Policy CC/IW: Integrated water management, sustainable drainage and water quality

4.31. Integrated Water Management (IWM) is a holistic approach to water management that considers water supply, wastewater, flood risk and water quality in a coordinated way with the aim of ensuring the long-term sustainability of water resources and ecosystems. The concepts of ‘water smart communities’ and ‘sponge cities’ have similar aims. A sponge city is designed to mimic natural processes by absorbing, storing and gradually releasing rainwater, much like a sponge soaks up water. Green infrastructure is used to manage rainwater runoff to prevent flooding and improve water quality.

4.32. Figure 108 shows the interlinked components of an effective IWM system (see Figure 108). Weather pattern changes and the increasing occurrences and intensity of flooding and drought events, all of which are being influenced by global climate change, are making effective IWM increasingly important for both urban and rural environments. Therefore, it is crucial that IWM is considered at an early stage in the design process of any development. Appropriate water management measures for a particular development will depend upon the scale and nature of the development, but even at a small scale, measures such as permeable paving, green roofs and water butts can slow down the discharge of water, enable the reuse of water, and enhance biodiversity. The policy requires suitable flat roofs to be green or brown roofs. This should include garage and cycle sheds.

4.33. The surface water drainage priority set out in the policy begins with the collection of rainwater for non-potable use, which is in line with the requirements of this plan to make developments as water efficient as possible. However, the surface water drainage network must be designed without taking this into account as a form of attenuation, because at times rainwater storage could be at capacity, for example during the winter months. Infiltration should be maximised on site by way of sustainable drainage systems before moving further down the priority order where this is not possible.

4.34. Sustainable drainage systems (SuDS) are a key component of IWM. SuDS re-create the benefits of natural drainage systems, allowing infiltration and storage of water and reduce the rate and volume of water entering fluvial systems following storms therefore reducing peak flood levels. They also provide other benefits such as water filtration, which can improve water quality. Infiltration SuDS help to recharge aquifers which support the baseflows of the chalk streams and reduce the flow peak and volumes entering the Fens, which is increasingly important due to climate change. They also provide biodiversity and amenity enhancements, which can have positive implications for both human and environmental health. Ensuring that there is space for SuDS and the creation green infrastructure needs to be considered early in the design process for new developments. Details of the management, maintenance and adoption of SuDS, including who will be responsible for carrying this out will be secured through condition or planning obligation to ensure that they function effectively over the lifetime of the development. This will include removal of debris and sediment to ensure that there are no areas of standing water which will lower the risk of vector borne diseases associated with climate change.

Figure 108: Integrated Water Management (IWM) approach.

4.35. Guidance on the design of SuDs and surface water management can be found in the SuDS Manual, National Standards for Sustainable Drainage Systems, Cambridgeshire County Council’s Surface Water Planning Guidance and the Cambridgeshire Flood and Water SPD or successor documents. These documents (or their successor documents) should be referred to when designing an appropriate drainage strategy for a new development. For major development on land with surface water drainage issues, Cambridgeshire County Council, the Lead Local Flood Authority, must be consulted.

4.36. To further protect and enhance water quality, the policy also requires that engagement has been undertaken with the service provider, Anglian Water, to confirm that there is capacity for wastewater treatment at a receiving Water Recycling Centre, and capacity in the wastewater conveyancing infrastructure or that extra capacity will be provided in time to serve the new development prior to first occupation. Where necessary, phasing conditions will be attached to planning permissions to ensure that new developments are not occupied until the required capacity is in place. Applicants will need to secure a connection with Anglian Water and for major developments details should be included as part of a Utilities Statement in line with the requirements in Policy I/ID. For minor development planning applications, where required, details of a connection can be provided as part of a Sustainability Statement, a Design and Access Statement or a Planning Statement for the proposed development.

4.37. Appropriate water treatment and pollution control measures will need to form part of the surface drainage system / SuDS to prevent contamination of water on the site or downstream during the construction and operation of the development. In areas of contaminated land, soakaways and infiltration SuDS may not be suitable, and additional assessment must be carried out to identify the most suitable drainage system in order to prevent the mobilisation of contaminants into groundwater or surface water. Applicants must refer to the SuDS guidance referenced above and the Environment Agency’s groundwater protection guidance.

4.38. There is a first presumption for all development to discharge wastewater to the mains public sewers. Proposed developments should only include non-mains drainage if it can be demonstrated that a mains connection is not feasible in terms of cost and/or practicality, in accordance with National Planning Practice Guidance and Part H of the Building Regulations, because of the greater risk of failures leading to the pollution of the water environment.

For further guidance on how to submit comments, please see the Representation Guidance Note.

All comments must be received by 25 September 2026 at 5pm.