Flood Risk Assessment in Tewkesbury

A flood risk assessment in Tewkesbury starts with the two rivers that meet here, the Severn and the Warwickshire Avon. When both run high, the brooks draining Northway, Walton Cardiff and Priors Park back up behind them, so a site can flood from a brook first and then again from the river. We prepare flood risk assessments in Tewkesbury for planning, property purchase and insurance, alongside sequential and exception tests and surface water drainage strategies.

Our work here covers the whole built-up town in the GL20 postcode district: the historic centre and the Mythe, Newtown, Priors Park, Wheatpieces, Walton Cardiff, Northway and Ashchurch, as well as the riverside land at the Severn Ham and Lower Lode. For the rest of the county, see our page on flood risk assessment in Gloucestershire.

In July 2007 the Severn at Mythe Bridge reached 5.50 m, the highest level ever recorded there, and about 810 properties in the town flooded.

To talk through a site in the town, call one of our experienced flood risk consultants on 01293 214444 or email enquiries@unda.co.uk.

Why does Tewkesbury flood where the Severn and Avon meet?

The two rivers that meet in Tewkesbury are the Severn and the Warwickshire Avon. The Severn drains about 6,980 km² above the town and the Avon about 2,710 km². The Strategic Flood Risk Assessment calls their confluence the greatest source of flood risk in the borough. The Avon splits in two as it reaches the town, and the Mill Avon runs past Abbey Mill and the Quay right beside the centre.

Three brooks drain the eastern side of town: the Swilgate, the Tirle Brook and the Carrant Brook. In their lower reaches all three are Environment Agency main rivers, not ordinary watercourses, so works near them need the Agency's involvement rather than the county council's. When the Severn and Avon are high, the brooks cannot discharge and spread back across Walton Cardiff, Newtown and the edge of Northway. In 2007 some properties flooded twice. Surface water and the brooks came first, then the Severn and Avon. Our guide to main rivers and ordinary watercourses explains why the distinction matters on a planning application.

Surface water adds to the river risk. The Tewkesbury Borough Plan notes that drainage here is closely tied to river levels because of the largely impermeable ground and gentle slopes, and the county council ranks Tewkesbury parish "High" for surface water, with 50 to 75 reports of internal flooding. The town sits on mudstone and river alluvium, so infiltration is usually poor. Groundwater is a minor source here, though we still check it on the river-terrace gravels under Ashchurch. You can follow the Severn, the Avon and the three brooks on our live river levels map, and the River Severn page covers the river further upstream and down.

How high does the river have to rise before Tewkesbury floods?

Watch the Environment Agency's gauge at Mythe Bridge. It is the best guide to when Tewkesbury floods. Its normal range tops out at 2.80 m and property flooding becomes possible above 3.60 m. From there the Agency records which streets go under at each step. That tells a buyer or a planning officer more than the Tewkesbury flood map can, because it says where the water arrives first.

In January 2024, during Storm Henk, the gauge peaked at 4.83 m at 23:15 on 4 January. That was the highest level since 2007, above the peaks of December 2000 (4.71 m), February 2014 (4.61 m) and February 2020 (4.67 m). Since November 2000 the river has passed the 4.20 m Mill Avon level on at least nine separate occasions. On that record, a riverside property should expect the river at its door every few years.

When has Tewkesbury flooded?

Records of Tewkesbury flooding go back centuries. Local historians describe the November 1770 flood as "the greatest flood ever known at Tewkesbury". These are the events that matter most for a site assessment today:

