Flood Risk Assessment in Hastings

At Unda we use years of experience to prepare clear, robust flood risk assessments and drainage strategies for residential and commercial sites across Hastings. A flood risk assessment in Hastings shows your local planning authority and the Environment Agency that a development will stay safe from flooding for its whole lifetime, without increasing flood risk anywhere else.

Hastings is a steep coastal town where flooding comes from several directions at once — rain racing off the sandstone ridges of the High Weald into the culverted streams beneath the town centre and the Old Town, the Combe Haven backing up the low ground at Bulverhythe, and the sea held off the seafront by a line of defences. We assess every source that matters here, then deal directly with Hastings Borough Council, East Sussex County Council as lead local flood authority and the Environment Agency on your behalf. We prepare flood risk assessments in Hastings for planning, property purchase, mortgage and insurance, and BREEAM, alongside sequential and exception tests and surface-water drainage strategies — guiding architects, planning consultants, developers, landowners, home buyers and businesses through to a decision.

For a quote or to talk a site through, contact one of our experienced flood risk consultants on 01293 214444.

Hastings floods from the hills and the sea at the same time: heavy rain pours off the High Weald ridges into Victorian culverts under the town centre, while a high tide locks their outfalls shut at the coast — so an assessment here has to read surface water, tide and groundwater together.

Flood risk assessment in Hastings at a glance

• Three authorities share the job. Hastings Borough Council determines planning and manages the coast, East Sussex County Council is the lead local flood authority for surface water and groundwater, and the Environment Agency covers the main rivers and the sea.
• The town centre sits over a buried stream. The Priory Stream runs culverted beneath Priory Meadow and the town centre, on ground below a high spring tide — it overwhelmed and flooded Alexandra Park and the centre in January 2023.
• Surface water is the most widespread risk. The borough’s Strategic Flood Risk Assessment identifies surface water as the main flood risk, driven by steep catchments and culverted watercourses.
• The west and the seafront are the low ground. Bulverhythe and West Marina lie in the Combe Haven catchment with a combined tidal and fluvial flood warning area, and the 5 km frontage relies on its seawalls and groynes.
• Soakaways cannot be assumed. The Hastings Beds mix sand and Wadhurst Clay with spring lines, so infiltration drainage has to be tested and often monitored rather than taken for granted.

Check flood risk anywhere in Hastings

The borough of Hastings is outlined below. Screen any postcode in the town against Environment Agency data for rivers and sea, surface water and the planning flood zones, with a climate outlook to 2125. It is an indicative first pass, not a substitute for a site-specific assessment.

Where does flood risk come from in Hastings?

Hastings packs an unusual amount of flood risk into a small, steep town. The built-up bowl of the town centre and the Old Town sit at the foot of sandstone ridges that shed rain fast, two of the main valley streams have been buried in culverts beneath the streets, the western edge at Bulverhythe and West Marina lies low against the Combe Haven, and the whole 5 km frontage from the Old Town to St Leonards sits behind sea defences. Most sites here have to deal with more than one source, and working out which one governs a particular plot is the first job of any flood risk assessment.

Surface water flooding

Hastings Borough Council’s Strategic Flood Risk Assessment identifies surface water as the most widespread flood risk across the town, and the geography explains why. The two streams that drain the central valleys — the Priory Stream under the town centre and the Bourne Stream through the Old Town — were culverted in the nineteenth century and now run in buried channels beneath the streets. A culvert has far less spare capacity than an open channel, blocks more easily, and can surcharge in heavy rain, so when intense rainfall meets a partly silted culvert the water comes up through the streets above. On the night of 15–16 January 2023 the Priory Stream culvert was overwhelmed and floodwater spread across Alexandra Park and the town centre; the outfall at Denmark Place had to be pumped and cleared of shingle, and Southern Water subsequently took over maintenance of the culvert. Because Priory Meadow sits below the level of a high spring tide, the outfall is tide-locked at the worst moments, holding water back in the system just when the rain is heaviest. Since the 2025 Planning Practice Guidance update, surface water flooding can require a flood risk assessment even where a site sits in Flood Zone 1, so it now features on a large share of Hastings applications.

Tidal and coastal flooding

The sea is the second defining risk. The developed 5 km frontage of Hastings and St Leonards is held by a system of seawalls and groynes that retain the shingle beach, much of it rebuilt in major works between 1987 and 1991, and the low ground of the Old Town, the seafront and Bulverhythe relies on those defences staying intact. East of the town, around 7 km of sandstone and clay cliffs run past Fairlight to Pett Level under a shoreline policy of no active intervention, left to erode naturally as a Site of Special Scientific Interest. A defended frontage is not a risk-free one: tidal and coastal flooding has to be assessed for the residual risk that a defence is overtopped or breached, and with sea levels projected to keep rising through the century, a seafront scheme has to look honestly at how the site behaves over its whole lifetime. The coast here is managed under the South Foreland to Beachy Head Shoreline Management Plan, which sets the long-term policy frontage by frontage.

