Sustainable drainage systems (SuDS) are designed to control surface water run-off close to where it falls and to mimic natural drainage as closely as possible. One of their uses is to reduce the causes and impacts of surface water flooding. SuDS can include a number of different practices or mechanisms designed to drain or soak-up surface water in a more sustainable way than the conventional practice of draining water run-off through a pipe into a sewer. Practical examples include soakaways (draining water through permeable surfaces into the ground) and ponds (draining water into a surface water body).
5.Sir Michael Pitt’s review of the severe floods of 2007 made recommendations on policy changes which could help combat surface water flooding, including changes to promote the greater use of SuDS. The Act was the principal statutory mechanism for taking forward a large number of the Pitt recommendations, including to “increase the uptake of sustainable drainage systems in new developments and redevelopments, wherever possible, by introducing standards for their design, construction, maintenance and operation.” (See box below).
Flood and Water Management Act, Schedule 3:
6.The measures in Schedule 3 have not been commenced. Instead the Government has focussed on using the planning system for increasing the installation of SuDS in new developments. We consider in this chapter whether these alternative approaches are delivering the Government’s objectives effectively. Submissions diverged in opinion as to the best method of improving SuDS policies: at the heart of the debate are concerns as to whether current planning approaches are sufficient and proportionate, or whether measures in the Act should be commenced as originally intended.
7.The Government has a target of building some one million new homes by 2020 and, whilst planning frameworks aim to direct building to areas of lower flood risk, there is no blanket prohibition on development in areas likely to flood. Indeed, currently some 8% of new developments are being built in high-risk flood areas. The Government’s policy objective is to ensure that sustainable drainage systems are provided in new major developments where appropriate to minimise surface water contributing to flooding.
8.Evidence to this inquiry overwhelmingly endorsed the broad objective of using of SuDS as extensively as practicable, delivering multiple benefits for flood reduction, amenity and the environment where possible. The Government acknowledges that sustainable drainage schemes can be built and maintained as cost-effectively as traditional drainage. However, almost without exception, submissions concluded that policies were failing to achieve this objective.
9.Data on the numbers of SuDS schemes being installed are incomplete as there is currently no national monitoring of the uptake of SuDS. However, a 2014 survey by Committee on Climate Change found that only 15% of planning applications in flood risk areas referred to sustainable drainage.
10.Evidence identified a number of deficiencies in current policies contributing to fewer SuDS schemes being incorporated in new developments. These included that:
11.The concept of sustainable drainage covers a range of measures from a simple system which restricts discharge using conventional pipes, through to complex green infrastructure systems incorporating features such as permeable surfaces, ponds and swales, green roofs and rainwater harvesting. These more complex schemes, broadly defined as ‘high quality’ SuDS, can not only control water flows effectively but can also deliver other benefits. These multiple benefits, as CIWEM noted, include improved water quality and the addition of quality greenspace near to homes, providing valuable pockets of habitat for wildlife as well. However, a large number of submissions concluded that many lower quality SuDS systems are being built which miss opportunities to deliver optimum benefits for local amenity and the environment. For example, Somerset County Council expressed disappointment that schemes “overwhelmingly comprise below-ground, hard-engineered solutions”. Only 8% of respondents to a recent CIWEM survey believed that the current framework was driving high quality and effective SuDS in England. Specific reasons cited were that:
12.Not all of those submitting evidence shared these concerns. The Home Builders Federation (HBF) pointed out that some developers had installed SuDS schemes several decades ago and stated that the industry’s innovations had meant that new development had “rarely been inundated by flood water” nor had new development contributed to existing flood risk. The Federation had other concerns about the effectiveness of Government policies for delivering sufficient surface water infrastructure. It considered that WaSCs had made insufficient investment in new infrastructure despite housebuilders’ contributions of some £2.6 billion towards augmenting sewer systems—the Federation claimed that neither the companies nor the regulator, Ofwat, have accounted for how this money has been spent.
13.The HBF’s submission was also critical of fragmented policies which were hampering effective drainage provision. It considered that the Government did not demonstrate leadership to properly manage the inherent tensions between different parties, each with their own agenda. In particular, the Federation was concerned about the imposition of SuDS standards higher than those agreed by the Local Planning Authority (LPA) and the refusal by Lead Local Flood Authorities (LLFAs) to accept discharge limits to public surface water sewers even though they had been agreed by both the WaSCs and the LPA. This had led to confusion and delays in development and false accusations of developers not meeting planning conditions.
14.New development is essential to support thriving communities and it is important that plans to build a million new homes by 2020 can be delivered cost-effectively. But it is vital that development does not increase flooding. The Government purports to support the use of sustainable drainage systems (SuDS) as a method for reducing flood risk from new development as well as for delivering a range of other benefits. But its sub-standard sustainable drainage (SuDS) policies are leading to too few systems being installed in new developments, and too few of these are of high quality. This is leaving communities unnecessarily exposed to flood risk and planning approaches are failing to deliver maximum biodiversity, water quality and amenity benefits.
15.The Act’s SuDS measures remain under review by the Government and Schedule 3 has not been commenced. The Memorandum refers to the Government’s alternative approaches to promote SuDS, primarily the strengthening of planning policy from April 2015 to “ensure that sustainable drainage systems are provided in new major developments where appropriate, and that clear systems are in place for ongoing maintenance over the lifetime of the development”. Planning Practice Guidance has been amended and Defra has published non-statutory technical standards for the design, maintenance and operation of SuDS to drain surface water. Defra has also contributed to the development of the CIRIA SuDS manual which highlights the benefits of sustainable drainage.
