Flood Risk Assessment in Godalming

Godalming sits on the floor of the River Wey valley, where fluvial, surface-water and groundwater flooding have shaped where water goes since the benchmark flood of 1968. A flood risk assessment in Godalming shows your planning authority that a development will stay safe from flooding for its whole lifetime, and that it will not push flood risk onto anyone else. Unda prepares these assessments for planning, property purchase, mortgage and insurance, and BREEAM, alongside the sequential and exception tests and surface-water drainage strategies (SuDS) that a town built around the Wey so often needs.

Flooding here rarely comes from one direction. The Wey and the Ock drive the fluvial risk, surface water runs off the valley sides into the town centre, and groundwater rises through the permeable Greensand. We assess every source that matters on your site, then deal directly with the Environment Agency and with Surrey County Council as Lead Local Flood Authority, guiding architects, planning consultants, developers and landowners through to approval.

Godalming has been defended since 2019 by a 525-metre flood scheme, yet the Flood Map for Planning is still drawn as if it were not there — so on most valley-floor sites it is residual risk, not the wall, that governs what you can build.

If you need a quote or want to talk a Godalming site through, contact one of our experienced flood risk consultants on 01293 214444.

Flood risk assessment in Godalming at a glance

• Most valley-floor sites face more than one source. Fluvial, surface water and groundwater flooding all occur in Godalming, and sites near the Wey often face two or three at once.
• Central and southern Godalming sit in Flood Zones 2 and 3. The Wey and the Ock place much of the low ground through the town in the medium- and high-probability flood zones on the Environment Agency Flood Map for Planning.
• The Lammas Lands are functional floodplain. These water meadows store and convey Wey floodwater and are protected as working floodplain, which heavily constrains what can be built on or near them.
• The town is defended, but the map is drawn as if it is not. The 525-metre Godalming Flood Alleviation Scheme was completed in 2019, yet the Flood Map for Planning still shows present-day, undefended risk — so residual risk governs every assessment.
• Surrey County Council is your Lead Local Flood Authority, a statutory consultee on surface water drainage for major development, with its own SuDS guidance and a Surface Water Drainage Statement pro-forma.

Flood risk across Godalming: the River Wey, the Lammas Lands, surface water and groundwater

Godalming faces three main sources of flooding, and they often act together. The River Wey and the Ock flood the valley floor through the town; surface water overwhelms the drains and runs off the surrounding slopes after intense rain; and groundwater rises through the permeable Greensand. Most sites in and around the town face more than one of these, which is why a desktop map rarely satisfies a planning officer on its own.

The Wey flows north and east through Godalming on its way to Guildford and the Thames, joined by the Ock and a network of smaller ordinary watercourses, with the Hell Ditch carrying flow along the northern edge of the Lammas Lands. A heavy, prolonged spell of rain over the catchment becomes a flood peak in the town within a day or so, and the flat valley floor means water spreads wide rather than passing quickly. Working out which watercourse drives the risk on a given site, and how it behaves, is the heart of a credible fluvial flood risk assessment.

• Rivers (fluvial). The River Wey and the Ock flood the low ground through central and southern Godalming, around Meadrow, Catteshall, the Lammas Lands, Borough Road and the riverside between the town and Farncombe. Land in Flood Zones 2 and 3 along these corridors almost always needs an assessment.
• Surface water (pluvial). Now the most widespread flood risk in England. Intense rain runs off Godalming's valley sides faster than the drains can take it, ponding in the town centre and along low routes. Since the 2025 Planning Practice Guidance update, surface water on the Flood Map for Planning can trigger an assessment even on a Flood Zone 1 site.
• Groundwater. The permeable Greensand around Godalming raises water tables that flood low-lying ground and below-ground space without ever showing on a river map, and complicate any soakaway. The Waverley Strategic Flood Risk Assessment records historic groundwater flooding in and around the town. See groundwater flooding.
• Ordinary watercourses and sewers. Many Godalming sites sit beside a ditch, brook or culvert classed as an ordinary watercourse, which brings riparian responsibilities and, for works, consent from Surrey County Council rather than the Environment Agency.

Because these sources interact, a single national map is rarely enough on its own. Our notes on critical drainage areas and on the difference between the public flood-risk map and the Flood Map for Planning explain why a Flood Zone 1 site can still need assessment, and why the right starting point is the Environment Agency mapping read alongside the Waverley Strategic Flood Risk Assessment.

