Flood Risk Assessment in Somerset

A flood risk assessment in Somerset has to explain how a site behaves in a county where, by the Environment Agency's figures, 18% of the land lies below average tide level. Rain off Exmoor, the Quantocks, the Blackdowns and the Mendips runs into the Parrett, Tone, Brue, Axe and Yeo; the Bristol Channel holds those rivers back twice a day; and banks, rhynes and pumps keep the moors dry for most of the year. We prepare flood risk assessments, sequential and exception tests and drainage strategies for sites anywhere in the county, for planning applications, purchases and insurance.

Somerset Council decides most applications and reviews their drainage, from Taunton, Yeovil, Frome and Wells to Minehead and Burnham-on-Sea. North Somerset Council covers Clevedon, Portishead and Nailsea; Bath and North East Somerset Council covers Midsomer Norton, Radstock and Keynsham; and Exmoor National Park Authority decides applications inside the park. The Somerset Levels and Moors run through the centre of all of it.

January 2026 was Somerset's second wettest January since records began in 1871, and on 27 January Somerset Council declared a major incident as the moors filled.

For a fixed-fee quote, call 01293 214444 or email enquiries@unda.co.uk with the site address and a short description of the scheme or purchase.

Five rivers and a tide: how water moves through Somerset

Most of central Somerset drains to one outfall. The Tone flows from the Brendon Hills through Wellington and Taunton to join the Parrett at Burrowbridge, and the Parrett, joined by the Yeo and the Isle and fed by the Cary through the King's Sedgemoor Drain, runs out past Bridgwater to the sea. Further north the Brue drains Glastonbury and the moors west of it, and the Axe leaves the Mendips at Wookey Hole and reaches the coast at Uphill. The Somerset Frome flows the other way, north through Frome to join the Bristol Avon at Freshford.

The larger rivers are main rivers, managed and modelled by the Environment Agency's Wessex area, which also issues the flood warnings. Three internal drainage boards look after the rhynes and pumped drains of the lowland, and Somerset Council regulates the other ordinary watercourses. Our live river levels map shows current readings from the Somerset gauges, including the Tone at Taunton and the Parrett on the moors. For more on the two largest rivers, see our pages on the River Parrett and the River Tone.

Checking a Somerset postcode, and what the national data cannot see

Enter a Somerset postcode in the map below to see the river and sea flood zones, surface water extents, reservoir flooding and any warning area nearby. Our flood risk map will screen any other address in England in the same way. The coral line follows the ceremonial county: Somerset Council's area together with North Somerset and Bath and North East Somerset.

Screening runs on national data. It will not show that a rhyne on the boundary is held at a set level by a drainage board pump, that a field drain backs up while the Parrett is high, or that homes at Bathpool, on the edge of Taunton, flooded in January 2026. Those details come from the council and agency records, the district SFRAs and a look at the site, and they decide what the report has to cover.

1968, 2014 and 2026: Somerset's flood record, event by event

Three floods shaped how Somerset manages water today. The oldest is almost sixty years back; the latest is still under review by the council and the Environment Agency.

1. 10 July 1968. A storm stalled over the Mendips overnight and sent the Chew and its tributaries through north-east Somerset, sweeping away the road bridge at Pensford and damaging Keynsham's. Our article on the Great Flood of 1968 sets out what happened and what it still teaches.
2. Winter 2013 to 2014. The Environment Agency estimated that 100 million cubic metres of floodwater covered 65 square kilometres of the Levels and Moors. Roads across the moors stayed under water for weeks, and since then the Agency says more than £250 million has been spent on flood risk in the area, including raising the road between Muchelney and Drayton so the village is not cut off.
3. March 2014. The Somerset Levels and Moors Flood Action Plan was published. It set out dredging the first 8 km of the Tone and Parrett, finished in 2014, enlarging the River Sowy and King's Sedgemoor Drain, and bringing forward a tidal barrier at Bridgwater.
4. 31 January 2015. The Somerset Rivers Authority was launched to fund extra flood work across the county, beyond what its partners already do.
5. 27 January 2026, Storm Chandra. Somerset Council declared a major incident with its resilience partners. Flows in the Parrett and Tone peaked at about 1.2 million cubic metres an hour, 110 flood warnings were in force across the region, and pumps were added at 19 locations. Defences and pumps protected 2,860 properties; homes still flooded in Bathpool and Ilminster.
6. 9 June 2026. The Government announced £50 million for flood resilience in Somerset. The council is drawing up a two-year programme, and its leader described the work as at a very early stage.
7. 22 June 2026. Thunderstorms caused flash flooding in several Somerset towns, according to the Environment Agency's recovery updates.

