Flood Risk Assessment in Shrewsbury

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

Shrewsbury sits inside a tight loop of the River Severn, the longest river in the United Kingdom, which wraps almost the whole way around the medieval town centre before heading on towards Ironbridge and Worcester. We assess every source that matters here — the Severn itself, the Rea Brook and the other tributaries that join it around the town, the surface water that ponds in low-lying streets, and the groundwater held in the river gravels — then deal directly with the Environment Agency and Shropshire Council 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, a 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.

Flood risk assessment in Shrewsbury at a glance

• The Severn loops right around the town. Shrewsbury's centre sits on a near-island inside a horseshoe meander of the River Severn, which is the single biggest reason the town has flooded so often.
• The Severn reached 5.25 m at Welsh Bridge in autumn 2000, its highest level in more than half a century, when Frankwell flooded three times in six weeks.
• Shropshire Council is the Lead Local Flood Authority. The unitary council is the statutory consultee on surface water drainage for major development, while the Environment Agency leads on the Severn itself.
• Flood Zone 1 is not a free pass. Since the 2025 update to Planning Practice Guidance, surface water risk can trigger an assessment even on a Flood Zone 1 site in the town.

Check flood risk anywhere in Shrewsbury

Shrewsbury is outlined below. Screen any postcode in and around 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.

Why Shrewsbury floods: the River Severn loop and its tributaries

River flooding shapes everything in Shrewsbury. The Severn draws on a large upland catchment in mid-Wales, then doubles back on itself in a horseshoe loop around the town centre, so water arriving from the hills has to squeeze past the same neck of land twice. Surface water and the Rea Brook add to the picture, which is why most sites in and around the town face more than one source at once.

The Severn rises on Plynlimon in the Cambrian Mountains and gathers the River Vyrnwy, the River Perry, the Rad Brook and the Rea Brook before and as it reaches Shrewsbury. After heavy rain or snowmelt on the Welsh hills, that combined flow funnels into the loop and the river backs up against its own bends, which is the textbook reason a meander town floods. Knowing which watercourse drives the risk on a given site, and how quickly it responds, is the heart of a credible flood risk assessment for planning.

• Rivers (fluvial). The Severn is the dominant risk. Frankwell, Coleham, the Quarry, Coton Hill, the riverside roads and the meadows inside the loop all sit in Flood Zones 2 and 3, where an assessment is almost always required.
• The Rea Brook. This ordinary watercourse drains the country to the south-west and floods at its confluence with the Severn in the town. The riparian responsibilities that come with a brook on your boundary are routinely raised in planning.
• Surface water (pluvial). Now the most widespread source of flooding in England. Intense rain overwhelms drains in the lower streets, and since the 2025 PPG update it can trigger an assessment even on a Flood Zone 1 site.
• Groundwater. The river gravels and alluvium along the Severn hold water tables that rise with the river and can flood low ground and basements without showing on a river map — important for any soakaway or below-ground level. See groundwater flood risk.

The town centre is the clearest case of why a single map is never enough. The Severn floodplain presses against Frankwell and Smithfield Road while the Rea Brook and the surface-water network back up behind the same high river levels, so a scheme there has to reconcile both at once. Our notes on the sources of flood risk and on how accurate flood maps really are set out how these sources interact, and the wider county picture sits on our flood risk assessment in Shropshire page.

A history of flooding in Shrewsbury

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

• 1947, 1968 and 1998. The Severn flooded Frankwell, the town centre and the lower streets repeatedly through the twentieth century, each time following the same pattern of inundation and clean-up before the next event.
• Autumn 2000 — the turning point. After the wettest autumn on record across England and Wales, the Severn peaked at 5.25 m at Welsh Bridge, its highest level in over fifty years. Frankwell flooded three times in six weeks and was under water for days, and the event drove the case for permanent defences.
• 2007. Severe summer flooding returned to the Severn valley, but earlier warnings and a faster, more coordinated response showed how far flood management had moved since 2000.
• February 2020. Storms Ciara, Dennis and Jorge in close succession sent the Severn to near-record levels through Shrewsbury and downstream, testing the town's barriers to their limits.
• 2022 onwards. Demountable barriers are now raised as a matter of routine when a flood warning is issued, and community flood groups act on warnings that once would have caught the town unprepared.

Unda's deep dive, Resilience by Repetition: 25 Years on from the 2000 Severn Floods, traces how Shrewsbury, Bewdley and Ironbridge rebuilt their defences flood by flood across the quarter-century since 2000.

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

The Frankwell flood defences and residual risk in Shrewsbury

Major investment followed the 2000 floods, and the schemes change what a development near them has to prove. A defence reduces the chance of flooding, but it never removes it, and planning policy still expects the residual risk to be assessed.

