Flood Risk Assessment in Rotherhithe

A flood risk assessment in Rotherhithe starts from the shape of the land. The tidal Thames bends around the peninsula on three sides, from the old riverside village to the entrance of Greenland Dock, and nearly all of the ground inside the river wall is defended Flood Zone 3. Within that wall lie the water bodies left by the Surrey Commercial Docks. Our consultants assess sites here for planning applications, purchases, mortgages and insurance, and prepare sequential and exception tests and surface water drainage strategies alongside them.

On this page Rotherhithe means the two Southwark wards that cover the peninsula. Rotherhithe ward runs from the village and Rotherhithe station through Canada Water, Surrey Quays station, Stave Hill and Lower Road to Southwark Park. Surrey Docks ward takes in Greenland Dock and South Dock, Surrey Docks Farm, Lavender Pond and the eastern riverside. Almost every address in the outline is in the SE16 postcode district, with a handful of SE8 postcodes at the Deptford end. Bermondsey adjoins it to the west, and Deptford, in the London Borough of Lewisham, begins past South Dock.

Four of the nine breaches that Southwark's Strategic Flood Risk Assessment models in the river wall face the Rotherhithe peninsula. The council's 2020 Level 2 SFRA rates a breach on the Gasometer, Decathlon and Surrey Quays allocations as a danger to all.

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

Where the river wall could fail: four breach points on the Rotherhithe frontage

The defences are strong. A Rotherhithe site is therefore judged on what would happen if they failed. Southwark's Strategic Flood Risk Assessment, adopted in March 2017, puts the protection given by the Thames Barrier and the walls at about a 1-in-1,000 chance of combined tidal and river flooding in any year. Planning still treats the peninsula as floodplain, because a wall can be overtopped or can give way.

• Four modelled breaches face the peninsula. The Environment Agency's 2014 breach model, which the SFRA relies on, opens 20 m gaps at Fishers Sufferance Wharf near the old village, at Lower Globe and Normandy Wharf and at Sunderland Wharf on the northern bend, and at Commercial Pier Wharf on the eastern frontage. Each is run with present-day, 2065 and 2100 water levels.
• A site away from those wharves may need its own test. The SFRA asks developers inside the breach extent to consider a site-specific breach assessment, unless one of the modelled locations already covers the site or local levels and flow paths show water would not reach it. Our explainer on residual flood risk shows how that evidence is used.
• Gauges either side of the bend. Upstream readings come from the Environment Agency's Tower Pier gauge. Downstream, the Charlton gauge has a highest recorded level of 4.74 m against a statutory defence level of 5.18 m, and alerts become possible once the river passes 4.40 m there.
• The wall will have to be raised. Rotherhithe and Canada Water are named in the Thames Estuary 2100 Wandsworth to Deptford policy unit, where policy P5 applies. By 2050 the owners of the tidal defences should adapt them and raise them where required, and by 2030 the council should plan with residents how its riverside will look. Our article on Thames Barrier closures and its future covers the barrier downstream.
• Riverside plots give up depth to the wall. Southwark Plan policy P68 keeps new development on the Thames frontage 10 m back from the defence wall, and the 2020 Level 2 SFRA asks for a 16 m strip along the river corridor. On a wharf off Rotherhithe Street, that strip comes out of the plot before any floor level is fixed.

Check an SE16 address from the village to South Dock

Type a Rotherhithe postcode into the map to screen it against Environment Agency data for rivers and the sea, surface water and reservoirs, or use our full flood risk map anywhere in England. The coral outline follows the Rotherhithe and Surrey Docks wards, with Bermondsey past its western edge and Deptford beyond South Dock. The planning flood zone leaves the defences out, while the government's long-term service takes them into account, so the two can disagree about the same flat (what the Flood Map for Planning shows).

Docks, channels and rain: the flood sources inside the wall

Since 2006 most recorded flooding on the peninsula has come from rain rather than the tide. Southwark's 2022 Surface Water Management Plan marks particular surface water risk along Rotherhithe Street and a cluster of incidents on Lower Road near Surrey Quays station. It also notes that two small watercourses still join the old docks to the Thames.

Soakaways are seldom the answer here. Southwark's 2020 Level 2 SFRA found very significant constraints on infiltration at the Decathlon, Surrey Quays and Croft Street sites, so most Rotherhithe drainage proposals begin with storage and a restricted outflow. Our ground conditions checker gives a first view of the geology beneath a plot. The guide to main rivers and ordinary watercourses explains who looks after channels like the one through Surrey Water.

Rotherhithe's flood record, from Silver Street in 1928 to the storm of 2016

One serious tidal flood and a run of shorter entries in council and fire brigade logs make up the peninsula's record. Every event below falls inside the Rotherhithe outline or is recorded against it, and each has its source.

