visit is worth more than either.