Flood Risk Assessment in Derby

A flood risk assessment in Derby starts with the Derwent and the Markeaton Brook. The Derwent runs through the middle of the city and set a new record of 3.58 m at the Derby City gauge on 21 October 2023, while the Markeaton Brook flows under the shopping streets in a culvert and caused the great flood of 1932. Heavy rain on the city's mudstone adds surface water flooding in the suburbs. We prepare flood risk assessments in Derby for planning applications, house purchases, mortgages and insurance, and write sequential and exception tests and surface water drainage strategies for the same sites.

On this page Derby means the city as the Office for National Statistics draws its built-up area: the city centre and Pride Park, Darley Abbey, Allestree and Oakwood to the north, Chaddesden, Spondon and Alvaston to the east, Chellaston, Sinfin and Normanton to the south, and Littleover and Mickleover to the west, across the DE1, DE21, DE22, DE23 and DE24 postcode districts. Derby City Council is a unitary authority, so it decides planning applications and acts as lead local flood authority for the city; Derbyshire County Council has no role on a city site. One part of the built-up area, Stenson Fields, lies over the boundary in South Derbyshire, where the district council and the county council take those roles.

Five of the highest Derwent levels on record in Derby came in the six years to 2025, and the Environment Agency is updating its model of the river, so the flood evidence for a riverside site is still changing.

To talk about a Derby site with one of our flood risk consultants, call 01293 214444 or email enquiries@unda.co.uk.

The Derwent, the Markeaton Brook and Derby's smaller brooks

The city's 2025 Strategic Flood Risk Assessment lists 18 watercourses inside the boundary, and nearly all of them end up in the Derwent. The river enters the city at Darley Abbey, passes the cathedral quarter and Pride Park, then turns east past Alvaston and Spondon towards its meeting with the Trent at Shardlow. The brooks below cause most of the trouble away from the river.

The Derwent's course from the Peak District down through Matlock and Belper is covered on our River Derwent page. Inside the city the 2026 assessment notes that culverts on the Markeaton Brook, the Bramble Brook and an unnamed watercourse pose a residual risk of blockage or collapse, so a site near one needs more than a glance at the river flood zones. Our note on what a culvert is and who owns it covers the consents involved.

What the Derby City gauge and the Bridge Street gauge have recorded

Two Environment Agency gauges track flood levels in Derby. The River Derwent at Derby City gauge has measured the river beside St Mary's Bridge since 1935; the Markeaton Brook at Bridge Street gauge opened in 2021 on the brook west of the centre.

1. 0.58 m to 1.85 m. The normal range of the Derwent at the Derby City gauge.
2. 8 November 2019. The third-highest level on the gauge, after 100 to 125 mm of rain fell on saturated ground; the council investigated internal flooding and failed infrastructure across the city.
3. February 2022. The second-highest Derwent level on the gauge, with flooding in the city centre.
4. 1.94 m on 20 October 2023. The highest the Markeaton Brook has reached at Bridge Street, on the afternoon before the Derwent peaked.
5. 3.58 m on 21 October 2023. The highest level since records began, reached at 07:45 during Storm Babet.

The Environment Agency issues warnings for 13 flood warning areas across the city. Among them are the city centre, around the cathedral and the main shopping centre; Pride Park and the railway station; Little Chester, Eastgate and the Cattle Market; Racecourse Park and the Wyvern Retail Park at Chaddesden; Alvaston Park; Raynesway and the Spondon industrial area; Folly Road in Darley Abbey; and the Markeaton and Bramble Brooks. Our live river levels map shows both gauges and any warning in force.

Look up a Derby address, from Allestree to Chellaston

Enter a postcode in the map below to check an address in Derby against Environment Agency data for rivers, surface water and reservoirs, or open our full flood risk map for anywhere in England. The coral line is the ONS built-up area. It takes in the city suburbs and Stenson Fields, but not Breadsall, Little Eaton, Borrowash or the newest streets at Boulton Moor, and it follows the edge of the houses rather than the council boundary, so parkland such as Allestree Park sits outside it although the city council still covers it.

Derby floods on record, from the 1932 culvert flood to Storm Babet

Derby's record has two threads: the Markeaton Brook in the city centre, which caused the great floods of the 1930s, and the Derwent, which has set a run of records since 2019. The dates below come from the council, the city's flood risk assessments and the Environment Agency.

