Flooding & water

The human version (we wrote this, not the council)This policy protects the Chilterns Beechwoods Special Area of Conservation, an internationally important wildlife site, from pressure caused by new residents visiting it. Development within the site's zone of influence that would add 100 or more homes must undergo a Habitats Regulations Assessment. Where required, schemes must provide mitigation or avoidance measures, principally Suitable Alternative Natural Greenspace (SANG), attractive green space designed to draw visitors away from the protected area, or a financial contribution towards it. The 100-home threshold was set on the advice of Natural England.

The human version (we wrote this, not the council)This section introduces the environment chapter. The district takes its name from the Rivers Colne, Chess and Gade, which meet at Rickmansworth, and with the Grand Union Canal and many former quarry lakes the area has a complex flooding picture and a wide floodplain. Three Rivers faces flood risk from rivers, surface water, groundwater, sewers and reservoirs, and climate change is expected to increase that risk. At the same time the district lies in one of the driest parts of the UK, so development must be flood-safe and use water efficiently.

The human version (we wrote this, not the council)This policy manages flood risk and water use. Development in flood risk areas must pass national tests that steer building to the safest available land, and no new development is allowed in Flood Zone 3b, the functional floodplain. Floor levels in Flood Zones 2 and 3 must sit at least 300mm above predicted maximum flood levels, and major schemes need sustainable drainage limiting runoff to greenfield rates. Buildings must stay 10 metres from main rivers and 5 metres from other watercourses. As the district is seriously water stressed, new homes must use no more than 110 litres per person per day.

The human version (we wrote this, not the council)This policy prevents development that would cause, or be harmed by, unacceptable pollution, covering land contamination, air, water, noise, vibration, light, odour and land instability. Building on or near former landfill or suspected contaminated land is only allowed where there is no threat to future users or to groundwater. Development must not worsen air quality, particularly in the district's two Air Quality Management Areas near the M25 at Chorleywood. Noise-generating and noise-sensitive uses must be kept apart or mitigated, and external lighting must be the minimum needed, avoiding harm to neighbours, wildlife and the countryside.

The human version (we wrote this, not the council)This section sets out the employment site allocations. Evidence in the South West Herts Economic Study (2024) found no need for new office sites, and recommends resisting any loss of office space. Four existing employment areas are safeguarded: Croxley Business Park (E1), Tolpits Lane (E2), Maple Cross/Maple Lodge (E3) and Kings Langley Employment Area (E4). Two small extensions to Croxley Business Park are allocated as E5 and E6, and Leavesden Park (E7) is allocated as an employment site, protected by an Article 4 Direction that stops offices changing to homes without planning permission.

The human version (we wrote this, not the council)This policy directs development to areas of lowest flood risk and requires that it does not increase flood risk elsewhere, allowing for climate change over the development's lifetime. Proposals must take a sequential approach to choosing and laying out sites, considering flooding from rivers, surface water, groundwater and sewers, informed by the Strategic Flood Risk Assessment. Flood management must be built in from the earliest design stages, and a site-specific Flood Risk Assessment is required, with hydraulic modelling where existing flood information is inadequate.

The human version (we wrote this, not the council)This section gives the full flood risk policy and its reasoning. On sites at risk, buildings must sit in the safest areas, safe access must be shown, and floor levels must be at least 600mm above the 1% annual probability flood level plus climate change allowance. All development needs a drainage strategy, an undeveloped buffer of at least 8 metres along watercourses, and space for water through green and blue infrastructure. South Warwickshire has a history of flooding from multiple sources, and climate change is expected to make floods more frequent and severe.

The human version (we wrote this, not the council)This policy aims to reduce flood risk from new development. South Warwickshire has a history of flooding from many sources, and climate change is expected to make floods more frequent and severe. Recent canal failures elsewhere have also highlighted a residual risk of flooding from canals, which should be considered in Flood Risk Assessments where relevant. Flood risk should be avoided where possible and managed effectively where development is needed, using nature-based solutions and green and blue infrastructure. Assessments should follow the latest strategic evidence and advice from the Lead Local Flood Authority.

The human version (we wrote this, not the council)This section sets out water efficiency rules for new development. South Warwickshire is classed as an area of serious water stress, so new homes must be designed to use no more than 100 litres of water per person per day. Homes with gardens must have a water butt of at least 200 litres. Non-residential buildings over 1,000 square metres must meet the BREEAM Excellent water standard and assess options for reusing rainwater or greywater. Extensions, changes of use and farm irrigation reservoirs are also covered.

The human version (we wrote this, not the council)This policy requires developers to show that enough water supply and sewerage capacity exists, or will be provided, before new development is occupied. Applicants must consult the water company, keep surface water and foul drainage separate, and avoid harming water quality in rivers or groundwater. Major schemes need an Outline Foul Drainage Strategy showing connections, upgrades and phasing. Development near sewage works must assess odour, noise and similar impacts. New or upgraded water infrastructure will be supported where its impacts are acceptable.

