Flood Risk Assessment in Birmingham

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

Birmingham sits high on the watershed between the Severn and the Trent, so its rivers — the Tame, the Rea and the Cole — are small, fast urban watercourses that have been straightened, walled and culverted as the city grew. That makes surface water, not a great river, the source that floods Birmingham most often. We assess every source that matters here — the Tame and its tributaries, the brooks and the canal network, the surface water that overwhelms the drains, and the groundwater beneath former industrial ground — then deal directly with the Environment Agency and Birmingham City 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, 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.

Birmingham’s flood risk is driven less by a large river than by rain falling on a dense, largely paved city — surface water is the most widespread source here, and on the heavily modified Tame, Rea and Cole even a Flood Zone 1 site can need a drainage strategy before the council will grant permission.

Flood risk assessment in Birmingham at a glance

• Surface water is Birmingham’s biggest flood source. Heavy rain on a dense, largely impermeable city overwhelms the drains faster than the watercourses can carry it away, and it is now the most widespread source of flood risk in England.
• The Tame, the Rea and the Cole drain the city. All three are heavily modified and culverted in places, and all three have flooded built-up areas — the Rea through Selly Park, the Tame through Witton and Perry Barr.
• Birmingham City Council is the Lead Local Flood Authority. It leads on surface water, groundwater and ordinary watercourses; the Environment Agency leads on the main rivers. We work with both.
• Flood Zone 1 is not a free pass. Since the 2025 Planning Practice Guidance update, surface-water risk can trigger an assessment even on a Flood Zone 1 site — common right across Birmingham.

Check flood risk anywhere in Birmingham

Birmingham is outlined below. Screen any postcode in the city 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 Birmingham: the Tame, the Rea, the Cole and surface water

Surface water dominates flood risk in Birmingham. The city sits near the top of its catchments, so its rivers are small and quick rather than wide and slow, and decades of culverting and channel works mean rain has fewer natural places to go. Most sites here face more than one source at once — a watercourse, the surface water that ponds on hard ground, and sometimes groundwater beneath former industrial land.

Three Main Rivers shape the city. The River Tame runs through Handsworth, Perry Barr, Witton, Gravelly Hill, Bromford and Castle Vale before leaving towards the Trent. The River Rea rises near Frankley and flows through Longbridge, Northfield, Kings Norton, Stirchley and Selly Park into Highgate, Digbeth, Duddeston and Nechells. The River Cole drains Yardley Wood, Billesley and Hall Green through Sparkhill, Yardley and Stechford. Smaller Main River brooks — the Bourn Brook, Hockley Brook, Perry Brook, Plants Brook and Hatchford Brook among them — thread the suburbs, and many run in culverts beneath the streets. Knowing which watercourse drives the risk on a given site, and how its modified channel behaves, is the heart of a credible site-specific assessment.

• Surface water (pluvial). The dominant risk in Birmingham. Intense rain runs off roofs, roads and yards faster than the drains and culverts can take it, ponding in low spots across the suburbs. Since the 2025 PPG update, surface water on the Flood Map for Planning can trigger an assessment even on a Flood Zone 1 site, and many Birmingham sites sit in a critical drainage area.
• Rivers (fluvial). The Tame, Rea and Cole flood their narrow valley floors where development has crowded the channel. Land in Flood Zones 2 and 3 along these corridors — Selly Park, Digbeth, Witton, Stechford — almost always needs a flood risk assessment.
• Canals and infrastructure. Birmingham has one of the densest canal networks in the country, much of it raised on embankments above the surrounding land. A raised, ageing man-made channel carries a residual risk of breach or overtopping that a robust assessment should consider where people live or work below it.
• Sewers and ordinary watercourses. The surface-water and combined sewer network, operated by Severn Trent Water, backs up in heavy rain; the council’s register records hundreds of historic sewer-flooding incidents across the city. This is the Lead Local Flood Authority’s responsibility rather than the Environment Agency’s — see the role the LLFA plays.
• Groundwater. Beneath the made ground of former industrial sites, water tables can rise into basements and below-ground structures without ever showing on a river map — critical for any soakaway or basement. See groundwater flooding.

A history of flooding in Birmingham

These dated events are why the council and the Environment Agency scrutinise development closely, and why a flood risk assessment in Birmingham has to be evidence-led rather than generic. Each one reshaped local flood-risk work and the defences a developer now has to design around.

• 2008 — Selly Park. The River Rea flooded homes in Selly Park, with some residents forced out of their properties by the damage. It is the event most often cited locally on the Rea, and the trigger for the flood-storage schemes that followed.
• 27 May 2018 — the flash floods. A summer convective storm pushed the River Rea at Selly Park to a record level of around 1.82 metres — the highest reading on that gauge — as intense rain overwhelmed drains across the south of the city. It is a textbook example of how fast Birmingham’s surface-water and small-river risk can rise.
• June 2016 — Selly Park again. Further flooding on the Rea corridor underlined that ground which has flooded once tends to flood again, and kept the case for the Selly Park storage schemes alive.
• June 2026 — West Midlands flood alerts. Overnight rain on 1–2 June 2026 triggered Environment Agency flood alerts across low-lying West Midlands land, a reminder that intense summer rainfall on dry, hard ground is now a recurring threat.