Ground that has flooded once tends to flood again, which is why a robust assessment treats Godalming's recorded flood history as evidence rather than background.

A history of flooding in Godalming

These dated events are why the Environment Agency and the councils scrutinise development on the Wey so closely, and why a flood risk assessment in Godalming has to be evidence-led rather than generic. Each one shaped the policy and defences a developer now has to design around.

• 1968 — the great South East flood. Severe flooding hit Godalming during the wider South East England event of September 1968, and it remains the benchmark flood for the River Wey through the town; the modern defences are sized against a 1968-equivalent event allowing for climate change.
• 1990 and 2000. Two further notable Wey floods affected the town, part of a pattern of recurrent valley-floor flooding through the late twentieth century and the wet winter of 2000.
• Winter 2013-14. The wettest UK winter in records going back to 1766 brought exceptional flows down the Wey. Around 84 properties in the Meadrow and Catteshall area were affected and residents were evacuated for many months, with flooding from river, surface water, groundwater and foul water acting together.
• February 2020 — Storm Dennis. High flows returned to the Wey, and the newly completed flood scheme protected around 100 properties in the town, an early demonstration of the defences in action.

The pattern that runs through all of it is persistent, systemic risk along the Wey valley floor rather than a string of isolated extreme events.

The Godalming Flood Alleviation Scheme and what it means for development

Godalming is one of the few towns on the Wey with a completed flood defence scheme. The Environment Agency built it after the 2013 flooding, in partnership with Surrey County Council, Waverley Borough Council, Godalming Town Council, Thames Water and the local Godalming Flood Group. It matters for development now, because a defended site is assessed differently from an undefended one, not because it removes the need to assess risk.

• A 525-metre flood wall. The defence runs along the north bank of the Hell Ditch and is designed to reduce flooding for an event equivalent to 1968, taking climate change into account.
• A barrier across Catteshall Road. A demountable barrier closes the defence line and the road when flood levels are high, completing the protection around Meadrow and Catteshall.
• Two pumping stations. They pick up road and land run-off and groundwater behind the wall and discharge it to the Hell Ditch at a combined rate of around 84 litres per second, so the defences do not simply trap water inside the town.
• Habitat and river restoration. The scheme included wetland creation and river restoration, reflecting the multiple benefits expected of modern flood work.

For development, the key point is residual risk. The Environment Agency's Flood Map for Planning is drawn as if the defences are not there, so a site behind the wall can still sit in Flood Zone 3, and planning policy requires the risk that remains if a defence is overtopped, fails or is bypassed to be assessed over the development's lifetime. Our explanation of residual flood risk sets out why a defended Godalming site still needs a proper assessment, and the lessons from the nearby Guildford Flood Alleviation Scheme show how live the question of flood defence remains across the Wey catchment.

The Lammas Lands: functional floodplain and what it means for your site

The Lammas Lands are the open water meadows on the edge of central Godalming, and they are one of the most important flood features in the town. At times of flood, water from the Wey runs onto the meadows and either passes into the Hell Ditch or moves down the valley before returning to the river, storing and conveying floodwater that would otherwise reach property. They are recognised as a working part of the town's flood defences, and that recognition carries real planning weight.

Land that functions as floodplain in this way is treated as functional floodplain, the highest-risk flood zone, where most new development is resisted outright. Waverley's adopted Local Plan flood policy requires development to be steered to the lowest appropriate flood risk location, to avoid increasing flood risk elsewhere, and not to constrain the natural function of the functional floodplain by impeding flood flow or reducing storage. A site on or beside the Lammas Lands therefore needs an assessment that engages directly with floodplain storage and conveyance, often supported by compensatory storage and, where higher-risk land is unavoidable, the Sequential and Exception Tests and the right vulnerability classification.

Check flood risk anywhere in Godalming

Godalming is outlined below. Screen any postcode in or around the town 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 flood risk assessment in Godalming.

Do you need a flood risk assessment in Godalming?

You need a flood risk assessment for most development in Godalming within Flood Zones 2 or 3, for sites of one hectare or more in Flood Zone 1, and increasingly for smaller Flood Zone 1 sites where the Flood Map for Planning shows surface water risk or the Waverley Strategic Flood Risk Assessment flags a critical drainage area. With so much of the valley floor in Flood Zones 2 and 3, the question on a central site is usually how the assessment is scoped, not whether one is needed. If you are unsure, send us the address and we will tell you quickly.

