Flood Risk Assessment in Lancashire

Our team at Unda use years of experience to prepare comprehensive flood risk assessments and drainage strategies for commercial and residential sites across Lancashire. A flood risk assessment in Lancashire shows your local planning authority that a development will stay safe from flooding for its whole lifetime, without pushing flood risk onto anyone else.

Lancashire runs from the Pennine moors and the Forest of Bowland down to the Fylde coast and Morecambe Bay, drained by the Ribble, the Wyre and the Lune and their tributaries. We assess every source that matters here — the rivers and their tidal lower reaches, the sea along the Fylde and Morecambe coasts, the surface water that overwhelms drains in the towns, and the groundwater that rises through low-lying ground — then deal directly with the Environment Agency and the relevant Lead Local Flood Authority on your behalf. We guide architects, planning consultants, developers, landowners, home buyers and businesses through to a decision, whether the report is needed for planning, a property purchase, mortgage or insurance, BREEAM, or a surface-water drainage strategy.

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

Lancashire floods from three directions at once — rivers draining off the Pennines and Bowland, the tide pushing up the Ribble, Wyre and Lune and against the Fylde and Morecambe coasts, and surface water ponding in the towns — so an assessment that reads only the river map will not stand up to the Lead Local Flood Authority.

Flood risk assessment in Lancashire at a glance

• Three rivers shape the county. The Ribble, Wyre and Lune drain off the Pennines and Bowland, and their lower reaches are tidal — so many sites face river and sea flooding together.
• Around 5,200 homes flooded across Lancashire and Cumbria in Storm Desmond, in December 2015, with Whalley, Croston, Padiham, Ribchester and Parbold among the worst hit — the event that reshaped flood defence investment across the county.
• Three Lead Local Flood Authorities — Lancashire County Council, Blackpool Council and Blackburn with Darwen Council — cover the ceremonial county. We work with all three.
• Flood Zone 1 is not a free pass. Since the 2025 PPG update, surface water risk can trigger an assessment even on a Flood Zone 1 site.

Check flood risk anywhere in Lancashire

Lancashire is outlined below. Screen any postcode in the county 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.

Flood risk in Lancashire: the Ribble, Wyre and Lune, the coast and surface water

No single source dominates in Lancashire. The Ribble, Wyre and Lune drain steep Pennine and Bowland catchments that respond quickly to rain; their lower reaches are tidal, so river flow and high tides can arrive together; the Fylde and Morecambe coasts face the sea directly; and surface water now overwhelms drains in the towns. Most sites here face more than one source at once.

The rivers rise fast. Rain on the uplands around Bowland, Pendle and the West Pennine Moors becomes a flood peak in the valley towns a short time later, which is why Whalley, Padiham, Croston and Ribchester have flooded repeatedly. Where the Ribble, Wyre and Lune meet the sea, a river in spate during a high spring tide has nowhere to discharge, and that combination drives the risk along the lower valleys and the coast. Understanding which source — or which combination — drives the risk on a given site is the heart of a credible fluvial flood risk assessment.

• Rivers (fluvial). The Ribble, Wyre and Lune and their tributaries — the Calder and Hodder in the Ribble Valley, the Darwen and Douglas in the south, the Brun through Burnley — flood the valley floors. Land in Flood Zones 2 and 3 along these corridors almost always needs an FRA.
• Tidal and coastal. The lower Ribble, Wyre and Lune are tidal, and the Fylde coast from Blackpool to Lytham St Annes, plus Morecambe Bay, face flooding from the sea. See tidal (sea) flooding and rising sea levels.
• Surface water (pluvial). Now the most widespread flood risk in England. Intense rain ponds along flow routes through Blackpool, Garstang, Lytham and Kirkham and in the East Lancashire towns. Since the 2025 PPG update, surface water on the Flood Map for Planning can trigger an assessment even on a Flood Zone 1 site.
• Groundwater and low-lying drainage. The West Lancashire mosslands and parts of the Fylde sit low and drain slowly, so water tables rise and pumped or gravity drainage governs the risk — critical for any soakaway or below-ground level. See groundwater flooding.

The Fylde coast is the textbook case for why one map is never enough: a low-lying site can screen clear of the rivers yet face the sea, surface water with nowhere to drain by gravity, and a high water table all at once. A scheme there has to reconcile all of them. Our notes on the sources of flood risk and on surface water and planning set out how these sources interact.

A history of flooding in Lancashire

These dated events are why local authorities here scrutinise development so closely, and why a flood risk assessment in Lancashire has to be evidence-led rather than generic. Each one reshaped local policy and the flood defences a developer now has to design around.

