Flood Risk Assessment in Littlehampton

A flood risk assessment in Littlehampton starts with the tide. The town stands on both banks of the River Arun where it meets the sea, and Arun District Council's 2026 flood study maps river and tidal flooding on both banks and along the whole seafront. Our consultants prepare them for planning applications, purchases, mortgage lenders and insurers, together with sequential and exception tests and surface water drainage strategies.

On this page Littlehampton means the civil parish. That takes in the town centre and the east bank from the harbour mouth to beyond the A259 bridge, the seafront and South Terrace, Wick, Toddington and Courtwick to the north, and the west bank, where Rope Walk, Ferry Road and West Beach face the town across the river. All of it is in the BN17 postcode district, in Arun District, with West Sussex County Council as the Lead Local Flood Authority. Rustington, East Preston, Climping and Lyminster are separate parishes outside the outline.

In April 2024 the tide came over the west-bank defences at Rope Walk and flooded about 20 homes to around half a metre. Across the river the east bank wall stands at 3.94 m AOD; the west bank's protection there reaches only about 3.23 m AOD.

To talk through a Littlehampton site, call 01293 214444 or email enquiries@unda.co.uk. A reply comes from one of our experienced flood risk consultants within 60 minutes.

Two banks, two wall heights: the tidal Arun at Littlehampton

The Arun stays tidal far inland, so at Littlehampton the sea sets the flood level more often than the river does; our page on the tidal River Arun follows it up the valley. Between 2013 and 2015 the Environment Agency, working with Arun District Council, West Sussex County Council and Littlehampton Harbour Board, rebuilt the east bank defences from the lighthouse on the promenade to north of the A259 in a £22 million scheme. The contractor's project record gives 2.5 km of new walls, a 1 in 300 (0.33%) standard with 100 years of sea level rise allowed for, and 748 homes and 340 commercial properties protected. A 26 m gap at 47 River Road, left for a developer to close, was piled by the Environment Agency in the winter of 2017 to 2018.

• East bank. An engineered wall at 3.94 m AOD, from the Environment Agency scheme, runs from Arun Parade near the river mouth through the town centre to north of the A259. The Littlehampton East Bank flood warning area covers the tidal land behind it, including Caffyn's Field and the Riverside Industrial Estate.
• West bank. Walls and banks of mixed age and condition: about 3.23 m AOD along Rope Walk, demountable barriers of about 3.6 m AOD between the units added after 2012, and an embankment to the south as low as about 2.26 m AOD in places, with a gap where the wall meets the bank (Section 19 report, 2025).
• The open coast. The Environment Agency manages the shingle at West Beach and Climping Beach by patch and repair. Before April 2024 the Climping defences gave roughly a 1 in 20 to 1 in 50 standard, falling to 1 in 1 at the access gaps. The shoreline management plan holds the line at Littlehampton and chooses managed realignment from Littlehampton west to Poole Place.
• The strategy upstream. The Lower Tidal River Arun Strategy, approved in March 2014, plans 100 years of management from Pallingham Weir to Littlehampton and Ford: urban walls kept and in places improved, with new defences that "won't be needed for many years".

The walls do not take a Littlehampton site out of Flood Zone 3. The Flood Map for Planning shows the land as if the walls were absent, and the assessment then has to work through the residual case: how deep the water would get, how fast it would arrive and how people would leave if a defence were overtopped or breached. Our explainer on residual flood risk sets out the method.

Look up a street from West Beach to Wick

Enter a BN17 postcode below to screen it against Environment Agency data for rivers and the sea, surface water and reservoirs, with the climate outlook to 2125. The coral line is the Littlehampton civil parish, so Wick, Toddington and the west bank sit inside it. It is a first look, not an assessment; our flood risk map gives the same screen for anywhere in England.

Is Littlehampton in a flood zone? Each source and where it reaches

Parts of it are, and the zone is only one of several things to check. Arun's Level 1 Strategic Flood Risk Assessment of March 2026 finds the Arun's flood extents on both banks, tidal extents along the full frontage and surface water "throughout the entirety of Littlehampton", heaviest on the west bank and at the coast. The table sets out where each source reaches.

Two of these are easy to miss on a quick check. The Black Ditch drains Wick and Lyminster towards the Arun and carries its own warnings, so a site in north Littlehampton can lie well away from the tidal river and still need its watercourse examined. And on this coastal plain the water table is close: where it sits within half a metre of the ground, it decides whether a soakaway can work at all.