1. September 1931 and May 1932. Intense rain overwhelmed the Markeaton Brook through the centre twice in less than a year. In 1932 water stood up to about eight feet deep in places, people waded knee-deep along Sadler Gate, and early estimates of the damage reached £400,000. The local paper called it the worst flood since 1842.
2. 1938. The borough opened the Northern Flood Relief Culvert, about 2.2 km from Markeaton Park to the Derwent at Darley Park, to take surplus water from the Markeaton and Mackworth Brooks. Its inlet was upgraded in 2006.
3. 1947 to 1977. The Environment Agency's recorded flood outlines show the Derwent out of bank in Derby in 1947, 1960 and 1965, and the Cuttle Brook and Hell Brook in 1977. The 1947 floods followed snowmelt across much of England.
4. 2000. The Derwent flooded again, and the outline of that flood is on the Environment Agency's record for the city.
5. 6 July 2012. Prolonged rain raised the Mackworth and Markeaton Brooks and the groundwater beneath Markeaton, and the area flooded from both the brooks and surface water.
6. 19 July 2014. A storm put 54.2 mm of rain on the area, 17.2 mm of it in 15 minutes, and surface water flooded homes and damaged roads in Spondon and Oakwood.
7. November 2019 to February 2022. Three of the highest Derwent readings on record: November 2019, January 2021 and February 2022.
8. 20 to 21 October 2023. Storm Babet brought about 80 mm of rain across Derbyshire. The Environment Agency issued severe flood warnings for Derby. Drainage and some flood defences failed and buildings flooded, while about 1,500 properties benefited from the walls already built under the city's defence scheme.

Surface water matters as much as the river. The 2025 assessment lists the city centre, Alvaston, Allestree, Chellaston, Darley Abbey, Normanton, Littleover, Markeaton, Spondon and Mickleover as the areas most affected by surface water, several of them well away from the Derwent.

Our City Our River: Derby's flood defence scheme and the risk it leaves

Our City Our River is the council's flood scheme for the Derwent, delivered with the Environment Agency to a 1% annual chance standard. By April 2026 it had given more than 2,000 properties better protection. It comes in three packages:

• Package 1, finished. New and raised defences from the Alfreton Road industrial estate to Sowter Road, built between 2015 and 2019 and taking in Darley Fields and City Road.
• Derby Riverside, under construction. The second package runs from St Mary's Bridge to the Derby Junction railway bridge. With £35 million of government grant confirmed in February 2025, work began in May 2025 on new walls and gates for Exeter House, Meadow Road and Meadow Lane, which still rely on 1960s defences, and about 70% of the piling was complete by April 2026.
• Package 3. Chaddesden Sidings and the Derby Triangle, finished with development in 2023, plus works planned at Raynesway and Alvaston Park.
• Mill Fleam pumping station. Its three pumps ran at full capacity during Storm Babet, and the council credits the station with keeping much of the city centre dry.

None of this takes a site out of the flood zones. The Flood Map for Planning ignores defences, and the 2026 flood risk assessment of city-centre sites says its flood extents do not yet show the completed scheme. Where a site could flood if a wall were breached or overtopped, it asks for an assessment with detailed breach modelling, which is likely to lead to a flood warning and evacuation plan. Land on the river side of the new defences becomes functional floodplain, as our guide to Flood Zone 3b explains, and a scheme behind them still has to deal with residual flood risk.

Core Strategy CP2, the new CL1 and the SFRAs: the policy behind a flood risk assessment in Derby

Derby City Council decides the application and reviews the drainage as lead local flood authority. The Environment Agency comments where a site lies in Flood Zone 2 or 3 or close to the Derwent or the Markeaton Brook. The city has no internal drainage board, so there is no third body to consent works near a ditch. The government decided in July 2026 to replace the Derby and Derbyshire councils with two unitary authorities. In September 2026 it paused that decision for a national review of local government reorganisation, with no new date set, so the city council keeps both roles for now. In October 2026 the policies come from an adopted plan and a new one close to submission.

The national rules sit in chapter 18 of the August 2026 NPPF. Policy F4 sets when an assessment is needed, F5 and F6 cover the sequential and exception tests, and F8 expects every scheme to follow the 2025 National Standards for sustainable drainage. The council has not yet published a local SuDS design guide, and no critical drainage areas are designated in the city, so a Flood Zone 1 site's surface water risk is judged from the national maps and the assessment itself. For climate change, the Derwent's management catchment adds 29% to peak river flows to the 2080s under the central allowance and 39% under the higher central one.

Derby Riverside, Infinity Park and the city centre: where the new plan meets flood risk

The new Local Plan provides for at least 12,500 homes and about 130 hectares of employment land, with growth in the city centre and around Littleover, Chaddesden, Spondon and Mickleover. Several of the sites it relies on sit in the floodplain:

• Derby Riverside (Policy CC11). At least 600 homes in the plan period, and about 1,500 in the longer term, on the left bank between the centre and Bass's Recreation Ground. The policy ties the area to Our City Our River and asks for safe access and escape if the defences are breached.
• The 18 sites tested in July 2026. They include North Castleward, the Railway Station Quarter, Becketwell, the Market Place, the former Friar Gate goods yard and the university's city centre hub. Eleven are at risk from the Derwent or the Markeaton Brook and twelve lie in Environment Agency warning areas.
• Infinity Park (Policy E5). Land south of Wilmore Road at Sinfin, where large parts are at flood risk. The plan treats it as the only site able to provide strategic employment growth and requires flood alleviation and surface water drainage for the whole allocation.
• Indurent Park and Raynesway (Policies E7 and E8). The former Derby Triangle already has a flood conveyance corridor at Wyvern Way, and the Rolls-Royce expansion at Raynesway must address its flood risk through the defence scheme.

