Flood Risk Assessment in Warwick

A flood risk assessment in Warwick has to look past the river below the castle. The Avon sweeps by Bridge End, Mill Street and St Nicholas Park, but three smaller brooks, the Saltisford, the St Johns and the Gog, also run through the town, one of them in a culvert beneath the road at St Johns, and the Environment Agency issues flood warnings for each. Our consultants prepare flood risk assessments in Warwick for planning, for buyers and their mortgage lenders and for insurers, as well as sequential and exception tests and surface water drainage strategies.

Warwick on this page is the town as the Office for National Statistics drew its built-up area in 2022. That covers the old centre between the castle and the racecourse, with Emscote, Packmores, Saltisford, Woodloes Park and The Cape to the north. Bridge End lies across the river, and Chase Meadow, Heathcote and Warwick Gates spread to the south and west, all within the CV34 postcode district. Hampton Magna, Budbrooke, Barford, Leek Wootton and Bishop's Tachbrook sit outside that line, though the same councils and much of the same evidence apply to them. Planning decisions in the town rest with Warwick District Council, while surface water and drainage fall to Warwickshire County Council as lead local flood authority. Leamington Spa has a page of its own, the rest of the county is on our Warwickshire page, and every other place we write about is listed among the areas we cover.

On 12 August 2020 a thunderstorm over Warwick flooded five businesses and four homes, and water stood above kerb height across the St Johns junction with Smith Street and Priory Road, over the culverted St Johns Brook.

Send the CV34 address to enquiries@unda.co.uk or call 01293 214444, and one of our flood risk consultants will tell you which reports the site is likely to need.

The Avon at Bridge End, Mill Street and St Nicholas Park

The Warwickshire Avon comes in from Guy's Cliffe in the north, passes Emscote and St Nicholas Park, runs beneath the castle walls and leaves past Bridge End towards Barford. Five Environment Agency flood warning areas reach into Warwick, two on the river and one on each brook, and a wider alert area covers low land and roads along the Avon from Rugby to Bidford.

The Environment Agency's Warwick gauge, on the Avon upstream of the town centre, normally reads between 0.40 m and 1.46 m. Above 2.30 m low-lying land can flood; above 3.00 m, property can. Its record is 3.95 m on 10 April 1998, and the highest in its recent record came on 26 November 2012, at 3.32 m. Our live river levels map shows the gauge alongside any warning in force. The brooks are a different matter: when the county council looked into the August 2020 storm, the St Johns, Saltisford and Racecourse brooks had no gauge at all, so it could not tell how full the St Johns culvert had been.

Check a CV34 postcode on the map

The coral line follows Warwick's 2022 built-up area, from Woodloes Park in the north to Warwick Gates in the south-east. Enter a postcode to see its planning flood zone, its modelled risk from rivers and surface water and any warning in force, or open our flood risk map for an address anywhere in England.

The flood zones show where the Avon and the brooks would spread in a large flood, not what rain does on the way to them. The district's 2022 strategic flood risk assessment expects surface water to get worse in Woodloes Park and along the north side of the railway as storms intensify, and it names the west of the town by the Gog Brook, along with the land beside the Avon, as where river flooding is most sensitive to climate change.

Saltisford, St Johns and Gog: the brooks that cross the town

Each of the three brooks is a main river through Warwick on the Environment Agency's map, which makes the Agency, not the county council, the body responsible for it. Each also has a flood warning area of its own, so residents can be told when it is rising.

• Saltisford Brook. Flows from Saltisford Common past the racecourse towards the castle. The SFRA counts the embankment at Saltisford Common, built to a 1 in 100 year standard, as one of the district's two main flood defences; the other is at Midland Oak Park in Leamington. Land behind a defence is still at residual risk if it is overtopped.
• St Johns Brook. Runs down from Woodloes Park and Rothwell Road and goes underground beneath St Johns and the neighbouring roads. Road gullies and the surface water sewers empty into that culvert, so a full brook can stop the street drains from emptying. Flooding was reported upstream of the culvert in December 2019.
• Gog Brook. Comes in from Budbrooke at Hampton Road and runs past Chase Meadow to Lodge Crescent. Warwickshire County Council has carried out flood alleviation works on the brook, which the SFRA calls the Gog or Fisher's Brook, downstream of Hampton Road to protect the Tournament Fields area.