Flooding in Littlehampton since 1983: the dated record

The public record for Littlehampton is short: two Environment Agency outlines from the 1980s, a summer cloudburst in 2012 and the surge tide of 2024, with the defence works in between.

1. 2 February 1983 and 7 April 1985. The two Littlehampton entries in the Environment Agency's recorded flood outlines, as listed in Arun's 2026 SFRA.
2. 10 to 12 June 2012. A storm put 114 mm into the Bognor Regis gauge in one event. In Littlehampton about 85 properties around South Terrace were affected as surface water overwhelmed the foul and combined sewers, according to the county council flood report.
3. 2013 to 2015. The east bank walls were raised from the river mouth through the town centre.
4. 8 to 9 April 2024. Storm Pierrick followed Storm Kathleen's rain with one of the highest tides of the year, forecast at 6.75 m chart datum and arriving at 7.1 m. Water came over the west bank from just before midnight. Rope Walk flooded to about 1.5 m outside, around 20 homes and 16 businesses took water inside, Rope Walk and Ferry Road were closed, and residents were led out over the river footbridge in the dark, a substation having flooded. Arun District Council opened a rest centre at The Wave.
5. April 2025. West Sussex County Council published its Section 19 investigation. The Environment Agency told the investigators it had no plans for improvement works on the river; 1,000 m³ of shingle was recycled at Climping in May and June 2024.
6. March 2026. Arun published its new Level 1 SFRA, replacing the 2016 study.

Watch the tide as well as the rain. The live river levels map shows the Littlehampton gauge, where the Environment Agency says property flooding is possible above 3.60 m and the highest level on record is 3.76 m (station 1162); the Section 19 report gives 3.776 m AOD at 00:30 on 9 April 2024. Our explainer on tidal and sea flooding covers how surge and spring tides combine.

Arun's rules for building here: policies W DM2 and W DM3

Arun District Council decides planning applications in Littlehampton under the Arun Local Plan 2011 to 2031, adopted on 18 July 2018. A replacement plan to 2041 is being prepared. The council's 2025 to 2028 development scheme timetabled draft policies for consultation in 2026 and adoption for summer 2028; until a new plan is adopted, the 2018 policies are the ones that apply.

• W DM2, flood risk. In an area at risk, development is permitted only where the sequential test is passed, a site-specific assessment shows the scheme safe "including access and egress", wider sustainability benefits are shown, mitigation is identified, "appropriate flood warning and evacuation plans are in place" and drainage allows for storms beyond its design standard. Schemes must also take account of the Lower Tidal River Arun Strategy.
• W DM3, sustainable drainage. SuDS on every scheme, minor or major, with source control such as permeable drives and water butts; up to six months of winter groundwater monitoring; winter infiltration tests to BRE 365; no flooding in a 1 in 30 year storm, and none to homes or roads in a 1 in 100 year storm with 30% added for climate change.
• Arun's checklists. Since October 2025 the council has checked submissions against its designer checklists for outline and full applications, ground investigation, maintenance and verification. A critical item missed at outline stage "will result in an objection". Our guide to the Arun checklists goes through each one.
• SuDS in flood areas. Arun's position statement keeps SuDS out of Flood Zones 2 and 3 and the 0.1% surface water extent unless the whole site lies within them, with exceptions where the only risk is tidal or the defences are evidenced for the lifetime of the scheme.
• The county council. West Sussex County Council, as the Lead Local Flood Authority, is the statutory consultee on surface water for major development.

Nationally, a Littlehampton application is judged against chapter 18 of the August 2026 NPPF. Policy F4 sets when an assessment is needed, F5 and F6 hold the sequential and exception tests, and F8 expects all development to follow the 2025 National Standards for sustainable drainage. Arun's own flood risk planning page asks for the newest data in both tests, and notes that the climate layer the Environment Agency added to its long-term risk data in April 2026, for 2070 to 2125, shows a much larger area at risk than the SFRA's.

Climate allowances need care on a tidal site. The SFRA's Emsworth to Littlehampton coastal model uses an extreme rise of 1.9 m, which the SFRA itself calls "more conservative than necessary for most forms of development". A site assessment picks the climate change allowance that matches the use and how long it will last.