A site the plan does not allocate gets none of that strategic testing. It has to pass the sequential test itself if any part lies in Flood Zone 2 or 3, or is at risk from another source, and the area of search and the sites counted as available decide the outcome. Our page on testing alternative sites covers the process, and a Flood Zone 1 site at risk only from surface water may be spared the test, as our note on the surface water exemption explains.

Mudstone, river gravels and Severn Trent sewers: draining a Derby site

Where rain goes on a Derby site depends on the ground and the sewer it would reach. Most of the city sits on mudstone, with sand and gravel terraces along the Derwent, and the 2025 assessment treats the city as a whole as poorly permeable. The table draws on that assessment.

Policy CL1 sends surface water first into the ground, then to a watercourse, then to a surface water sewer or highway drain, and only then to a combined sewer, and it expects runoff at the greenfield rate even on brownfield land. A BRE 365 infiltration test settles whether a soakaway will work, and our ground conditions and soakaway map gives an early read before any trial pit. Drainage that misses the council's expectations is a common reason for an LLFA objection.

Which proposals need a flood risk assessment in Derby?

Whether a Derby proposal needs an assessment depends on its flood zone, its size, what it is for and whether other sources reach it. These are typical cases in the city:

Reports we prepare for riverside, culvert and suburban sites in Derby

A buyer near Darley Park, a householder in Spondon and the promoter of a riverside block all need something different. Every report is written by our chartered consultants and signed off by a senior consultant before it goes out, and Unda is a CIWEM Business Partner.

• Applications in the Derwent and brook flood zones. Homes and businesses near the river, the Markeaton Brook or the city's smaller brooks need a flood risk assessment for planning that answers Policy CP2 now and CL1 once the new plan is adopted.
• Every source on one site. A flood risk assessment for a Derby site weighs the Derwent, the culverted brooks, surface water on the mudstone, groundwater and the sewers together.
• Before exchange. Searches flag streets near the Derwent and the brooks, and a flood risk survey for property purchase looks at the house itself and its floor level.
• Homes on land at risk. New housing in the Derwent or brook flood zones, or at risk from surface water, needs the sequential and exception test before the council can approve it.
• Drainage the city council reviews. As lead local flood authority the council checks drainage itself, so most Derby applications need drainage strategy work that follows the CL1 order of outlets.
• Greenfield rates on brownfield land. A surface water drainage strategy tests the ground and sizes storage so a redeveloped site releases water no faster than a field would.
• Clearing the condition. A pre-commencement drainage condition on a Derby consent stops work starting until it is cleared, and discharge of drainage conditions provides the calculations, construction details and maintenance plan the city council wants to see.
• Levels while the Derwent model is rebuilt. With the Environment Agency updating its Derwent model and only flood outlines available for the Markeaton Brook, flood modelling sets a design level and tests a breach where the national mapping falls short.
• A way out behind the walls. Thirteen Environment Agency warning areas cover Derby, from Darley Abbey to Spondon, and Policy CC11 asks for safe escape from Derby Riverside if the defences fail, so a flood warning and evacuation plan often accompanies a scheme there.
• Homes with a flood history. After homes flooded in 2014, 2019 and during Storm Babet, a flood risk assessment for insurance gives an insurer evidence about one address.
• High groundwater by the brooks. Groundwater sits close to the surface at Markeaton, New Zealand, Alvaston and Boulton, and a groundwater flood risk assessment looks at basements and soakaways there.
• Firms in the warning areas. Pride Park, the railway station, Raynesway and the Spondon industrial area each have a Derwent flood warning, and a business continuity flood risk assessment plans how a business keeps running.
• Commercial buildings for certification. New premises at Infinity Park and Raynesway can earn BREEAM credits for flood risk, which a BREEAM flood risk assessment addresses.
• Land before an offer. Riverside sites may have to build part of the new defences into their layout, and Infinity Park needs flood alleviation across the whole allocation, so a flood risk feasibility study shows early how much land is left to build on.

Derby flood contacts: the council, the Environment Agency and Severn Trent

If floodwater puts anyone in danger in Derby, ring 999; for a power cut, ring 105. For everything else, each body below looks after one part of the city's flood risk:

Upstream, the Derwent runs through Matlock and the rest of Derbyshire, whose county council is the flood authority for Stenson Fields; downstream it joins the River Trent on its way to Nottingham. Further towns and counties appear in our list of areas.

Questions about Derby sites, floods and planning

For a plot near the river in Darley Abbey, a house in Chaddesden or employment land at Sinfin, ring 01293 214444 or email enquiries@unda.co.uk, and one of the consultants at Unda Consulting Limited will talk the site through with you.