A pattern runs through all of it: in Birmingham the danger is usually how fast water arrives, not how big the river is. A robust assessment treats this recorded history as evidence, not background colour.

Flood defences and schemes protecting Birmingham

Major investment has followed Birmingham’s 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.

• Perry Barr and Witton. An Environment Agency scheme of around £32 million reduces flood risk to approximately 1,400 properties, including some 950 homes, from the River Tame. It is built around a large flood-storage reservoir holding about 1.7 million cubic metres of water in the Sandwell Valley, with flood walls through Witton.
• Selly Park, on the River Rea. A £2.7 million scheme completed in January 2018 reduced the risk to more than 200 homes and businesses in the south of Selly Park, alongside a separate £4 million partnership scheme protecting over 150 properties in Selly Park North and Selly Oak through flood storage near the Bourn Brook.
• A system under pressure. Birmingham’s rivers are short, steep and heavily culverted, with little room to spread, so climate change and continued development put the network under growing strain even where defences exist.

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 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.

Planning policy and your Lead Local Flood Authority in Birmingham

Two kinds of authority set the rules. The Environment Agency leads on the main rivers — the Tame, the Rea, the Cole and their Main River brooks. Birmingham City Council is the Lead Local Flood Authority (LLFA), leading on surface water, groundwater and ordinary watercourses. Because Birmingham is a single metropolitan authority, one council covers the whole city.

A developer here deals with Birmingham City Council alongside the Environment Agency, and with the council acting as statutory consultee on surface water drainage for major development — see the role the LLFA plays. Get the drainage case wrong and the council can object, holding the application up until it is resolved, as our note on LLFA drainage objections explains.

Your assessment and drainage strategy must satisfy national policy — the NPPF and its Planning Practice Guidance — and Birmingham’s local framework: the Council’s Local Flood Risk Management Strategy, its Strategic Flood Risk Assessment and the Birmingham Development Plan, including Policy TP6 and the supplementary guidance on the sustainable management of urban rivers and floodplains. Where a higher-risk site is involved, the Sequential and Exception Tests apply, and on drainage the four pillars of SuDS and the discharge hierarchy shape what the council will accept.

What your flood risk assessment in Birmingham must show

• Risk assessed from every credible source — rivers, surface water, canals, sewers and groundwater — 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 Environment Agency’s 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, especially below the canal network and the culverted rivers.

Development and flood risk assessment in Birmingham

Birmingham is one of the most active regeneration markets in the country, and most of it is brownfield. The kind of site you bring forward shapes the assessment you need, and on hard, previously developed land the surface-water case is usually what decides the application.

• City-centre and brownfield regeneration. Schemes around HS2 Curzon Street, Eastside, Digbeth and Smithfield sit on former industrial land with high impermeable cover, culverted watercourses and the River Rea and canal corridors running through them, so surface-water drainage and made-ground groundwater are central to the assessment.
• High-density infill. Tall, tightly packed city sites leave little room for surface SuDS, so attenuation often has to go below ground — the infiltration testing and storage design have to be right first time.
• Perry Barr and the suburbs. Large residential regeneration near the River Tame sits close to Flood Zones 2 and 3, needing finished floor levels, safe access and egress, and careful treatment of the watercourse.
• Canalside and riverside schemes. Development fronting the Birmingham Canal Navigations or the Rea has to address both the watercourse and the residual risk from raised, ageing channels nearby.

Climate change is not optional here. A Birmingham assessment must apply the Environment Agency’s allowances for heavier rainfall and higher river flows 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 Birmingham

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

A flood risk assessment in Birmingham from Unda assesses every credible source — the Tame, Rea and Cole, the canal network, surface water, sewers and groundwater beneath made ground — 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 Birmingham

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 Birmingham City 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 Rea, Tame 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 made-ground and basement sites — 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 — calculates existing versus proposed runoff and proposes SuDS to hold discharge within the council’s limits and the drainage hierarchy.
• 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.

Birmingham flood resources and contacts

The most reliable Birmingham 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 Birmingham. 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.
• Birmingham City Council flooding. Responsibilities, reporting and drainage at birmingham.gov.uk/flooding; report a flooded road or blocked gully via birmingham.gov.uk/drainage.
• Strategy and developer evidence. The Strategic Flood Risk Assessment, Local Flood Risk Management Strategy and sustainable drainage guidance at the Council’s flood plans and strategies.
• Perry Barr and Witton scheme. Background on the River Tame defences at GOV.UK.
• Trent Regional Flood and Coastal Committee. Regional investment and priorities for the Trent catchment, which the Tame drains into, via the Trent RFCC.
• Live river levels. Whether the Tame, Rea or Cole are running high right now via our live river levels map.

For flooding from blocked or burst sewers, contact Severn Trent Water, which operates the public sewers across Birmingham. For broader policy context, our notes on the Environment Agency’s planning role and on critical drainage areas are a good starting point.

Flood risk assessment in Birmingham: frequently asked questions