Flood Risk Assessment in Devon

A flood risk assessment in Devon has to account for rivers that rise fast off Dartmoor and Exmoor, two coastlines with their own tides and storms, and surface water in towns where Devon County Council has mapped 24 critical drainage areas. Our consultants prepare flood risk assessments in Devon for planning applications, house purchases, lenders and insurers, alongside sequential and exception tests and surface water drainage strategies.

That covers the county from Exmouth, Sidmouth, Budleigh Salterton, Ottery St Mary, Honiton, Axminster and Seaton in the east to Teignmouth, Newton Abbot, Kingsteignton and Bovey Tracey on the Teign, Totnes, Dartmouth, Kingsbridge, Salcombe and Ivybridge in the South Hams, Tavistock and Okehampton on the edge of the moor, Crediton and Cullompton in mid Devon, and Bideford, Northam, Great Torrington, Braunton, Ilfracombe, South Molton and Holsworthy in the north, across the EX, TQ and Devon PL postcode districts. Exeter, Plymouth, Paignton, Dawlish, Tiverton, Barnstaple and Lynmouth each have a page of their own.

On 9 May 2023 a single storm over the Otter valley flooded 126 properties inside, 61 of them in Newton Poppleford, and Devon County Council put the rainfall at between a 1 in 100 and a 1 in 150 year event.

Send us the address and what you plan to build or buy: call 01293 214444 or email enquiries@unda.co.uk.

Which council deals with a flood risk assessment in Devon?

It depends where the site is. Twelve planning authorities decide applications across Devon, Plymouth and Torbay, and three councils act as lead local flood authority, reviewing surface water, groundwater and ordinary watercourses. Devon County Council does that job everywhere outside Plymouth and Torbay, including inside the two national parks, but it does not decide ordinary planning applications.

In September 2026 the Government paused plans to replace Devon's councils with four unitary authorities while it reviews the reorganisation programme, and the May 2027 local elections go ahead on existing boundaries. Until anything changes, applications go to the district, city, park or unitary council in the table, and Devon County Council remains the lead local flood authority outside Plymouth and Torbay. The Devon and Torbay Combined County Authority, set up in 2025, works on transport, skills and the economy and has no role in planning decisions or flood risk.

Moorland rivers, estuaries and town runoff: where Devon's flood risk comes from

Most of Devon drains off two uplands. The Exe, Taw, Barle and Lyn rise on Exmoor; the Dart, Teign, Tavy, Okement, Erme and Avon on Dartmoor; and the Otter, Sid, Axe and Culm come off the Blackdown Hills in the east. Many of these rivers reach a tidal estuary within a few miles of a town, so river and tide often combine, while intense summer storms flood villages from surface water and small streams that have no warning service at all.

The Environment Agency's register lists 112 flood warning areas and 12 alert areas under Devon, and Plymouth and Torbay have warning areas of their own on the Plym, the Barbican waterfront and the Torbay seafronts. Flood monitoring in Devon relies on the river and tide gauges behind them, which feed our live river levels map. The River Exe, River Dart and River Tamar each have a page of their own.

Look up a Devon postcode

Enter a postcode to see river and sea flood zones, surface water risk, reservoir extents and the nearest warning area. Our flood risk map works the same way for any English address. The coral line follows the ceremonial county: Devon County Council's area with Plymouth and Torbay, and Lundy offshore.

The screening shows the national datasets only. It does not show whether a site sits in one of the county council's critical drainage areas, so we check that list separately for every Devon address.

Flooding in Devon: what the county council has investigated since 2020

Devon's best-known floods each have a page of ours: Lynmouth, where 229 mm of rain in 24 hours on 15 and 16 August 1952 killed 34 people and left 420 homeless; Exeter, where the first defences were built in the 1960s and 1970s after floods reached more than 1,000 properties; and Dawlish, where the sea broke through the railway wall in February 2014. Recent flooding in Devon is recorded in the county council's Section 19 investigations, which count the homes and businesses flooded inside:

1. 14 December 2020. Intense rain and a blocked culvert screen flooded seven properties in Harbertonford, a village with recorded flooding in 2000, 2003, 2013 and 2016.
2. 9 May 2023. A storm centred on the lower Otter flooded 126 properties: 61 in Newton Poppleford with its Burrow and Goosemoor areas, 11 in Tipton St John, 9 in Venn Ottery and 8 in Colaton Raleigh.
3. 2 and 3 November 2023. Storm Ciarán flooded 20 properties, seven of them businesses. Ide was worst hit, with its pub and village hall among six buildings flooded, and waves reached two properties at Seaton.
4. 22 to 25 November 2024. Storm Bert flooded 42 properties across the county. More than 127 mm fell at White Barrow on Dartmoor, and a 40 m breach in the old railway embankment by the Stover Canal sent about a million tonnes of water into a clay quarry.
5. 27 to 29 August 2025. A late-summer downpour flooded 32 properties in nine South Hams communities, 15 of them in Modbury, almost all from surface water.
6. 27 January 2026. In Storm Chandra the River Otter at Fenny Bridges reached 2.83 m, its highest level on record, and a severe flood warning was issued for Ottery St Mary.