The human version (we wrote this, not the council)This section explains how the water and wastewater policy will work in practice. Severn Trent Water is the water and sewerage company for South Warwickshire, and developers are urged to engage with it early because a right to connect does not guarantee that capacity exists. Any needed upgrades will be secured through planning conditions or legal agreements. Connecting surface water to foul sewers is unacceptable unless approved and no other viable option exists. A possible law change would remove the automatic right to connect surface water to public sewers.

The human version (we wrote this, not the council)This policy requires high-quality sustainable drainage systems, known as SuDS, across whole development sites to manage rainwater and cut flood risk. A drainage strategy must show that runoff is handled close to where it falls, that properties would not flood in a storm with a 1% chance of occurring in any year, allowing for climate change, and that flood risk is not increased on site or elsewhere. Blue-green corridors should be kept and improved, and brownfield sites should disconnect from combined sewers wherever feasible.

The human version (we wrote this, not the council)This section adds detail on how sustainable drainage systems should be designed. SuDS must be planned as an integral part of the site layout, favouring above-ground and dispersed features rather than reliance on one large storage feature. They should deliver several benefits at once: reducing flood risk, cleaning water through a four-stage treatment train, boosting wildlife, providing attractive amenity space and helping to cool urban areas. Drainage features should also become part of the wider ecological network.

The human version (we wrote this, not the council)This section explains the green and blue infrastructure policy and sets measurable standards. Major developments must provide a green and blue infrastructure strategy. Commercial schemes must achieve an Urban Greening Factor score of at least 0.3 and residential schemes at least 0.4. Tree canopy must cover at least 14% of commercial sites and 20% of residential sites, or improve on existing cover if that is greater. These networks support wildlife, manage flood risk, store carbon and provide accessible space for recreation.

The human version (we wrote this, not the council)This allocation covers around 92.8 hectares at South Aylesbury for approximately 1,350 homes and 5 Gypsy and Traveller pitches, made up of five land parcels planned together. It requires a 2FE primary school, a local centre, a community building with a possible police touchdown facility, and 50% green infrastructure. Land is safeguarded for the Aylesbury Southeast Link Road, now under construction, with financial contributions towards it. Detailed flood modelling is required, including measures to help protect Stoke Mandeville Hospital from surface water flooding.

The human version (we wrote this, not the council)This allocation covers a 113-hectare site at south-west Aylesbury for 1,400 homes and 5 Gypsy and Traveller pitches, with a 2FE primary school, on-site health and community facilities, a linear park and sports pitches. It requires a Southwest Link Road connecting the Stoke Mandeville relief road to the A418 Oxford Road, plus strategic flood defences and drainage. Outline permission was granted in May 2026, with construction expected from 2028, delivering fifty homes initially then 140 per year. A buffer is needed against noise from HS2.

The human version (we wrote this, not the council)This allocation covers three parcels totalling around 242.6 hectares north of the A41 at Aylesbury, including Aylesbury Woodlands. It provides approximately 1,700 homes plus sixty extra care units, around 102,800 sqm of employment floorspace including the Aylesbury Woodlands Enterprise Zone, a 4,000 sqm local centre, a two-form entry primary school, a 6,000 sqm hotel and conference facility and a 16-hectare sports village. Primary access must come from the Eastern Link Road, at least 50% of the site must be green infrastructure, and employment land is safeguarded from other uses.

The human version (we wrote this, not the council)This allocation covers around 225.5 hectares south of the A41 at Aylesbury, mainly Hampden Fields, for approximately 3,000 homes plus a sixty-bed care home or extra care facility. It includes about 6.90 hectares of employment land, two primary schools with pre-schools, a local centre, a health facility and 108.34 hectares of green infrastructure. A dualled Southern Link Road between the A413 and A41 is required, along with town-wide flood defences. Outline permission has been granted and work has started, with careful phasing needed across the merged sites.

The human version (we wrote this, not the council)This allocation describes Kingsbrook, a 306.6-hectare urban extension east of Aylesbury delivering 2,460 homes, 10 hectares of employment land, two primary schools, land for a secondary school, a neighbourhood centre and a major wetland park. Outline permission was granted in 2013 and the site is built as three villages. As of March 2025, 1,922 homes were complete with 538 remaining, and the Eastern Link Road and Stocklake Link have been finished. The whole development is expected to be complete by 2028.