Smaller ditches and field drains feeding the brooks are ordinary watercourses, and any culvert, outfall or temporary works on one needs the county council's consent, at £50 for each structure. Policy FW1 rules out culverting an open watercourse on a new site, and our guide on what a culvert is and who owns it explains the background.

Warwick's floods on record, from Easter 1998 to Storm Henk

1. 10 April 1998. The Avon peaked at 3.95 m on the Warwick gauge, still the highest level on record there.
2. 24 and 25 June 2005. Thunderstorms brought more than 100 calls from flooded householders to Warwickshire Fire and Rescue, with Warwick and Leamington worst hit. Warwick Hospital suffered what the county's records call significant flooding, and emergency patients were sent elsewhere for several hours.
3. 26 November 2012. The gauge reached 3.32 m. The district Local Plan lists 1998, 2007 and 2012 as the floods that hit the whole district.
4. 12 August 2020. Rain at 10 to 20 mm an hour, heavier nearby, flooded nine properties. Water ran off Priory Park and down Smith Street and Priory Road to St Johns, where bow waves from passing cars pushed it over the kerb into premises with level thresholds. The surface water sewer in Priory Road surcharged and lifted a manhole cover.
5. September 2017 to July 2021. A commercial site on Cape Road, lower than the road beside it, reported flooding five times in under four years, often in rain no heavier than a two-year storm. The county council published a Section 19 report on it in January 2023.
6. January 2024, Storm Henk. The Avon overtopped at Bridge End and flooded a house through its garage and floor. One home in Mill Street flooded from surface water, and at Lynton Close in Woodloes Park one household was out of its home for 11 days.

Since 2008 the county council has logged 25 flooding incidents in the three postcode sectors that cover most of the town, CV34 4, 5 and 6, over half of them put down to drainage infrastructure rather than a river. Its map of reported flooding and the two Warwick flood investigation reports are worth reading before buying or building nearby. Our explainer on Section 19 flood investigations covers what such reports can and cannot tell you.

What a flood risk assessment in Warwick must show under Policies FW1 and FW2

Warwick has no neighbourhood plan of its own, so an application in the town is judged against national policy, Warwick District Council's 2017 Local Plan and the county council's drainage guidance, with a replacement plan for south Warwickshire now well advanced.

Policy FW1 also asks for a Water Framework Directive assessment wherever a site lies next to a watercourse, which in Warwick means any plot backing on to one of the brooks; our note on the Water Framework Directive explains what that involves. Floor levels in an assessment are set in metres above Ordnance Datum, and our guide to AOD and floor levels shows how the 600 mm figure is applied.

Clay ground, the Grand Union Canal and the castle lake

The county council's guidance is direct about it: "Warwickshire is underlain predominantly by clayey, impermeable soils and geology and as such, infiltration is rarely capable of providing the final runoff destination." River terrace sands and gravels along the Avon drain better, but they sit close to the river and its water table. Infiltration tests and winter groundwater readings come before any soakaway in Warwick is relied on, and our soakaway and ground conditions guide sets out what they involve.

The Grand Union Canal crosses the north of the town, with the Saltisford Arm reaching towards the centre. The SFRA records no breach or overtopping of the canals in the district, but it expects an assessment for a site beside a canal to consider what a breach would do. It also lists New Waters, the lake in Warwick Castle's park, among the reservoirs whose failure has to be considered, although the Reservoirs Act inspections keep that risk low.

Montague Road, Europa Way and the historic centre: what is being built

The 2017 Local Plan allocates both brownfield land inside the town and large greenfield sites on its southern edge.