Several of these floods came from surface water and small streams, not the main rivers, so a Devon assessment looks hard at the slopes and culverts above a site. Our report on Storm Chandra covers the Otter record, and the council lists every report on its flood investigations page.

Is your site in one of Devon's critical drainage areas?

Check before anything else, because a drainage area can bring a flood risk assessment and a tighter drainage standard to a site in Flood Zone 1. Devon County Council lists 24 critical drainage areas (its page says 23), where surface water has to be managed to a higher standard than normal: Ashburton, Axminster, Barnstaple East and South West, Bideford, Bovey Tracey, Cullompton, Culm Garden Village, Dawlish Warren, East the Water, Feniton, Fremington Yelland, Holbeam, Holsworthy, Ilfracombe and Hele, Ivybridge, Kingsbridge, Modbury, Okehampton, Palmers, Tavistock, Totnes Bridgetown and Warlands, and Whimple.

• Greenfield behaviour up to 1 in 10. The county's guidance asks off-site flows in a drainage area to copy greenfield runoff, up to the 1 in 10 year greenfield rate and volume.
• Brownfield is not exempt. A previously developed site still has to show it matches greenfield rates or comes as close as it can.
• A report of its own in Torridge. Torridge District Council asks for a separate critical drainage area surface water management report with applications in Bideford, Holsworthy and its other drainage areas.
• Plymouth and Torbay. Both unitary councils have drainage areas of their own, handled by their own flood teams.

Devon and Cornwall are the only counties where the Environment Agency has notified areas with critical drainage problems, as our explainer on critical drainage areas sets out. The council's planning and development page links to a map of each one.

What makes a Devon site need a flood risk assessment?

National policy F4, in chapter 18 of the August 2026 NPPF, asks for one in Flood Zones 2 and 3, on sites of a hectare or more, and on Flood Zone 1 land shown at risk from any other source, which in Devon often means surface water on a valley side. In practice the triggers we see on Devon sites are:

• Flood Zone 2 or 3. Valley floors on the Exe, Otter, Axe, Teign, Dart, Taw and Torridge, and the low ground round the estuaries; new homes there usually face the sequential test too.
• One hectare or more. Any site of that size, whatever its flood zone, including farm and employment land on the edge of towns.
• A critical drainage area. Any of the 24 on the county council's list, even for a modest scheme.
• Surface water on the national map. Flood Zone 1 land crossed by a mapped surface water flow route, common below steep fields and in narrow combes.
• Estuary and seafront plots. Sites on the Exe, Teign, Dart, Kingsbridge, Taw and Torridge estuaries or the open coast, where tide, surge and waves are tested with sea level rise.
• Inside a national park. Dartmoor and Exmoor apply the same national tests through their own local plans, with Devon County Council still reviewing the drainage.

Policies F5 and F6 set the sequential test and the exception test for sites in the higher flood zones, and our guide to national flood policy explains each one. If you are unsure which applies, send us the address and we will tell you at no cost.

Drainage strategy in Devon: what the county's SuDS guidance asks for

A drainage strategy in Devon is judged against Sustainable Drainage Systems: Guidance for Devon (2023), which the county council applies as lead local flood authority to major development. Since August 2026 national policy F8 also expects schemes to follow the 2025 National Standards for sustainable drainage. The county guidance sets these figures:

Of all these, the groundwater rule does most to a programme. Monitoring has to cover November to May at the least, so a soakaway scheme whose boreholes go in after the winter has started can wait a full year for an answer; our note on groundwater monitoring for planning sets out the timing. Infiltration has to be proved on site by BRE 365 testing, and our ground conditions and soakaway checker and infiltration rate calculator give a first view. Works in an ordinary watercourse need the county's land drainage consent, separate from planning. The full guidance is on the council's SuDS guidance page.

Two coasts, three shoreline plans

Devon's shoreline policy comes from three shoreline management plans, each setting a policy for every stretch of coast now, by mid-century and to 2105: hold the line, managed realignment or no active intervention, as our guide to shoreline management plans explains.

