Flood Risk Assessment in Ferndown

A flood risk assessment in Ferndown, Dorset, starts with rainwater rather than rivers. The town sits between the Uddens Water to the north, the Moors River to the east and the Stour valley to the south, and almost none of its built-up area falls in a river flood zone. Yet when Dorset mapped deep surface water flooding in 2011, Ferndown ranked 13th in the county.

Our consultants write flood risk assessments in Ferndown for planning, for home and business buyers and their lenders, and for insurers, as well as sequential and exception tests and surface water drainage strategies. Here Ferndown means the built-up area the Office for National Statistics maps, mostly in the BH22 postcode district, with the industrial estate in BH21. Ameysford straddles its northern edge, Tricketts Cross, Longham, Hampreston and Stapehill are in Ferndown Town parish but outside it, and West Parley lies just south.

Dorset's 2011 preliminary flood risk assessment counted 164 homes and 96 other properties in Ferndown inside the outline of a 1 in 200 surface water flood more than 30 cm deep.

To ask about a Ferndown site, ring 01293 214444 or send the address and plans to enquiries@unda.co.uk, and a consultant will tell you which reports the scheme is likely to need.

Why rain, not rivers, shapes a flood risk assessment in Ferndown

On the Environment Agency's Flood Map for Planning, the town barely registers. Our own overlay of that map on the ONS outline, run on 2 November 2026, found about 2,500 m² of Flood Zone 2 or 3 inside the built-up area, well under 0.1%, all of it on the northern edge towards the Uddens Water. Across the whole parish the picture changes: about 2.8 km², roughly 15% of the land, is in Flood Zone 2 or 3, and about 70% of that lies along the Stour around Longham and Hampreston.

The Flood Map for Planning covers rivers and the sea only, as our guide to flood zones in England explains. A Ferndown plot can therefore sit in Flood Zone 1 and still lie on a surface water flow path, which is why the council's surface water maps matter as much here as the flood zones.

Finding a BH22 or BH21 address on the map

Type a Ferndown postcode into the map to see river, surface water and reservoir flood extents around it, or use our full flood risk map for anywhere in England. The coral line follows the ONS built-up area, which takes in the industrial estate but stops short of Tricketts Cross, Longham and the Stour fields.

The Uddens Water, the Moors River and the Stour around Ferndown

In the words of the East Dorset Local Plan of 2002, the Moors River runs to the east of Ferndown and its tributary, the Uddens Water, to the north, where the bypass follows its valley and it divides the town from West Moors. The Environment Agency's main river map follows the Uddens Water corridor within about 150 m of the town's northern edge, and the Moors River further east. South of the town lies the Stour valley, with Bournemouth beyond it. None of the three runs through the built-up area itself, so smaller drains and culverts there are the council's to manage as lead local flood authority.

Since October 2017 the Environment Agency has measured the Uddens Water at Ferndown Tricketts Cross. Its usual range tops out at about 1.48 m; on 27 January 2026, during the wet winter that included Storm Chandra, it reached 2.495 m, the highest on its record. No Environment Agency warning area covers the built-up area. On the Stour, the warning for the Lower Stour from Longham to Christchurch names Parley, Hampreston and Ferndown. Our live river levels map shows the Tricketts Cross gauge with the Moors River at Hurn and the Stour at Wimborne and Throop.

Work on or next to a watercourse can need consent before it starts; our explainer on main rivers and ordinary watercourses sets out which body deals with which.

Drainage floods in the town and Stour floods across the parish

The Environment Agency's Recorded Flood Outlines split neatly in two around Ferndown. Inside or just outside the town they are small and caused by drainage; out in the parish they are wide and caused by the Stour leaving its channel:

1. January 1959. The Stour spread over low fields in the south of the parish.
2. 1 March 1979. Local drainage and surface water flooding inside the northern part of the town, in BH22 9.
3. May and December 1979. Two Stour floods covered about 41 ha and then 55 ha of the parish's southern fields.
4. December 1989. The Stour flood between Corfe Mullen and Christchurch took in about 89 ha of the parish.
5. 23 to 26 December 1999. Drainage flooding inside the town again, a few streets east of the 1979 outline.
6. 7 December 2000. Another drainage flood recorded just beyond the northern edge of the outline.
7. February 2009. On 11 February the Stour went out of bank across about 105 ha of the parish, around Longham and Hampreston.
8. Winter 2013 to 2014. On Christmas Eve 2013 a main river came out of its channel near Tricketts Cross, just beyond the outline, and from January to late February 2014 the Stour flooded about 63 ha of the parish.

The outlines do not count properties. The Environment Agency's Dorset Stour Catchment Flood Management Plan of 2012 records floods at Ferndown and Longham among others, notes 80 properties flooded in Iford, Longham and other hamlets in November 2002, and lists an action to develop a surface water management plan for Verwood, Ferndown and St Leonards.