Where Littlehampton is growing, and what each site has to show

The town's largest housing allocation and its growth area both sit on land the river or the sea can reach. The Local Plan directs employment, retail, leisure and office development to the Littlehampton Economic Growth Area, which covers both sides of the harbour, the town centre, the industrial estates and part of the beach front, and allows new marina berthing only where it does no harm to "the integrity of tidal defences".

The West Bank is the largest single test. Policy H SP2b requires the scheme to "provide the West Bank Flood Defence improvements including flood protection works, land raising, new access points, remediation and land assembly" on the stretch of river where the water came over in 2024, so early work on levels and defences decides how much of the land can take homes. Smaller schemes have their own triggers, such as turning a house into flats behind the seafront.

Reports our consultants prepare for the east bank, the West Bank and Wick

Schemes here raise some mix of three questions: is the site safe, should the development be here at all, and where will the rain go. A flood risk assessment, a sequential or exception test and a drainage strategy answer them, and each is a separate report.

• Tide, rain, sewers and groundwater together. Rope Walk flooded from the river, from a breach of the shingle at Climping and from a ditch that could not drain, so a flood risk assessment here weighs every source at once.
• New homes and changes of use. Arun applies W DM2 to any site in a mapped flood area, so schemes on either bank need a flood risk assessment for planning that covers access, egress and evacuation.
• Before exchange on a riverside flat or a Wick house. A flood risk survey for property purchase reads the walls, the 2024 record and the Black Ditch warnings against the building itself.
• Housing in Flood Zone 2 or 3. With both banks in the zone, the sequential and exception test has to be argued with care; Arun's SFRA includes its own sequential test guide.
• SuDS on every scheme. W DM3 reaches minor schemes too, so most Littlehampton applications need a drainage strategy of some form.
• Where the water table is high. A surface water drainage strategy shows whether infiltration works in the raised beach gravels, backed by winter monitoring and BRE 365 tests, or where the water goes when the outfall is tide-locked.
• Conditions on a permission. Arun's full checklist applies to condition applications as well, so discharge of drainage conditions needs its critical items in place before submission.
• Levels for a riverside site. The defence crest differs by about 0.7 m between the banks and the SFRA's 1.9 m coastal scenario is deliberately cautious, so flood modelling gives a site its own breach and overtopping levels.
• Evacuation over the footbridge. W DM2 asks for warning and evacuation plans, and Rope Walk had to be cleared at night in 2024; a flood warning and evacuation plan sets out the route, the triggers and a safe refuge.
• Homes with a flood history. South Terrace in 2012 and Rope Walk in 2024 are both on the public record, and a flood risk assessment for insurance gives an underwriter the property-level picture.
• Chalk under the raised beach gravels. With groundwater within half a metre of the ground across most of Littlehampton, according to Arun's SFRA, a groundwater flood risk assessment matters where floors, basements or soakaways are planned.
• Sewers that flooded in 2012. The foul and combined network around South Terrace was overwhelmed in June 2012, so a foul drainage strategy shows how new flows connect without adding to the problem.
• Harbour and industrial land. Buyers and lenders looking at the harbour, Railway Wharf or the Riverside Industrial Estate use commercial flood due diligence before committing to land behind the east bank wall.
• Businesses on the waterfront. Sixteen businesses on Rope Walk took water inside in 2024; a business continuity flood assessment sets out what a tenant does once a warning is issued.
• The West Bank and other large plots. Where land raising and new defences decide capacity, as on SD4, a flood risk feasibility study comes before the layout.

Who to call about flooding in Littlehampton, from the beach to the drains

In Littlehampton the river walls, the beach, the road drains, the sewers and the planning decision each have a different owner. If life is at risk, call 999.

Floodline warnings come in separate areas for the east bank, Littlehampton Rope Walk and Lyminster and Wick on the Black Ditch. Anyone who owns or manages property near the river or the ditch can sign up to the area that covers it.

Questions people ask about flood risk in Littlehampton and Wick

Our experienced flood risk consultants also cover Arundel, upstream on the same tidal river, Worthing along the coast and the rest of West Sussex, with Arun's council-wide requirements set out on our Arun District Council page and the full list of places in the areas we cover. Unda Consulting Limited is a CIWEM Business Partner; our consultants are chartered, and each report is signed off by a senior consultant before it is issued. Call 01293 214444 or email enquiries@unda.co.uk.