The detail expected scales with the application. An outline scheme needs to show the principle is sound, a full application needs design and calculations, and discharge of a condition needs full technical compliance. Our guide to whether you can do your own assessment explains where that line falls.

Planning policy and your authorities: Waverley Borough Council and Surrey County Council

Two kinds of authority set the rules in Godalming. The Environment Agency leads on the River Wey as a main river. Surrey County Council is the Lead Local Flood Authority, leading on surface water, groundwater and ordinary watercourses, and acting as a statutory consultee on surface water drainage for major development. Waverley Borough Council is the planning authority that determines the application.

Waverley Borough Council and the Strategic Flood Risk Assessment

Waverley Borough Council holds the local Strategic Flood Risk Assessment, which maps flood risk from rivers, surface water, groundwater and sewers across the borough in more detail than the national maps and sets out what the council expects from a site-specific assessment. The Wey through Godalming is modelled in detail, and the SFRA maps the valley floor, including the Lammas Lands, as high-risk floodplain. The adopted Local Plan carries the borough's flood risk policy, which applies a sequential approach, requires development to be safe and to avoid increasing flood risk elsewhere, and protects the natural function of the functional floodplain. Your assessment must satisfy this local framework as well as national policy, the NPPF and its Planning Practice Guidance.

Surrey County Council as your Lead Local Flood Authority

For major development, Surrey County Council is a statutory consultee, and its advice on surface water drainage is a material consideration the borough must take into account. An LLFA objection usually stops the application being determined until it is resolved, so getting the drainage strategy right first time is the surest way to keep a scheme moving.

• The Surrey SuDS pro-forma. The Surface Water Drainage Statement pro-forma is completed for major applications and records how a scheme follows the drainage hierarchy and the national SuDS standards.
• Greenfield runoff rates. Surrey expects discharge as close to greenfield as possible, with the proposed 1-in-100-year-plus-climate-change rate no greater than the existing 1-in-100 rate.
• The drainage hierarchy. Infiltration first, then a watercourse, then a surface water sewer, then a combined sewer, with each step down justified by evidence such as BRE 365 infiltration testing.
• The four pillars. Schemes are expected to deliver water quantity, water quality, amenity and biodiversity together, in line with the four pillars of SuDS and the 2025 national standards.
• Pre-application advice. Surrey County Council offers a chargeable pre-application SuDS service and takes SuDS queries at SuDS@surreycc.gov.uk; early engagement reduces time at the formal consultation stage.

What your flood risk assessment in Godalming must show

• Risk assessed from every credible source, using the Flood Map for Planning and the Waverley Strategic Flood Risk Assessment.
• An appropriate location, tested against the Sequential Test where policy requires it.
• Safe for its lifetime, once Environment Agency climate change allowances are applied, generally 100 years for housing.
• No increase in flood risk elsewhere, with attenuation to greenfield rates and, where needed, compensatory storage that protects the Lammas Lands floodplain.
• Residual risk managed, with safe access, egress and finished floor levels, the area where many valley-floor applications are won or lost.

Development and flood risk assessment in Godalming

Godalming sits in one of the most development-pressured parts of Surrey, and the kind of site you bring forward shapes the assessment you need. The right scope is the difference between a clean approval and a drainage objection that holds an application up for months.

• Town-centre and brownfield regeneration. Schemes around the High Street, Bridge Street, the Wharf and Catteshall Road sit close to the Wey in Flood Zones 2 and 3, needing finished floor levels, safe access and egress, and often compensatory storage or floodable design on tight urban plots.
• Riverside and Wey-corridor sites. Land along the Wey through Meadrow, Farncombe and towards Shalford carries direct fluvial risk, where hydraulic modelling and current Environment Agency data usually decide the outcome.
• Edge-of-settlement and Green Belt release. Much of the land around Godalming is Green Belt, so released sites are scrutinised closely, and surface water and ordinary watercourses often drive the drainage strategy.
• Greensand slopes and southern villages. Conversions and new builds across Busbridge, Ockford and the higher ground frequently turn on groundwater and infiltration feasibility, so check the geology early with our ground conditions checker.