River (fluvial) flooding

River flooding concentrates at the western edge of the borough, where the Combe Haven and the Hollington Stream — both designated Main Rivers — drain the Combe Valley to the sea between Hastings and Bexhill. The low-lying ground at West Marina and Bulverhythe lies within the Combe Haven catchment, and the Environment Agency maintains a combined fluvial and tidal flood warning area covering it. Inland, the Old Roar Gill and Harmer’s Stream feed the ponds in Alexandra Park before joining the Priory Stream system, and the Bourne drains the Old Town valley. Sites along these corridors typically fall in Flood Zone 2 or 3 on the Flood Map for Planning and often need hydraulic flood modelling to establish accurate flood levels, because the national mapping is too coarse to resolve a small, steep urban catchment. Where a watercourse runs through or beside a site, the owner usually carries riparian responsibilities for keeping it clear, which the regulators will expect the scheme to respect.

Groundwater flooding

The geology under Hastings is the Hastings Beds — the Ashdown Formation sandstones, the Wadhurst Clay and the Tunbridge Wells Sand — folded into the steep ridge-and-valley landscape of the High Weald. Where permeable sand meets the underlying clay, springs and seepages break out along the valley sides, and the same junctions are prone to landslip. For a developer this has two consequences. First, groundwater flooding is a genuine source on low ground and in basements, and it appears on no national flood map, so it has to be assessed as a distinct source within the flood risk assessment. Second, infiltration drainage works in some places and fails in others, sometimes within the same street: the sand may take water readily while the clay sheds it, so a soakaway cannot be assumed and has to be evidenced with BRE 365 infiltration testing and, where the water table is in question, a season of monitoring.

A history of flooding in Hastings

Dated events are the clearest test of how the ground really behaves, and Hastings has a well-recorded recent history that local planners read closely. A flood risk assessment in Hastings has to treat that history as evidence rather than background colour.

• October 2000 — the wettest autumn in 270 years. The storms that overwhelmed Lewes and Uckfield fell across the whole of East Sussex, and the autumn of 2000 reset how the county records and defends against flooding. You can read the full account in 25 years on: the legacy of the Lewes floods.
• January 2023 — the Priory Stream flood. After heavy rain on 15–16 January, the Priory Stream culvert was overwhelmed and Alexandra Park and the town centre flooded. Pumps were installed at the Denmark Place outfall and shingle cleared from the culvert mouth; Southern Water then took over its maintenance after years of disputed responsibility.
• November 2023 — Storm Ciarán. Intense rain and coastal conditions flooded roads and properties across Hastings and the wider coast; East Sussex Fire & Rescue had dealt with dozens of incidents across the county by early morning, a recent reminder of combined surface-water and coastal risk.
• 2010 and 2024 — the Bourne Stream. The culverted Bourne caused flooding in the Old Town in both years when debris and silt blocked the channel — a textbook illustration of the residual risk a buried watercourse carries.

Hastings floods from the top down and the bottom up at once: rain races off the sandstone ridges into culverts that cannot always cope, while the sea and a high tide hold the outfalls shut at the coast.

Planning and drainage policy in Hastings

A flood risk assessment in Hastings has to satisfy national policy — the National Planning Policy Framework and its Planning Practice Guidance — and the local bodies that apply it. Unusually for a coastal town, three different authorities share the job, so knowing who reviews what is half the battle in getting a clean decision.

• Hastings Borough Council is the planning authority. It determines applications, manages coast protection along the frontage, and sets local flood policy through the Hastings Local Plan — its Policy SC7 requires flood risk to be addressed from all sources, with the Sequential and Exception Tests applied where necessary and a detailed flood risk assessment submitted.
• East Sussex County Council is the Lead Local Flood Authority. It leads on surface water, groundwater and ordinary watercourses such as the Bourne and Old Roar Gill, carries out Section 19 investigations after significant floods, and decides ordinary watercourse consents. It is the statutory consultee on surface water drainage for major development.
• The Environment Agency covers the main rivers and the sea. It is the consultee on tidal and coastal risk along the frontage and on the Combe Haven and Hollington Stream Main Rivers, and the body whose objection you most need to avoid.
• The Strategic Flood Risk Assessment sets the local evidence. The Hastings SFRA maps the flood zones, surface water risk and the Combe Haven catchment, and underpins the Sequential Test on windfall sites; some Flood Zone 1 land falls within a critical drainage area where an assessment is still required.
• Drainage is judged against the SuDS standards. Assumed soakaway rates no longer pass on the Wealden clay; the county expects infiltration to be evidenced, the surface-water hierarchy followed, and runoff held back to greenfield rates with a climate change allowance.