1. 7 January 1928. High tide and strong winds sent the river over its banks across the Metropolitan Borough of Bermondsey, which then included Rotherhithe. The borough's medical officer of health found the flooding worst around Silver Street, Rotherhithe, where it reached four feet, and counted 1,213 houses affected borough-wide. Accounts of the 1928 Thames flood also record the Rotherhithe road tunnel submerged.
2. 10 December 2005. The Thames Barrier was not shut for this tide, and the SFRA records water coming over Southwark's northern edge before people living near the floodgates had been warned.
3. 14 June 2006. About 40 mm of rain fell in an hour, flooding parts of the borough and closing Rotherhithe station, according to the council's flood history records.
4. 20 July 2007. Heavy rain flooded Surrey Quays station, which stayed closed for three hours.
5. May 2008 and July 2010. Environment Agency groundwater records log recurring water in a Rotherhithe basement and, two years later, water seeping into a garage.
6. 23 June 2016. The London Fire Brigade attended flooding at Oscar Court on Rotherhithe Street, at several points along Lower Road and at the 7 Islands Leisure Centre.

Three Environment Agency tidal warning areas cover the outline. Deptford Creek to Rotherhithe Station takes in Surrey Docks, Canada Water and the riverside. Rotherhithe Station to London Bridge runs west from the village, and Deptford and Southwark Park includes the park. To see whether a warning is live, or to follow the Tower Pier and Charlton readings, open our live river levels map.

Canada Water and the allocated sites: what Southwark's Level 2 SFRA found

The Southwark Plan 2022 expects Rotherhithe's allocated sites, led by the Canada Water masterplan, to deliver an average of about 4,300 new homes and 186,000 m² of offices and workspace. Every one of them is on defended Flood Zone 3 land. Southwark's Level 2 SFRA, updated in July 2020 for the plan's examination, tested each site against the breach model, surface water and groundwater.

Its advice on new homes is the same for every site on the peninsula. Ground floors go at least 300 mm above the level a 2100 breach would bring, basement flats are ruled out in Flood Zone 3, and residents need a route above that level to Flood Zone 1 or a communal safe haven reached by internal stairs. Runoff is held to greenfield rates because Southwark's sewers are short of capacity. None of this stops building; it fixes floor levels, layouts and the drainage before a design team starts. British Land's Canada Water masterplan, the largest of these schemes, was approved in 2020 under application 18/AP/1604. Our guide to flood risk vulnerability classes explains why a police station, which has to keep working during a flood, is held to a stricter test than housing.

What Southwark's SFRA, policy P68 and the drainage rules ask of a Rotherhithe scheme

Southwark Council decides planning applications in Rotherhithe and is also the Lead Local Flood Authority. Its flood risk team comments on drainage, groundwater and the channels between the docks, while the Environment Agency advises on the tidal Thames and its walls. The local policy is P68, Reducing flood risk, in the Southwark Plan 2022, adopted on 23 February 2022. That plan replaced the 2015 Canada Water Area Action Plan, so an older report that relies on the action plan's policies needs updating.

• No added risk, on site or off it. A scheme has to be safe and resilient to flooding and must not move risk onto neighbours.
• Floors above the predicted water level. On land at risk, finished floors sit no lower than 300 mm above the predicted maximum water level. On the peninsula that level usually comes from the SFRA's 2100 breach modelling.
• Greenfield runoff for major development. Larger schemes reduce surface water runoff to greenfield rates through SuDS, working down a hierarchy that puts rainwater reuse, infiltration, ponds and discharge to a watercourse ahead of any sewer, with the combined sewer last.
• BREEAM Excellent for larger commercial space. Policy P69 asks non-residential development over 500 m² to reach BREEAM Excellent, which brings flood risk credits into play at Canada Water.

Southwark's SFRA, the evidence base for P68, dates from 2016 and was adopted in March 2017; the copy on the council website has a 2024 upload date, but no newer borough-wide study has replaced it (what an SFRA is for). Read with it is the council's developers' guide to surface water management, which caps discharge at the greenfield rate unless the flood risk team agrees a different figure before an application goes in.

Critical Drainage Areas carry less weight on the peninsula than elsewhere in the borough. The developers' guide expects an assessment in or near one, but the 2022 surface water management plan replaced them with catchments, and neither the Rotherhithe nor the Surrey Quays catchment holds any of the old areas. The Rotherhithe Street hotspots are the places to look closely instead; our note on Critical Drainage Areas explains the rule where it does apply.