• The Frankwell Flood Alleviation Scheme. Completed in 2003 and first called into action in February 2004, it runs roughly 700 m of permanent flood wall and around 155 m of demountable barriers along the north bank of the Severn, protecting the Frankwell car park, businesses and homes.
• Designed to a 1% standard. The scheme is built to hold back a 1% annual probability (1-in-100-year) flood, with steel piling driven deep below ground to limit seepage beneath the wall.
• Built around warning time. Shrewsbury usually gets six to twelve hours of flood warning, so the demountable sections are erected in sequence as a flood approaches rather than kept permanently in place.
• It does not cover everywhere. Other parts of the loop — Coleham, the Quarry and the riverside roads — remain exposed, and the town's defences protect property without removing the underlying flood zone.

The catch for developers is the one we set out in residual flood risk: the Flood Map for Planning is drawn as if the defences are not there, so a defended site at Frankwell can still sit in Flood Zone 3. Climate change makes this sharper, which is why an assessment applies the Environment Agency's allowances over the development's lifetime, and why a raised floor level or floodable void is often part of the answer on riverside plots.

Planning policy and your Lead Local Flood Authority in Shrewsbury

Two kinds of authority set the rules. The Environment Agency leads on the River Severn as a main river. Shropshire Council, as the Lead Local Flood Authority, leads on surface water, groundwater and ordinary watercourses such as the Rea Brook — and as the unitary council it is also the local planning authority that determines your application.

Shropshire is a single unitary authority, so a developer in Shrewsbury deals with one council for planning and for local flood risk, alongside the Environment Agency and the role the LLFA plays as statutory consultee on surface water drainage. The council has also completed a more detailed Level 2 Strategic Flood Risk Assessment for the town centre, inside the river loop, which a site-specific assessment has to read against.

Your assessment and drainage strategy must satisfy national policy — the NPPF and its Planning Practice Guidance — and the local framework: Shropshire Council's Local Flood Risk Management Strategy, its Strategic Flood Risk Assessment and adopted Local Plan policies CS18 and MD2. Where a higher-risk site is involved, the Sequential and Exception Tests apply, and the four pillars of SuDS shape what the council will accept on drainage. Getting the drainage hierarchy and runoff calculations right from the outset is the surest way to avoid an LLFA drainage objection.

What your flood risk assessment in Shrewsbury must show

• Risk assessed from every credible source, using the Flood Map for Planning, the Shrewsbury Level 2 SFRA 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 on the floodplain.
• Residual risk managed, with safe access, egress and finished floor levels above the design flood level plus freeboard.

Development and flood risk assessment in Shrewsbury

Shrewsbury is the county town and the focus of much of Shropshire's growth, 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.

• Town-centre and riverside regeneration. Conversions, infill and change-of-use schemes around Frankwell, the Smithfield and the riverside frequently sit in Flood Zones 2 and 3, needing finished floor levels, safe access and egress, and often compensatory flood storage.
• Edge-of-town housing. Greenfield and urban-extension sites on the slopes around the loop turn on surface water and the smaller brooks, where a sustainable drainage strategy carries the application.
• Rural and agricultural schemes. Barn conversions and new builds across the surrounding countryside often hinge on an ordinary watercourse or surface water rather than the main river, and on the right drainage information.
• Employment and commercial land. Larger sites with extensive hardstanding make the surface-water drainage strategy central, with runoff held back to protect the Severn and Rea Brook downstream.

Climate change is not optional here. A Shrewsbury assessment must apply the Environment Agency's allowances for higher river flows and rainfall 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 the price, 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 whether you can do your own assessment explains where the line falls.

How Unda helps with flood risk assessment in Shrewsbury

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

A flood risk assessment in Shrewsbury from Unda assesses every credible source — the Severn, the Rea Brook and other ordinary watercourses, surface water and groundwater — 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 Shrewsbury

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 Shropshire Council. 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 Severn 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 after a flood near the river.
• 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 sites on the Severn gravels 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, as our note on what the Yatton judgment means for planning explains.

Drainage strategy and SuDS

• Sustainable drainage strategy (SuDS). Surface-water engineering that calculates existing versus proposed runoff and proposes SuDS to hold discharge within Shropshire Council's 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 of the Severn 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.

Shrewsbury flood resources and contacts

The most reliable Shrewsbury 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 Shrewsbury. Environment Agency live warnings and river levels for the town at check-for-flooding.service.gov.uk; sign up for flood warnings or call Floodline on 0345 988 1188.
• Shropshire Council flood risk and planning policy. Strategy, SuDS guidance and the Shrewsbury Level 2 SFRA at shropshire.gov.uk.
• Report a flooding issue. Surface water and ordinary watercourse problems to Shropshire Council as Lead Local Flood Authority.
• Severn at Shrewsbury flood warning area. The Environment Agency's target area for the town centre is published at check-for-flooding.service.gov.uk.
• Live river levels. Whether the Severn is running high right now near a postcode via our live river levels map.

For flooding from blocked or burst sewers, contact Severn Trent Water. For broader policy context, our notes on the Environment Agency's planning role and on the recent Shropshire canal breach near Whitchurch are a good starting point for how infrastructure and residual risk are weighed locally.

Flood risk assessment in Shrewsbury: frequently asked questions