Get the flood risk and drainage evidence right first time and a Hastings application moves; get it wrong and it stalls behind an Environment Agency or Lead Local Flood Authority objection. Our guide to the NPPF requirements sets out what each report has to demonstrate, and the right vulnerability classification often has to be argued where a building changes use.

What kinds of development need a flood risk assessment in Hastings?

The way Hastings is changing puts flood risk at the centre of a lot of applications. Seafront regeneration places new homes and commercial space on the defended, low-lying frontage — sites such as the former bathing pool and the wider West Marina and West St Leonards area sit where seawall maintenance and coastal-change risk have to be designed in. Town-centre and Priory Quarter infill sits over or beside the culverted Priory Stream. To the west, the Combe Valley regeneration opened up by Combe Valley Way (the Bexhill–Hastings link road) brought new business land into the Combe Haven catchment under a flood management strategy agreed with the Environment Agency. Across all of them, the same triggers decide whether an assessment is required.

• Flood Zone 2 or 3. Almost any development in a medium or high probability flood zone needs a site-specific flood risk assessment for planning.
• Sites of one hectare or more in Flood Zone 1. Larger low-risk sites still need an assessment.
• Surface water risk on the Flood Map for Planning. Common in the central valleys, this can trigger an assessment on otherwise low-risk land.
• Major development needing drainage. Ten or more dwellings, sites over a hectare, or 1,000 m² of floorspace will need a surface-water drainage strategy.
• A change to a more vulnerable use. Converting commercial or seafront floorspace to homes raises the vulnerability classification and usually prompts an assessment.

How Unda helps with flood risk in Hastings

Our flood risk consultants know this stretch of the East Sussex coast well. We have prepared flood risk assessments and drainage strategies across the county — on the defended frontage, in the river valleys and on low coastal ground — and we act as the accurate translation layer between your scheme and the Environment Agency, East Sussex County Council and the Hastings Borough Council planning team. We stay involved past the report to answer objections, because a difficult tidal or surface-water site is often won in the follow-up rather than the first submission.

You can read this and other examples in our tidal Flood Zone 3 case study and a property-purchase case study where a precautionary search result was clarified so a sale could proceed. Every report is overseen and signed off by a senior flood risk consultant, and we aim to reply to every quote request within 60 minutes. Hastings sits within East Sussex, part of our wider Sussex coverage.

Flood risk assessments for every situation in Hastings

People come to us for a flood risk assessment in Hastings for many different reasons, and each is a distinct piece of work. A flood risk assessment, a sequential or exception test and a drainage strategy are three separate reports: the first asks whether the site is safe, the second whether the development should be there, and the third where the surface water goes. They often travel together in a planning submission, but they answer different questions.

• Flood risk assessment for planning. The site-specific report submitted with an application to satisfy the NPPF and the Environment Agency.
• Flood risk survey for property purchase. An independent assessment of the actual risk to a home when a conveyancing search flags flooding.
• Flood risk assessment for insurance. Property-level evidence for brokers and underwriters where cover or premiums are in question.
• Flood risk assessment for BREEAM. Structured around BREEAM Pol 03 to support flood and surface-water management credits.
• Sequential and exception tests. The locational justification that steers development to lower-risk land.
• Surface-water drainage strategy (SuDS). How runoff is managed and kept within agreed discharge rates, with discharge of drainage conditions and preliminary drainage design as the later stages.
• Groundwater assessment and flood modelling. A groundwater section sits within the flood risk assessment; hydraulic modelling derives accurate flood levels where national mapping is not enough.

Not sure which you need? Our NPPF guidance sets out the requirements, or speak to one of our flood risk consultants.

Free flood risk tools for Hastings

Before you commission a report, our free tools give you an early read on a site anywhere in Hastings. They use the same open Environment Agency and British Geological Survey data the regulators use, and they are an indicative screening, not a substitute for a site-specific assessment.

• Flood Risk Map. Screen any postcode for rivers and sea, surface water, reservoirs and flood zones, with a climate outlook to 2125.
• Live River Levels Map. Check the latest Environment Agency gauge readings on the Combe Haven and other watercourses near you.
• Geology and Ground Conditions Map. See the mapped Hastings Beds beneath a site for an early view of whether a soakaway is likely to work.
• Drainage Calculators and the BRE 365 Infiltration Rate Calculator. Size and check drainage and convert soakage test results to a design infiltration rate.

Local flood risk management and emergency contacts

Several bodies manage flood risk in Hastings, and it helps to know who does what — whether you are planning a development, reporting a flooded road or preparing for a storm. In a flood emergency that threatens life, always call 999.

You can sign up for free Environment Agency flood warnings for the Combe Haven and Bulverhythe and the coast through the government’s flood warning service, and report flooding from roads, ditches and surface water to East Sussex County Council as Lead Local Flood Authority.

Flood risk assessment in Hastings: frequently asked questions