Sewers, heath and pumping stations: drainage on Ferndown sites

Most Ferndown schemes are decided by where their surface water goes, and the evidence points to four limits:

• Network capacity. The council's 2010 area profile for Ferndown and West Parley says some flooding in the built-up area comes from insufficient sewer or pumping station capacity, and that new development should consider new infrastructure.
• Protected heath and rivers. The 2002 Local Plan required oil and grit interceptors on new industrial land, because estate drains discharge towards the Uddens Water and the Moors River, and asked that drainage works at Bracken Road spare the wet heath of Uddens Heath SSSI.
• Groundwater in a wet winter. On permeable ground a soakaway can work in summer and fail in February, once the water table rises. Readings across a winter settle the question before the layout is fixed.
• The lane that becomes a stream. Comments on the 2012 Core Strategy consultation described Ridgeway Lane in West Parley turning into a small river in winter rain, the kind of local flow path an assessment needs to trace.

Our ground conditions and soakaway checker gives a first look at a plot, and our article on BRE 365 infiltration testing explains the test that follows. Where a sewer connection is the only route, the guide to sewer flooding covers what the water company will look at.

How a flood risk assessment in Ferndown is judged under East Dorset policy

Dorset Council is the planning authority for Ferndown and also its lead local flood authority. The new Dorset-wide plan is years from adoption, so the Christchurch and East Dorset Core Strategy of 2014 still applies, and its account of flood risk lists the Uddens Water and the Moors among the rivers that flood regularly.

An assessment is needed in Flood Zone 1 too when a site exceeds a hectare or faces surface water risk, which in Ferndown covers much of the infill work. The council's Level 1 SFRA is the starting point, and our article on what an SFRA is explains its role. For drainage, the 2025 National Standards sit behind policy F8.

Holmwood House, Coppins Nursery and the industrial estate

The Core Strategy, as modified by its inspector, allocated two new neighbourhoods south of Ferndown: about 150 homes beside Holmwood House and about 40 at Coppins Nursery. Allocations of that size are likely to exceed a hectare, which brings an assessment whatever the flood zone, and they need a surface water drainage strategy that copes with the sewer limits noted above.

Much of Ferndown's development is commercial. The council's 2010 profile called Ferndown Industrial Estate the district's largest employment area, at 57.34 ha with more than 400 businesses. Extensions, new units and changes of use there bring their own questions: how much extra roof and yard area drains to the same outfalls, and how that water is cleaned before it reaches the heath streams.

Flood and drainage reports for Ferndown, from Ameysford to Longham

Which report a Ferndown site needs depends on whether it sits on a surface water flow path in the town, near the Uddens Water or out on the Stour fields:

• Rain, rivers and sewers together. A flood risk assessment for a Ferndown site weighs surface water first, because that is where the town's mapped risk sits, then the Uddens Water, the Moors River, groundwater and the public sewers.
• Applications to Dorset Council. A flood risk assessment for planning is written to NPPF policy F4 and Core Strategy Policy ME6, and checks the council's 2023 SFRA against the Environment Agency's newer mapping.
• Buying in BH22. When a search flags surface water on a Ferndown home, a flood risk survey for property purchase looks at the house itself: thresholds, the ground falling towards it and where the water would go.
• Land towards the Stour. Homes proposed on the Flood Zone 2 or 3 land around Longham and Hampreston, or beside the Uddens Water, need a sequential and exception test report as well as the assessment.
• Where runoff ends up. With sewer and pumping capacity already blamed for flooding inside the town, a drainage strategy agrees early whether a scheme drains to the ground, a watercourse or a sewer.
• Roofs, yards and new roads. A surface water drainage strategy sizes the storage and sets the discharge rate for a Ferndown scheme, including the pollution controls a site near the heaths will be asked about.
• Once permission is granted. Our discharge of drainage conditions service turns the approved Ferndown strategy into the detailed drawings, calculations and maintenance plan that clear the condition.
• Insurance. Dorset's 2011 preliminary assessment counted 164 Ferndown homes inside the deep surface water outline, and a flood risk assessment for insurance gives an underwriter the detail behind a postcode rating.
• Industrial estate deals. The same 2011 count found 96 non-residential properties in that outline, so flood risk due diligence is sensible before buying, leasing or lending on units at Ferndown Industrial Estate.
• BREEAM. New commercial buildings on the 57-hectare Ferndown Industrial Estate seeking a BREEAM rating need a BREEAM flood risk assessment for the flood and runoff credits.
• Groundwater. The Environment Agency's Stour plan describes Ferndown's sub-catchment as permeable ground where groundwater causes most flooding, so a groundwater flood risk assessment can be asked for on basements and deep tanks.

If water gets into a Ferndown home or unit

Where lives are at risk, dial 999, and use 105 if the flooding has cut the power. For everything else, the right body depends on the source of the water:

Our Dorset page covers the rest of the county. North of the Uddens Water is Verwood, and west along the Stour is Wimborne Minster. Across the river lies Bournemouth, and downstream, where the Stour reaches the sea with the Moors River in it, Christchurch. Places beyond these five are listed on the areas page.

Questions asked about Ferndown, Tricketts Cross and West Parley

From a garden plot in Ameysford to a warehouse on the estate, call 01293 214444 or email enquiries@unda.co.uk. Unda Consulting Limited's chartered consultants will say what the site needs, and every report is signed off by a senior consultant.