Flood risk across Wiltshire
Wiltshire has two River Avons: the Bristol Avon through Malmesbury, Chippenham and Bradford-on-Avon, and the Salisbury Avon, which meets the Nadder, Wylye and Bourne at Salisbury. River flooding is the main risk along both, and the chalk of Salisbury Plain and the Marlborough Downs makes groundwater flooding a risk after wet winters.
Flood zones only show river and sea flooding, and they ignore flood defences. Surface water and reservoir risk aren’t part of the zones – check them on the Environment Agency’s long-term flood risk service, or get the full report, which covers every source.
Rivers that shape local flood risk
Main rivers are managed by the Environment Agency. Smaller watercourses and drainage are the responsibility of Wiltshire Council and landowners.
Bristol Avon – Malmesbury, Chippenham and Bradford-on-Avon
Salisbury Avon – Amesbury and Salisbury
River Nadder and River Wylye – Meet the Avon at Salisbury
River Kennet – Marlborough
River Biss – Trowbridge
River Ray – Swindon
Who manages flood risk here
Wiltshire Council and Swindon Borough Council are the Lead Local Flood Authorities, responsible for surface water, groundwater and ordinary watercourses. The Environment Agency manages main rivers and the sea, and issues flood warnings. The same councils also decide planning applications – and asks for a flood risk assessment in Flood Zones 2 and 3.
Getting a written answer for an address
The free check describes the area around your postcode. For a specific property, the full report checks your exact address against every flood dataset and gives you a dated PDF to share with your surveyor, conveyancer or insurer.
For planning decisions, your local council has the final say.