• March 1947. Snowmelt and rain flooded Tewkesbury, Chaceley, Deerhurst and the land down to Maisemore, and the Mythe gauge reached about 5.3 m, the record until 2007.
• November and December 2000. Mythe Bridge reached 4.58 m on 9 November and 4.71 m on 14 December, with parts of the town affected.
• July 2007. The equivalent of two months' rain fell in 14 hours on 20 July. About 810 properties flooded in the town, and over 1,800 homes and 300 businesses across the borough. Water was over 2 m deep in places and the town centre was cut off from vehicles. Flood water reached inside Tewkesbury Abbey on 23 July.
• Mythe water treatment works, July 2007. The works flooded on 22 July and about 140,000 properties in the Tewkesbury and Gloucester area lost piped water; it was 7 August before the supply was declared safe to drink. Among the flood defences built in Tewkesbury since then is a £5.5 million perimeter wall around the works, designed to a 1-in-1,000-year standard. The national Pitt Review of the 2007 floods followed.
• November 2012 and February 2014. The Severn reached 4.53 m at Mythe Bridge in November 2012 and 4.61 m in February 2014, when the Avon at Upper Pound also rose to 4.62 m.
• February 2020. During Storms Ciara and Dennis the Severn reached 4.67 m. Flood warnings named Bredon Road, King John's Cottages, Lower Lode and the Mill Avon riverside, and parts of the A38 and A438 were closed.
• October 2023 to March 2024. New gauges on all three brooks set records within months of opening, starting with the Swilgate during Storm Babet.
• January 2024. Storm Henk took the Severn to 4.83 m. Walton Cardiff Lane, Howells Road, Swilgate Road, Northway Lane, Gander Lane, St Mary's Road, Ashchurch Road, Bredon Road and Gloucester Road were all closed on 5 January, and the borough council offered £500 recovery grants to flooded households.
• November 2024. The Vineyards and Rails Meadow car parks flooded as the gauge rose to 4.31 m.

Check a site anywhere in Tewkesbury

The map below is a Tewkesbury flood risk map built on Environment Agency data. Enter a postcode to screen a site, or open the full flood risk map to look further afield. The coral outline is the town's built-up area as the Office for National Statistics draws it, rather than the whole of Tewkesbury Borough.

The screening shows the Environment Agency's flood zones and modelled surface water risk around a postcode. It does not know a site's floor levels, access route or the depth water would reach, which is what an assessment to support the application works out.

When does a planning application in Tewkesbury need a flood risk assessment?

An application in Tewkesbury needs a site-specific assessment if any part of the site lies in Flood Zone 2 or 3, if it covers a hectare or more in Flood Zone 1, or if it sits in Flood Zone 1 but is at risk from another source such as surface water. The national tests are set by policy F4 in chapter 18 of the NPPF, the flood risk chapter of the August 2026 Framework. With so much of the town in Flood Zones 2 and 3, most riverside schemes, conversions and changes of use here meet at least one of them, and our guide to flood zones 1, 2 and 3 sets out what each zone means.

Tewkesbury Borough Council then applies its own rules, which are stricter than the national minimum in several places:

The evidence behind these rules is the 2008 Level 1 Strategic Flood Risk Assessment, the Joint Core Strategy's 2011 Level 2 study and the Borough Plan's Level 2 study of November 2017. A replacement Strategic and Local Plan for Cheltenham, Gloucester and Tewkesbury is due to go out for its Regulation 19 consultation between late October and December 2026, so a scheme submitted over the winter may be weighed against both.

Gloucestershire County Council, the Lead Local Flood Authority, has reviewed the drainage of every major development as a statutory consultee since 2015, and the national SuDS standards published in June 2025 now sit alongside its own guidance. In Tewkesbury Borough the county council also keeps land drainage consent for ordinary watercourses itself, except inside the Lower Severn Internal Drainage Board's district. Homes in Flood Zone 3 face the sequential and exception tests before anything else, and ENV2's river and rainfall uplifts follow the national climate change allowances. The 2007 flood also showed a second problem: a house can stay dry while every road out of it floods, as happened when the town centre was cut off. The planning test for that is safe access, explained in our note on dry island sites.

Where is Tewkesbury growing, and what does that mean for flood risk?

Most of Tewkesbury's growth is planned on the eastern side of the town, around Ashchurch and Northway, where the Carrant Brook and the Tirle Brook cross the land. On those sites the brooks' floodplains and the drainage shape the layout.