The London Plan 2021 stands over Southwark's own plan. Its policy SI 12 asks for residual risk to be addressed and for buildings to stand back from flood defences, and SI 13 sets the drainage hierarchy, with major schemes sending a completed SuDS proforma alongside the drainage strategy. Consultation on a replacement London Plan ran from 16 July to 15 October 2026, with adoption not expected before 2028. National policy is chapter 18 of the August 2026 NPPF: policy F4 sets when an assessment is needed, the sequential and exception tests are in F5 and F6, and F8 brings in the 2025 National Standards for sustainable drainage for all development.

Do I need a flood risk assessment in Rotherhithe for my scheme?

Almost always. Nearly all of the outline is in Flood Zone 3 behind the defences, where national policy expects flood evidence with any development, so what changes from site to site is how much the report has to cover, from a short note under standing advice for a rear extension to a full breach assessment for a wharf. The common Rotherhithe cases fall like this.

Where new homes are proposed, Southwark will also look for testing alternative sites before it considers the exception test.

Reports we prepare for Rotherhithe, from the riverside wharves to Canada Water

Which report a site needs turns on how near it sits to the wall, what is being built and who has asked for it. Each report is written by chartered consultants and checked by a senior consultant before issue, and Unda Consulting Limited is a CIWEM Business Partner.

• Building inside the wall. New homes, extensions and changes of use on the peninsula need a flood risk assessment for planning that answers policy P68 and the breach evidence for the nearest modelled wharf.
• Tide, rain, docks and groundwater together. A flood risk assessment for a Rotherhithe plot sets the breach case beside the Rotherhithe Street surface water hotspots, the dock channels and water in the river deposits.
• Before exchange on a dockside flat. Warehouse conversions on Rotherhithe Street and homes around Greenland Dock prompt lender questions that a flood risk survey for property purchase answers for the building itself.
• Homes on allocated land. Housing in defended Flood Zone 3 faces the sequential and exception test, which the Level 2 SFRA applied to every Rotherhithe allocation.
• Runoff held to greenfield rates. P68 asks major schemes to match greenfield runoff, and our drainage strategy work shows Southwark Council how a scheme does it.
• Storage before soakage. With infiltration heavily constrained on the Canada Water sites, a surface water drainage strategy here usually relies on attenuation and a controlled discharge.
• Once permission is granted. Where Southwark attaches a drainage condition, we prepare the information needed for the discharge of drainage conditions.
• Between the modelled wharves. Where none of the four breach points matches a site, flood modelling can set the 2100 breach depth and speed that floor levels and refuges depend on.
• A way out, or a safe haven. The Level 2 SFRA asks for evacuation procedures and a route or refuge above the breach level, set out in a flood warning and evacuation plan tied to the Deptford Creek to Rotherhithe Station warning area and its two neighbours.
• Water rising from below. Groundwater has been recorded in a Rotherhithe basement and garage and could reach the surface at Canada Water, so podium and basement schemes benefit from a groundwater flood risk assessment.
• Cover and premiums. Aviva's constituency figures put 90.4% of properties in Bermondsey and Old Southwark, which includes Rotherhithe, at river and coastal flood risk by 2050. A flood risk assessment for insurance gives an underwriter evidence about one building.
• Before a land deal. The Level 2 SFRA rates a breach on the Surrey Quays and Decathlon land as a danger to all, so flood risk due diligence belongs ahead of an acquisition at Surrey Quays or along Lower Road.
• Shops, leisure and workspace. The Canada Water town centre and the Lower Road parades sit in defended Flood Zone 3, and in 2016 the fire brigade attended flooding at the 7 Islands Leisure Centre; a business continuity flood assessment helps occupiers prepare.
• New offices. The allocations plan around 186,000 m² of workspace and P69 asks larger non-residential schemes for BREEAM Excellent, which a BREEAM flood risk assessment supports through the Pol 03 credits.
• Sewer capacity. The Level 2 SFRA describes sewer capacity in the borough as constrained, so a foul drainage strategy should confirm the Thames Water connection early on a large scheme.
• Testing a site before you commit. With thousands of homes allocated on defended land, a flood risk feasibility study shows early how levels, refuges and drainage shape what a Rotherhithe site can hold.

Who handles flooding on the Rotherhithe peninsula, and how to reach them

Ring 999 when floodwater threatens anyone's safety, and 105 if a flood has cut the power. Day-to-day questions go to the five bodies below.

Upstream on the same bank, Bermondsey shares Southwark's SFRA and breach model, and Deptford starts past South Dock in Lewisham. Across the water, Wapping faces the western shore and the Isle of Dogs the eastern one. Our River Thames page covers the tideway as a whole, and the areas page lists every place we write about.

Rotherhithe flood risk: questions we are asked before an instruction

Unda Consulting Limited prepares flood risk assessments, sequential and exception tests and drainage strategies across Rotherhithe, from Surrey Docks and Greenland Dock to Canada Water and Surrey Quays. To talk about a site, call 01293 214444 or email enquiries@unda.co.uk.