• December 2015 — Storm Desmond. On 5–6 December 2015 record rainfall caused around 5,200 homes to flood across Lancashire and Cumbria, with more than 100 properties flooded at Whalley alone and serious flooding at Croston, Padiham, Ribchester and Parbold. It remains the benchmark flood event for the county.
• Boxing Day 2015 — Storm Eva. Weeks later, rivers across Lancashire peaked at their highest levels since records began, with further evacuations in the Ribble and Calder valleys. A flooded electricity substation at Lancaster left tens of thousands of homes without power, a stark lesson in how flooding cascades into other infrastructure.
• The wider pattern. Storms Ciara and Dennis in February 2020 again hit the Calder valley and East Lancashire, part of a run of repeated flooding that has driven major investment in defences across Preston, the Fylde and the Ribble Valley.
• Why it matters for your site. The Environment Agency now records around 6.3 million properties at flood risk in England, and Lancashire's varied geography — uplands, lowlands, rivers and coast — means recorded local flooding is treated as evidence the regulators expect an assessment to engage with directly.

A pattern runs through all of it: ground that flooded once tends to flood again. A robust assessment treats this recorded history as evidence, not background colour.

Flood defences and schemes protecting Lancashire

Major investment followed the 2015 floods, and the schemes change what a development next to them has to prove. A new defence reduces the chance of flooding, but it never removes it, and planning policy still expects the residual risk to be assessed.

• Preston and South Ribble Flood Risk Management Scheme. The first phase of this Environment Agency scheme — more than £55 million and around two kilometres of new flood defences along Broadgate, Riverside and Lower Penwortham, some glass-topped — was completed in June 2026, better protecting homes and businesses along the tidal Ribble.
• The Fylde coast. Coast protection schemes along the Fylde frontage have invested in the order of £188 million, helping to protect around 23,500 properties at Blackpool, Cleveleys and Rossall against tidal and coastal flooding.
• A system under pressure. Defences have finite capacity, and climate change is loading them harder. Recent UK research on hydroclimatic whiplash singles out Atlantic-facing uplands like Lancashire for the sharpest rises in extreme rainfall.

The catch for developers is the one we set out in residual flood risk and why a site stays in a flood zone after defences are built: the Flood Map for Planning is drawn as if the defences are not there, so a defended site can still sit in Flood Zone 3. Climate change makes this sharper still, which is why an assessment applies the Environment Agency's allowances over the development's lifetime and accounts for increasing rainfall.

Planning policy and your Lead Local Flood Authority in Lancashire

Two kinds of authority set the rules. The Environment Agency leads on the main rivers — the Ribble, Wyre, Lune and their tributaries — and the coast. A Lead Local Flood Authority (LLFA) leads on surface water, groundwater and ordinary watercourses, and Lancashire has three of them.

Across the ceremonial county there are three LLFAs: Lancashire County Council, which covers the twelve districts from Preston to Pendle, and the two unitary authorities of Blackpool and Blackburn with Darwen, each its own LLFA. A developer here deals with whichever authority covers the site, alongside the Environment Agency and the role the LLFA plays as statutory consultee on surface water drainage. Our overview of who manages flood risk in England explains how the pieces fit together.

Your assessment and drainage strategy must satisfy national policy — the NPPF and its Planning Practice Guidance — and the local framework: the Joint Lancashire and Blackpool Local Flood Risk Management Strategy, the relevant Strategic Flood Risk Assessment and adopted Local Plan flood policies. Where a higher-risk site is involved, the Sequential and Exception Tests apply, and the right vulnerability classification has to be argued — a live issue in Lancashire after the High Court Gladman judgment arising from a Lancaster scheme. On drainage, the 2025 national SuDS standards and the four pillars of SuDS shape what each LLFA will accept.

What your flood risk assessment in Lancashire must show

• Risk assessed from every credible source, using the Flood Map for Planning and local data.
• An appropriate location, tested against the Sequential Test where policy requires it.
• Safe for its lifetime, once the climate change allowances are applied.
• No increase in flood risk elsewhere, with attenuation and, where needed, compensatory storage.
• Residual risk managed, with safe access, egress and finished floor levels. Get one of these wrong and the application stalls, as our note on LLFA drainage objections shows.

Development and flood risk assessment in Lancashire

Lancashire is building at pace, and the kind of site you bring forward shapes the assessment you need. The right scope is the difference between a clean approval and a drainage objection that holds an application up for months.

• Central Lancashire growth. The emerging Central Lancashire Local Plan plans more than 25,000 new homes across Preston, South Ribble and Chorley to 2041, many on sites where the Ribble and Darwen floodplains and surface water shape the masterplan.
• Riverside and waterfront regeneration. Regeneration along the tidal Ribble at Preston and Riversway, and along the Lune at Lancaster, frequently sits in Flood Zones 2 and 3, needing finished floor levels, safe access and egress, and often compensatory flood storage.
• Fylde coast development. Housing and tourism schemes along the Blackpool and Fylde frontage have to address tidal and coastal flooding and surface water together, with sea-level rise factored over the lifetime of the scheme.
• Rural and upland schemes. Conversions and new builds across the Ribble Valley, Bowland and West Lancashire often turn on surface water and ordinary watercourses rather than a main river, and on the right drainage information for planning.