Our article on flooding on the Somerset Levels explains why the moors flood and what the new money can and cannot change, and our report on Storm Chandra covers the storm itself. The Environment Agency is still reviewing how its pumps and defences performed in 2026, and Somerset Council is leading a report on the Levels and Moors flooding. Where a Section 19 investigation identifies a street, an assessment for a site on it should deal with what the investigation found.

Taunton and the Tone: the county town's flood scheme

Taunton sits on the Tone, which runs through the town centre between earth banks and walls built after the floods of the 1960s, when more than 360 homes, shops and businesses were affected. Somerset Council's figures put 1,031 properties at risk today, rising to 2,548 by 2118 as flows increase.

The council and the Environment Agency have worked on the Taunton Strategic Flood Alleviation Improvements Scheme since 2014. Its first measures, prioritised in 2020, replace the left-bank defences between Frieze Hill and Town Bridge, raise the lockgates between the canal and the river from Firepool to the Obridge viaduct, and add controlled storage at Longrun Meadow. Together they are meant to reduce the risk to about 1,414 properties, from North Town and Firepool to Priorswood, Bathpool and the Crown Industrial Estate.

Two points matter for a Taunton site. Land behind the works stays in its flood zone, so the assessment still covers residual risk. And because the whole Tone catchment is held to 2 litres a second per hectare in Somerset's drainage standards, new development from Wellington to North Curry has a tighter runoff limit than almost anywhere else in the county.

Yeovil, Frome, Wells and Glastonbury: where small streams and drains cause the trouble

Away from the moors, most recorded flooding comes from surface water and small watercourses. A study funded by the Somerset Rivers Authority picked out Yeovil town centre, Horsey Lane, Millbrook, Pen Mill Trading Estate, the Milford valley, Westfield and the Lynx Trading Estate as priority areas for retrofitting sustainable drainage, and its findings feed a surface water management plan for the town.

In Frome, the town council's river strategy identifies Wallbridge as the part of town most at risk when the Frome is high, with homes, businesses and roads exposed; the town-centre channel was engineered in the early 1980s to stop the centre flooding. Glastonbury and Street sit beside the Brue, with the Glastonbury Millstream carrying a flood warning area of its own, and Wells and Shepton Mallet sit below the Mendip slopes, which shed heavy rain quickly.

South Somerset had its own share in January 2026. Five homes flooded in Ilminster and seven park homes there were evacuated, and the Somerset Rivers Authority held community sessions in Crewkerne and Ilminster afterwards. An assessment in these towns gives as much weight to the surface water map, the drains and any culvert under the site as to the nearest river.

The Bristol Channel coast, from Minehead to Portishead

Somerset's coast faces one of the largest tidal ranges in the world, and two shoreline management plans divide it. The North Devon and Somerset plan runs from Hartland Point to Anchor Head, covering Minehead, the Parrett estuary and Steart, and Burnham-on-Sea; the Severn Estuary plan takes over north of Anchor Head, covering Sand Bay, Clevedon and Portishead. Each sets whether a frontage is to be held, realigned or left to change, and an assessment checks the policy for its stretch.