The human version (we wrote this, not the council)This allocation covers around seventy-nine hectares north of Martin Dalby Way on the edge of Aylesbury for an assumed 3,150 homes. It requires a local centre, a 3FE primary school, a community hall, healthcare provision and at least 50% multi-functional green infrastructure, plus a new linear park active travel route. Development must protect the Quarrendon Scheduled Monument immediately to the south, including its grazing regime, and be landscape-led given the site's open, elevated position. Flood modelling of Hardwick Brook and Weedon Ditch is required.

The human version (we wrote this, not the council)This allocation supports redeveloping the Easton Street multi-storey car park in High Wycombe for an assumed 160 homes with around 660 square metres of shops or other commercial uses at ground level. The 0.33 hectare site is next to the railway station, so a high-density scheme with fewer parking spaces is expected. The existing parking has been shown to be surplus and does not need replacing. Flood risk is a major constraint, so bedrooms and living spaces should be on the first floor or above.

The human version (we wrote this, not the council)This allocation covers the Council Offices site on Queen Victoria Road, High Wycombe, for a mixed development of 500 square metres of offices, retail and healthcare plus an assumed 150 homes for NHS key workers. The 1.04 hectare site is in NHS ownership beside the River Wye. Because of high flood risk, housing is not allowed in the most flood-prone areas, and developers must produce detailed flood modelling approved by the Environment Agency before applying.

The human version (we wrote this, not the council)This allocation proposes an assumed 270 homes and around 1,125 square metres of town centre retail on the former Office Outlet site in High Wycombe. The 0.45 hectare brownfield site is close to the railway station, so a high-density, landmark scheme with fewer car parking spaces is expected. Housing must avoid the highest flood risk zones, and developers must carry out detailed surface water modelling and follow the Council's flood risk guidance for the site.

The human version (we wrote this, not the council)This allocation sets out a mixed redevelopment of the Chilterns Shopping Centre at Frogmoor, High Wycombe, with an assumed 300 homes above flexible shops and commercial space at ground level. Flooding is the main constraint: 91% of the 1.06 hectare site is in the highest risk flood zone, so off-site flood storage would be needed and no building is allowed in those areas. The site is in a conservation area, and Grade II listed buildings must be kept and enhanced.

The human version (we wrote this, not the council)This allocation supports an assumed 305 homes on 7.57 hectares of land north of Newton Longville, on the southern edge of Milton Keynes. The development must fund a new bus route into Milton Keynes and a 3 metre wide shared path for walking and cycling between the two settlements. Housing must be steered away from the higher flood risk zones, and the scheme must not prejudice the delivery of East West Rail, as part of the land is safeguarded for the railway.

The human version (we wrote this, not the council)This allocation sets out a large residential development of an assumed 3,780 homes on around 94.5 hectares south of Newton Leys, near Bletchley. It includes a new primary school, a local centre with community facilities and healthcare provision. Density would be highest near Milton Keynes and reduce towards the countryside. A watercourse crosses the site, so flood risk must be managed and housing is not allowed in the highest risk zone. The western part already has outline permission for up to 290 homes, granted on appeal in February 2026.

The human version (we wrote this, not the council)This allocation proposes an assumed 245 homes on 7.7 hectares of farmland east of Roman Field, on the edge of Stoke Hammond. The village's neighbourhood plan already allocates part of the site for around nineteen homes, which count towards the total. Building must avoid the flood zones in the south of the site, which should stay as green space. The scheme must also respect nearby heritage, including a listed building, the conservation area and probable Neolithic remains, and consider cross-boundary needs with Milton Keynes.

The human version (we wrote this, not the council)This allocation supports an assumed 1,240 homes on around thirty-one hectares west of Shenley Park, Whaddon, continuing the planned expansion to the east. It includes a primary school for 210 pupils with a 30 place nursery. Two ancient woodlands, Thickbare Wood and Coddimoorhill Wood, need protective buffers of 50 metres, and an archaeological dig of a Roman settlement must inform the layout. Detailed traffic modelling, likely including improvements to the A421, and extensive flood risk work are also required.

The human version (we wrote this, not the council)This allocation covers the former Inov8 site on Tingewick Road, Buckingham, a brownfield site vacant for over a decade and owned by the University of Buckingham. It is allocated for up to 2.7 hectares of academic uses including an assumed 300 student accommodation units. If the university's needs are met elsewhere, the site would instead take an assumed 125 homes. No living accommodation is allowed in Flood Zone 3, and development must respect protected trees, the River Great Ouse and Buckingham's historic character.

The human version (we wrote this, not the council)This allocation supports an assumed 30 homes at Albany Place Car Park in central Chesham. The 0.35 hectare site includes the 330-seat Elgiva Theatre, which must be re-provided in a suitable town centre location, and seventy-one parking spaces that must be replaced unless shown to be unnecessary. Flood risk is significant, with off-site flood storage required and no housing allowed in the highest risk zone. Permission also depends on mitigation being in place for the nearby Chilterns Beechwoods protected area.