Climate change is not optional here. A Lancashire assessment must apply the Environment Agency's allowances for higher river flows, rainfall and sea levels over the development's lifetime — generally 100 years for housing — which sets floor levels, freeboard and how much attenuation a drainage scheme needs.

Home buyers and businesses come to us too. A flood risk question can affect a purchase and house prices, and a conveyancing search is not the same thing as a planning-grade assessment. Knowing which you actually need saves time and money, and our guide on doing your own assessment explains where the line falls.

How Unda helps with flood risk assessment in Lancashire

We act as the accurate translation layer between your scheme and the requirements set by the Environment Agency, the relevant Lancashire LLFA and national planning policy. We are experts on the county's flooding, not a generic report mill.

A flood risk assessment in Lancashire from Unda assesses every credible source — the Ribble, Wyre, Lune and their tributaries, the tide and the coast, surface water, groundwater and any ordinary watercourse on the boundary — compares modelled flood levels against your proposed floor levels, sets safe access and egress, and recommends mitigation the regulators will accept. We are a CIWEM Business Partner with chartered members, and a senior consultant signs off every report. Where the council needs it, a surface-water drainage strategy sits alongside the assessment as a separate report so the two cases stay consistent and an objection has nowhere to land.

Flood risk assessments and related reports for every situation in Lancashire

A flood risk assessment, a Sequential or Exception Test and a drainage strategy are three distinct reports. They often travel together in a planning submission, but they answer different questions: is the site safe, should the development be here, and where does the surface water go. We prepare all three, alongside the right form of assessment for buyers, lenders and BREEAM.

Flood risk assessments

• Flood risk assessment for planning. The core report, site-specific and prepared to satisfy the NPPF, the Environment Agency and your Lancashire LPA. Groundwater and, where needed, flood modelling are assessed within it rather than as separate reports.
• Homebuyer and property-purchase survey. For conveyancing, where a search has flagged Ribble-valley, tidal or surface-water risk and you need the actual building assessed, not a broad map.
• Flood risk assessment for insurance. Property-specific evidence for brokers and underwriters where premiums have risen or cover has been restricted.
• Flood risk assessment for BREEAM. Structured around BREEAM Pol 03, which is credit-driven rather than safety-driven, so a planning FRA alone rarely satisfies it.
• Groundwater flood risk. A defensible design water table for the West Lancashire mosslands, the Fylde and any basement — assessed as a source within the FRA, or as a standalone hydrogeological assessment on complex sites.

Sequential and Exception Tests

The Sequential and Exception Tests are a separate, locational report about whether a development should be in a higher-risk location at all. The Sequential Test defines an area of search, identifies reasonably available lower-risk sites and justifies the proposed site; the Exception Test is the second gate where development still needs to proceed. A clean site-specific assessment showing the development is not actually within an area at risk can remove the need at application stage — a live policy area in Lancashire, as our note on the Gladman judgment from a Lancaster scheme explains.

Drainage strategy and SuDS

• Sustainable drainage strategy (SuDS). Surface-water engineering — calculates existing versus proposed runoff and proposes SuDS to hold discharge within the local standards.
• Preliminary drainage design. The early, outline read that flags infiltration issues before they affect layout and land value.
• Discharge of drainage conditions. The detailed stage to discharge a pre-commencement or pre-occupation drainage condition.
• Flood modelling. 1D and 2D hydraulic modelling — a technique that feeds the assessment, Sequential Test or drainage design where national mapping is not enough.

Early in a drainage strategy it helps to know whether the ground will take water: our free geology and ground conditions map and BRE 365 infiltration rate calculator give an indicative read before a trial pit, and the drainage calculators help size the scheme. You can screen a postcode on our flood risk map, and every report is overseen by a chartered flood risk consultant who stays involved past the report to answer objections. For the full picture of what we do, see our flood risk assessment hub and our NPPF guidance.

Lancashire flood resources and contacts

The most reliable Lancashire flood information comes from the lead authorities. For an immediate threat to life during a flood, always call 999; for a power cut during flooding, call 105.

• Check for flooding in Lancashire. Environment Agency live warnings, river levels and maps at check-for-flooding.service.gov.uk; sign up for flood warnings or call Floodline on 0345 988 1188.
• Lancashire County Council flooding. Strategy, reporting and developer guidance at lancashire.gov.uk/flooding, with the lead local flood authority surface water and SuDS advice service for major development.
• The Flood Hub. Practical Lancashire flood guidance, community resources and the river catchment partnerships at thefloodhub.co.uk/lancashire.
• North West Regional Flood and Coastal Committee. Regional investment and priorities via the North West RFCC.
• Lancashire Resilience Forum. Emergency planning and how to prepare for flooding at Lancashire Prepared.
• Live river levels. Whether the Ribble, Wyre or Lune are running high right now via our live river levels map.

For flooding from blocked or burst sewers, contact United Utilities, the water and sewerage company for the North West. For broader policy context, our notes on the Environment Agency's planning role and on flood zones 1, 2 and 3 are a good starting point.

Flood risk assessment in Lancashire: frequently asked questions