• Minehead. The Environment Agency added 14,500 tonnes of granite rock armour to the sea wall in 2023 and in 2026 is extending it at the Warren with more than 5,000 tonnes over 100 metres, protecting 355 homes and businesses.
• Burnham-on-Sea and Highbridge. The seafront has its own Environment Agency warning area, and the Brue can only discharge through Highbridge Sluice between tides, which is why the Agency watches levels at Hackness Sluice when the river is full.
• Clevedon and Portishead. Portishead Town Council records that the sea wall was breached and the Lake Grounds flooded in 1981 and again in 1990, and that the Avonmouth tide gauge showed about 11 centimetres of sea level rise between 1924 and 2015.
• Nailsea and the North Somerset Levels. Inland from Clevedon the moors are drained by the North Somerset Levels Internal Drainage Board, and North Somerset's Level 1 SFRA puts about a quarter of the district at tidal risk if the defences were not there.

On this coast we prepare flood risk assessments and flood risk due diligence. Each applies the sea level allowance for the lifetime of the development, checks the standard and condition of the defence in front of the site, and sets floor levels and a dry route out above the tidal flood level.

Three councils, a national park and five inherited plans: who decides a Somerset application

Somerset Council has been a single unitary council since 1 April 2023, replacing the county council and the Mendip, Sedgemoor, South Somerset and Somerset West and Taunton district councils. It still decides applications under the plans those districts adopted, until a new Somerset Local Plan covering the whole county outside Exmoor replaces them. North Somerset and Bath and North East Somerset are separate unitaries with their own plans and flood teams.

The new Somerset Local Plan ran its scoping consultation from 19 June to 9 August 2026 and is not expected to be adopted before March 2029. Somerset Council has already published a county-wide Level 1 SFRA for it, listed on its Local Plan evidence page, and plans a Level 2 SFRA to test the sites it proposes. Until then an assessment uses the district SFRA that covers the site and the new county study, and says which. Our page on Somerset Council's flood and drainage requirements sets out the district policies in more detail.

North Somerset's evidence is on its strategic flood risk assessment page. Courts have weighed the sequential test there too: the Yatton judgment treated a failed test as a matter for the planning balance rather than an automatic refusal, and our note on the Yatton appeal explains what that means for applicants.

Somerset's drainage standards: greenfield rates, the Tone limit and no pumps

Somerset Council, as lead local flood authority, is a statutory consultee on surface water for major development and reviews drainage against the Somerset local SuDS design standards it publishes with the Somerset Rivers Authority. They add to the national standards and are stricter than them in several places.

• Runoff rates. Peak runoff in the 1 in 1, 1 in 30 and 1 in 100 year storms must not exceed the greenfield rate for the same storm. The 5 litres a second minimum often allowed elsewhere does not apply.
• The Tone catchment. Runoff is capped at 2 litres a second per hectare in every storm, or the 1 in 1 year greenfield rate if that is lower.
• No pumping. Drainage that relies on a pump is not accepted unless the applicant justifies it and shows how a pump failure would be managed.
• Climate change. The upper end allowance applies across most of the county; inside a drainage board district the central allowance is used and the upper end tested.
• Brownfield sites. Where greenfield rates cannot be met, a justification statement and an agreed betterment are needed.
• Exceedance. Water beyond the design storm must follow routes that keep it away from people and buildings.

On the Levels the drainage boards add a second consent. The Axe Brue, Parrett and North Somerset Levels boards, run together as the Somerset Drainage Boards Consortium, control works that alter flow or add water to their districts, outfalls, and buildings, fences or land raising within 9 metres of their watercourses. Our guides to ordinary watercourse consent and riparian responsibilities explain the process, and the role of internal drainage boards explains why the boards matter at planning stage.

Which Somerset proposals need a flood risk assessment, and who reads it

National policy decides when an assessment is needed, through policy F4 in chapter 18 of the NPPF, and the lead local flood authority decides how the drainage is judged. The table sets the two side by side for common Somerset proposals; our page on national planning policy for flood risk covers the national rules in more depth.

What we prepare for Somerset sites, and why each comes up here

Each report below answers its own question about a Somerset site: does it flood, should it be built on, and where will the rain go. Each row ties the report to something that has happened, or is required, in this county.