• South coast: SMP16. The Durlston Head to Rame Head plan, in 17 areas, runs from Dorset past Seaton, Sidmouth, Exmouth, the Exe and Teign estuaries, Torbay and the South Hams to Plymouth Sound.
• North coast: SMP18. The Hartland Point to Anchor Head plan, in 11 areas, covers the north Devon coast with Lundy, the Taw-Torridge estuary and Exmoor's cliffs, and continues into Somerset.
• Hartland to the Cornish border: SMP17. The short stretch south of Hartland Point to the Cornish boundary falls in the Rame Head to Hartland Point plan.

On the Devon coast our work is the flood risk assessment, covering tide, surge and wave overtopping with sea level rise, and due diligence for buyers, lenders and businesses. Where a council asks for an erosion or coastal change study as well, that is a separate report we do not prepare.

Reports for Devon sites, by the question each one answers

A flood risk assessment, a sequential or exception test and a drainage strategy answer different questions: is the site safe, should it be built here at all, and where does the rain go. Each report below is written around Devon's rivers, coasts and the council that will read it.

• Every source at once. A plot below a Dartmoor combe can face a stream, a blocked culvert, runoff off the fields and a river together, and our flood risk assessment weighs each source and how they combine.
• For the planning application. Whichever of Devon's twelve planning authorities decides the scheme, a flood risk assessment for planning gives it and the Environment Agency the evidence on flood zones, warning areas and drainage areas.
• Before exchange. Searches flag waterside cottages at Appledore and Instow and valley-floor houses across the county, and a flood risk survey for property purchase explains the risk to a buyer before they commit.
• Testing other sites. New homes on Flood Zone 2 or 3 land by the Otter, Axe or Teign normally need a sequential and exception test that compares reasonably available sites elsewhere.
• The drainage picture. A drainage strategy sets out how foul and surface water leave a site, from a barn conversion on a private system to an urban extension.
• Rain on the site. With 45% or 50% added to rainfall and long-term storage held to 2 l/s/ha or Qbar, a surface water drainage strategy shows Devon County Council the storage, discharge rate and SuDS features that meet its guidance.
• After permission. When a Devon approval comes with a pre-commencement drainage condition, discharge of drainage conditions supplies the detail the council needs before work starts.
• Homes that have flooded. After 126 properties flooded inside in the Otter valley in May 2023, a flood risk assessment for insurance gives a broker or underwriter evidence for the individual building.
• Coastal and estuary property. From Seaton and Sidmouth on the south coast to Ilfracombe and Bideford on the north, flood risk due diligence sets out the tidal risk and shoreline policy for a harbourside business, holiday park or development site before purchase.
• Keeping a business open. Storm Ciarán flooded the pub and village hall at Ide, and half the 32 properties flooded in the South Hams in August 2025 were businesses; a business continuity flood plan prepares a firm for the next event.
• Water in the ground. Devon County Council wants groundwater monitored from November to May before it accepts a soakaway, and a groundwater flood risk assessment looks at rising water where the ground or the records point to it.
• Rivers off the moor. Sites beside the Otter, Axe, Teign or tidal Torridge can need levels the national maps do not give, which flood modelling provides.
• Getting out in time. Devon has 112 Environment Agency warning areas, and a site that depends on a warning sets out its route out in a flood warning and evacuation plan.
• Solar and wind. Devon's clean energy prospectus, published in October 2025, is seeking investment in renewables, and our renewable energy flood risk assessments cover panels, turbines, substations and access tracks on rural land.

Seven Devon places with pages of their own, and the counties next door

These pages go further into each town's rivers, defences and local plan:

• The Exe and its estuary. Exeter, with its flood defence scheme and the estuary at Topsham.
• Plymouth Sound. Plymouth, a unitary council with its own flood team.
• Torbay. Paignton and Torquay, for Paignton, Torquay and Brixham.
• The railway coast. Dawlish, with Dawlish Warren and the sea wall.
• Where the Lowman meets the Exe. Tiverton, in mid Devon.
• The Taw estuary. Barnstaple, north Devon's largest town.
• The East and West Lyn. Lynmouth, inside Exmoor National Park.
• Over the borders. Cornwall lies across the Tamar, Somerset beyond Exmoor and the Blackdowns, and Dorset east of the Axe. Our areas page lists every county and town we write about.

Who to call about flooding in Devon, Plymouth and Torbay

Call 999 if anyone is in danger from floodwater, and 105 if the electricity goes off. Floodline on 0345 988 1188 gives warnings and advice at any hour, and you can sign up for flood warnings by phone, text or email.

Householders whose homes have flooded can ask the county council about its property flood resilience funding scheme, which helps pay for measures that keep water out of a house or limit the damage.

Devon flood risk questions we answer most often

Our chartered consultants write each report and a senior consultant checks and signs it; Unda Consulting Limited is a CIWEM Business Partner. Call 01293 214444 or email enquiries@unda.co.uk.