• Land at Montague Road (H11). About 140 homes on brownfield land in the north of the town, where FW2 still asks for runoff to come down to the greenfield rate.
• Land west of Europa Way (H01). About 1,210 homes with a secondary school and a community stadium, between Warwick, Whitnash and Leamington, with a drainage strategy the county council has to accept.
• Gallows Hill (H46a) and The Asps (H46b). About 630 and 900 homes on the southern approach to the town, each with drainage the county council comments on as a major scheme.
• Tournament Fields and Cape Road. Employment land beside the Gog Brook and the commercial premises that flooded repeatedly on Cape Road, where a buyer or occupier needs to know the drainage history.
• The town centre. Listed and historic buildings within the conservation area, where a change of use or a basement means fitting flood measures without damaging the fabric.

Severn Trent's register of sewer flooding counts 21 incidents in postcode sector CV34 6 alone, so a scheme here needs Severn Trent's view on sewer capacity early, before the drainage layout is fixed.

Reports for Bridge End cottages, St Johns shops and the Europa Way estates

People come to us about Warwick sites when they are about to build, buy, insure or lend. Three questions sit behind the reports: is the site safe, which a flood risk assessment answers; should it be built on at all, the job of a sequential test; and where will its water go, which a drainage strategy settles.

• Applications to Warwick District Council. Homes and conversions around Mill Street, Bridge Street and Bridge End need a flood risk assessment for planning that meets FW1's 600 mm floor level and gives a dry way out.
• River, brooks, sewers and canal together. A flood risk assessment for a Warwick site brings the Avon, the three brooks, surface water, the sewers, the canal and the castle lake into one report.
• Buying in Bridge End or Woodloes Park. Streets that appear in the Storm Henk report, and homes inside a brook warning area, are where a flood risk survey for property purchase tells you how that one house would fare.
• Housing on the Avon floodplain. FW1 presumes against building in Flood Zone 3, so housing there needs a sequential and exception test before the council will weigh anything else.
• Schemes of 10 homes or more. Major applications bring the county council in as consultee, and a drainage strategy has to meet its October 2026 guidance as well as FW2.
• Runoff near St Johns and Cape Road. A surface water drainage strategy holds a new site's discharge to the greenfield rate, so the scheme does not send more water into streets where it already gathers.
• Conditions on a Warwick consent. Where permission comes with a drainage condition, discharge of drainage conditions provides the calculations, exceedance routes and maintenance plan the council asks for.
• Levels for the brooks. The Saltisford, St Johns and Gog are main rivers with little public level data, and where the national maps leave a plot's flood level uncertain, flood modelling works it out.
• Buying commercial property. At Tournament Fields beside the Gog Brook, or among the St Johns shops where five businesses flooded in 2020, flood risk due diligence weighs river and surface water risk before a purchase or a loan.
• Keeping a business running. The Cape Road premises that flooded five times in under four years show how exposed a low yard can be, and a business continuity flood risk assessment plans for the next storm.
• Insuring a Warwick home. Owners in Bridge End, Mill Street or Lynton Close, all in the county's Storm Henk report, can use a flood risk assessment for insurance to show an insurer how their own building stands.

Who answers when the Avon or a brook rises in Warwick

Anyone trapped or threatened by water at Bridge End, St Johns or anywhere else in town should ring 999, and a power cut goes to 105. Floodline, on 0345 988 1188, has warnings and advice at any hour, and anyone living near the river or the brooks can sign up for flood warnings for their own warning area. Which body to call otherwise depends on where the water came from.

Flood risk assessment in Warwick: fees, records, brooks and the new plan

A senior consultant checks and signs every Warwick report before it goes out; the consultants who prepare them are chartered, and Unda Consulting Limited is a CIWEM Business Partner. Email enquiries@unda.co.uk or call 01293 214444 about a site anywhere from Woodloes Park to Warwick Gates. Downstream on the Avon we cover Stratford-upon-Avon, and to the north Coventry.