• More than one source on most plots. A field near Langport can sit in the Parrett floodplain, beside a rhyne that only drains while the pumps run and over a high water table, and our flood risk assessment weighs each of those and how they combine.
• With the application. Whether the site is in Taunton, Shepton Mallet or Clevedon, a flood risk assessment for planning sets out the flood zone, the climate change allowance, floor levels and a safe way out for the council and the Environment Agency.
• Before exchange. Searches flag homes on the moors, at Bathpool and along Burnham's seafront, and a flood risk survey for property purchase looks at the building, its floor level and the route out, where a search stops at the postcode.
• Where the whole settlement is low. Around Highbridge or on the Levels, few alternative sites are at lower risk, and the sequential and exception test has to show that properly for the council to weigh it.
• Peat, clay and a pumped system. Infiltration rarely works on the moors, so our drainage strategy establishes early where the water will go and what the receiving rhyne or drain can take.
• Greenfield rates on every storm. A surface water drainage strategy for a Somerset scheme has to meet the county's local standards, including the 2 litres a second per hectare ceiling in the Tone catchment and no pumped outfall.
• After permission. Somerset Council, North Somerset and B&NES all attach detailed drainage conditions to consents, and our discharge of drainage conditions work supplies the calculations, maintenance plan and evidence each one asks for.
• Homes that have flooded before. Bathpool and Ilminster both had homes flooded internally in January 2026, and a flood risk assessment for insurance gives an insurer the site's actual levels and history rather than a postcode score.
• Coastal and industrial land. On the Burnham, Clevedon and Portishead frontages we prepare flood risk assessments and flood risk due diligence for buyers and lenders, covering the tide, the defences and the shoreline plan.
• Trading estates beside the Tone. The council's Taunton scheme names Crown Industrial Estate and Firepool among the areas it protects, and business continuity flood planning helps a business there decide what to raise, move or shut down when a warning is issued.
• Main rivers with tidal and pumped controls. The Parrett, Tone, Brue, Axe and Yeo are all main rivers, and where the published outlines stop short, flood modelling gives a site its own levels.
• Severe warnings are issued here. Three severe flood warnings were in force at the peak of Storm Chandra, and a flood warning and evacuation plan sets out when occupants leave and by which route.
• Land promoted for the new plan. Somerset Council is preparing a Level 2 SFRA to test sites for the Local Plan due in 2029, and a flood risk feasibility study shows a promoter early how much of a field can be built on.

Bath, Bridgwater, Weston-super-Mare and the counties around Somerset

Three places inside the coral outline have pages of their own, and Somerset borders five counties with pages of theirs.

• Bath. Bath and North East Somerset Council plans and manages flood risk for the city on the Bristol Avon; see flood risk assessment in Bath.
• Bridgwater. The tidal Parrett and the barrier under construction downstream of the town are covered in flood risk assessment in Bridgwater, and our article on the Bridgwater Tidal Barrier explains the scheme.
• Weston-super-Mare. North Somerset's largest town has its seafront, the Axe mouth and the Weston moors to deal with; see flood risk assessment in Weston-super-Mare.
• Bristol and Gloucestershire. Across the Avon, Bristol covers the city and Avonmouth, and the Severn's lower reaches are in Gloucestershire.
• Wiltshire, Dorset and Devon. The Brue rises close to the Wiltshire border; the Parrett and the Yeo start in Dorset; and the Exe leaves Exmoor for Devon.

You will find the rest of our county and town pages under the areas we cover.

When water reaches a Somerset property: who to call

Who to ring depends on whether the water came from a river, the sea, a drain or a sewer. If anyone is in danger, call 999 first.

Investment across Somerset, North Somerset, Bath and North East Somerset and the neighbouring counties is overseen by the Wessex Regional Flood and Coastal Committee. Extra work beyond the partners' duties is funded by the Somerset Rivers Authority from just over £3 million a year of council tax, and the Environment Agency posts updates on the 2026 recovery on its Somerset flooding page.

Somerset flood risk questions we are asked before a quote

Call 01293 214444 or email enquiries@unda.co.uk to talk through a site anywhere in Somerset. Every report is written by our chartered consultants and signed off by a senior consultant before it goes out, and Unda Consulting Limited is a CIWEM Business Partner.