Climate change is not optional here. A Godalming assessment has to apply the Environment Agency's allowances for higher river flows and rainfall over the development's lifetime, 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 house prices and insurance, and a conveyancing search is not the same thing as a planning-grade assessment. Our flood risk survey for property purchase and insurance flood risk assessment are built for exactly those situations.

How Unda helps with flood risk assessment in Godalming

We act as the accurate translation layer between your scheme and the requirements set by the Environment Agency, Surrey County Council as Lead Local Flood Authority, Waverley Borough Council and national planning policy. We are experts on how Godalming floods, not a generic report mill, and we stay involved past the report to answer objections. A flood risk assessment in Godalming from Unda assesses every credible source, from the River Wey down to surface water, groundwater and any ordinary watercourse on the boundary, 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.

The full write-up is in our project note, Environment Agency objection withdrawn for a mixed-use redevelopment in Flood Zones 2 and 3, which shows how a planning-compliant assessment supported by current Wey modelling moves a scheme from objection to approval.

Our flood risk services for Godalming

• Flood risk assessment for planning. Site-specific reports that satisfy the Environment Agency and Waverley Borough Council.
• Surface water drainage strategy and SuDS. Designed to Surrey County Council's standards and pro-forma from the first sketch.
• Groundwater flood risk assessment. A defensible design water table for Greensand and basement sites, not a guess.
• Sequential and Exception Test reports. Prepared alongside the assessment where policy requires them.
• Flood modelling. Hydraulic modelling of the River Wey where national mapping does not reflect local conditions.
• Chartered flood risk consultants. Specialists who sign their advice; read more about Unda and our wider flood risk assessment services.

Flood risk assessments for every situation in Godalming

Whatever brings you to a flood risk assessment in Godalming, there is a report scoped for it. These are distinct pieces of work, prepared to different frameworks, and we will tell you which one your situation needs.

• Flood risk assessment for planning. The site-specific report submitted with a planning application; see flood risk assessment for planning and our NPPF guidance.
• Flood risk survey for property purchase. An independent, property-specific view for buyers and their advisers, set out on our homebuyer flood risk survey page.
• Flood risk assessment for insurance. Property-level evidence for insurers and brokers; see the insurance flood risk assessment.
• Flood risk assessment for BREEAM. Structured to support Pol 03 credits on new-build schemes from the outset; see FRA for BREEAM.
• Sequential and Exception Tests. The policy tests that direct development to lower-risk land, prepared alongside the assessment; see sequential and exception test reports and our explainer on what they involve.
• Surface water drainage strategy and SuDS. A separate drainage report, not a kind of FRA, designed to Surrey's standards; see sustainable drainage strategy and design, with preliminary drainage design for outline schemes and discharge of drainage conditions after permission.
• Groundwater flood risk assessment. A defensible design water table for Greensand and basement sites, assessed within the wider FRA; see groundwater flood risk assessment.
• Flood modelling. Hydraulic modelling of the Wey where national mapping does not reflect local conditions; see flood modelling services.

Godalming flood resources and contacts

The most reliable Godalming flood information comes from the lead authorities. For an immediate threat to life during a flood, always call 999.

• Check for flooding. Environment Agency live warnings, river levels and maps, including the River Wey at Godalming, Peasmarsh and Shalford flood warning area, the River Wey level at Godalming gauge, and the national check for flooding service.
• The Godalming Flood Alleviation Scheme. The Environment Agency's scheme summary on GOV.UK sets out the defences and the flood history behind them.
• Waverley Borough Council. The council's Strategic Flood Risk Assessment and adopted Local Plan flood policy.
• Surrey County Council flooding and SuDS. The county's SuDS planning guidance and its Local Flood Risk Management Strategy.
• The Lammas Lands. The local Lammas Lands flood defence pages explain how the meadows work as functional floodplain.
• Floodline. Call 0345 988 1188 for recorded flood information and to sign up for free flood warnings; call 105 for power cuts during flooding.
• Live levels and screening tools. See whether the Wey is running high right now on our live river levels map, take a first-pass postcode screen on our flood risk map, and size a soakaway with our drainage calculators and BRE 365 infiltration rate calculator.

For flooding from blocked or burst sewers, contact Thames Water as the local sewerage undertaker. For the wider county picture, see our flood risk assessment in Surrey page, and for the neighbouring town downstream on the same river, our flood risk assessment in Guildford page.

Flood risk assessment in Godalming: frequently asked questions