• North Ashchurch. In June 2025 a consortium applied for outline consent for up to 2,800 homes on about 197 ha between Northway, Ashchurch and Aston on Carrant. The Carrant Brook crosses the north of the site and a Tirle Brook tributary the south-east.
• MoD Ashchurch. The Joint Core Strategy records that parts of the Ministry of Defence site could provide up to 1,600 homes once released.
• Employment land at M5 junction 9. Tewkesbury Business Park and Ashchurch Business Park are the borough's major employment sites, alongside Northway Trading Estate and Newtown Industrial Estate, and Ashchurch Road floods once the Severn reaches 4.50 m at Mythe Bridge.
• Town-centre regeneration. Healings Mill and Spring Gardens bring new homes onto riverside and brownfield land, under the Borough Plan's regeneration policy for the town.
• Odessa Farm. About 100 homes, with all built development in Flood Zone 1 and flood alleviation to reduce Swilgate flooding downstream.

Reports we prepare for Tewkesbury sites

People commission this work in Tewkesbury when they are building near the rivers, buying in the flood zones or running a business that the 2007 and 2024 floods reached. These are the services involved, with the local reason each one applies:

• Assessing flood risk on a site. Near the confluence the rivers, the brooks and surface water all have to be checked together, which is what a site-specific flood risk assessment does.
• Planning applications. ENV2, the 2018 SPD and the Healings Mill and Spring Gardens allocations decide what a flood risk assessment for planning has to show in the borough.
• Buying a home. Property flooding becomes possible in Tewkesbury once Mythe Bridge passes 3.60 m, and a flood risk survey for property purchase tests a house against those levels before exchange.
• Sites in Flood Zone 3. New homes on the floodplain, such as Healings Mill, have to pass the sequential and exception test before floor levels and layout are looked at.
• Drainage evidence. The Water Management Statement the borough asks for is built on a drainage strategy that fits the 2018 SPD.
• Runoff limits. Greenfield sites at North Ashchurch must hold runoff to the 1-in-1 and Qbar rates, which a surface water drainage strategy has to demonstrate.
• Conditions. Where a consent in the borough carries a pre-commencement drainage condition, discharge of drainage conditions has to be agreed before work starts.
• Insurance. Riverside homes flooded in 2007 and were at risk again in 2024, and a flood risk assessment for insurance gives underwriters property-level evidence rather than a postcode score.
• River modelling. ENV2 asks for new hydraulic modelling where existing models fall short, which can mean modelling how a brook backs up behind the Severn, and we commission flood modelling where a site needs it.
• Warning and evacuation. The town centre was cut off in 2007 and nine roads closed in January 2024, so a riverside scheme that relies on warnings for safe access needs a flood warning and evacuation plan.
• Commercial buildings. New units on the M5 junction 9 employment land that are aiming for a BREEAM rating need a flood risk assessment for BREEAM to earn the flood credit.
• Business premises. Industrial units at Walton Cardiff flooded in 2007, and a business continuity flood risk assessment helps occupiers on Ashchurch Road and the trading estates plan for the next one.
• Land with potential. Landowners around Ashchurch weighing up the garden communities land can start with a flood risk feasibility study before committing to a scheme.

The same Severn floods reach the city downstream, covered on our page for flood risk assessment in Gloucester, and upstream at Upton-upon-Severn. The Mythe works also supply Cheltenham, which has its own page on flood risk assessment in Cheltenham. All our area pages are listed in our flood risk assessments by area.

Who manages flood risk in Tewkesbury, and who do you call?

Responsibility in Tewkesbury is split between several bodies, and which one you call depends on where the water is coming from. The Environment Agency deals with the Severn, the Avon and the lower brooks; the county council deals with surface water and the smaller ditches.

The Environment Agency issues separate flood warnings for the River Severn at Tewkesbury and for the Severn Ham. You can sign up for flood warnings by phone, text or email. To check whether Tewkesbury is flooded today, the Agency's Tewkesbury page shows every warning in force. If water is entering a home or lives are at risk, call 999. For a power cut, call 105.

Your Tewkesbury flood risk questions answered

Send us the address of a scheme by the Mill Avon, a house in Walton Cardiff or a unit on Ashchurch Road, and our consultants will look at it against the gauge record and the Borough Plan. Call 01293 214444 or email enquiries@unda.co.uk and we will come back to you within the hour.