16.However, a wide range of bodies, including WaSCs, NGOs and local authorities, considered that the planning approach constituted a weaker policy framework than the measures in the Act. The Chartered Institution of Water and Environmental Management (CIWEM) considered that the Government’s decision not to commence Schedule 3 had “created a void of effective policy”. United Utilities told us that relying on planning processes to prescribe SuDS rather than implementing Schedule 3 would not deliver a “step-change in the proliferation of sustainable drainage”. Evidence noted that strengths of a Schedule 3 framework included provisions for SuDS Approval Bodies (SABs) to require standards to be met before planning permission could be granted for new developments, with clarity over funding and responsibility for schemes long-term maintenance. Many submissions, including those from the Institution of Civil Engineers, Bath and North East Somerset Council, and Anglian Water, called for Schedule 3 to be commenced, arguing that the measures addressed a number of the barriers to the proliferation of high-quality SuDS discussed above.
17.However, other submissions expressed concern that commencement would impose additional administrative burdens. The Government’s Memorandum refers to stakeholder concerns that “housing supply could be negatively impacted” by the measures. Reservations focus particularly on the bureaucracy of SABs being required to approve new schemes prior to planning permission for new developments being granted. CIWEM considered that the Government’s fear that provisions would lead to a “surfeit of bureaucracy” had stymied commencement. The HBF considered that the Government had been right to abandon SABs and that the planning system continued to be the most effective mechanism for ensuring the delivery of SuDS.
18.Some submissions, although expressing support in principle for the use of Schedule 3 measures, accepted the Government’s decision to use alternative approaches. Thames Water for example considered Schedule 3 to be a “robust mechanism” for managing flood risk but recognised that the Government had reasons for preferring a planning-based system. The Wildfowl and Wetlands Trust submission expressed disappointment about non-commencement since the measures provided clarity around SuDS adoption and maintenance. The Trust nonetheless conceded that substantial progress could be made by alternative approaches such as strengthening policies on technical standards, connections to sewer systems and maintenance of SuDS. CIWEM supported this position: its submission stated that developers were not opposed to SuDS but, in the absence of Schedule 3 commencement, they needed the support of “stricter policy” and “better SuDS standards” if more developments were to include systems.
19.We acknowledge the views of local authorities and developers concerned about the commencement of Flood and Water Management Act measures for the approval and adoption of SuDS. We are not persuaded that it is currently essential to commence Schedule 3 of the Act in order to improve the SuDS regulatory framework. Rather, we recommend that the Government strengthens planning approaches to require SuDS schemes to be installed in all developments of more than one property so as to prevent smaller developments cumulatively adding to flood risk. Planning policies must also be significantly tightened to reduce the ability for developers to use cost or practicality reasons to opt-out from installing SuDS. Standards must require schemes to deliver multiple benefits wherever possible, including biodiversity, amenity and water quality benefits as well as simply reducing water run-off rates.
20.Witnesses identified a number of specific areas where the planning framework for SuDS could be improved, principally:
21.Technical standards for SuDS construction are non-statutory; they are set out in planning policy guidance. Witnesses note that this means that planners have no legal back-up to require developers to follow a hierarchical approach in determining the acceptable discharge solution for site. Many submissions asserted that the lack of a statutory underpinning allowed developers an opt-out if they consider SuDS to be too costly or impractical for a site. The Home Builders Federation supported nationally-consistent guidance applicable to all planning decisions but considered current standards to be “gold-plated”.
22.The Government should enshrine standards for the design of SuDS in statute to ensure that all new developments install high-quality SuDS. These standards must ensure that developments do not add to surface water flood risk and that that new drainage systems deliver biodiversity, water quality and amenity benefits.
23.Many submissions to this inquiry concluded that the current planning system had led to significant uncertainty persisting as to who is responsible for SuDS’ long-term maintenance. Developers have the option to either enter into adoption agreements with local authorities or other public bodies, or to hand over maintenance to management companies. This second option might be cheaper for the developer but witnesses were concerned that, with no oversight body such as a SAB to enforce the regime, in the longer-term management companies could abnegate their responsibilities. Companies could also go bust leaving “orphan SuDS” with no-one responsible for ensuring proper operation of the systems.
24.Stronger regulation is needed to ensure that SuDS systems are maintained effectively in the long-term. Developers can all too easily hand over responsibility for schemes to companies which are subject to no external oversight over how they maintain SuDS on the developments they manage. It is in the interests not only of those living in a new development but also those in the wider local community that SuDS systems continue to function well in order to minimise flood risk. The Government must clarify how the effective management of SuDS on private land can be better secured through robust agreements for funding and monitoring the long-term maintenance of schemes.
25.Witnesses argued that SuDS policies needed to make it easier for flood risk management bodies such as LLFAs or Internal Drainage Boards (IDBs) to adopt SuDS by clarifying their responsibilities. The Association of Drainage Authorities considered that the most practical way for improving the framework was for these types of publicly accountable statutory bodies to take on responsibility for SuDS and their maintenance.
26.Furthermore, many witnesses considered that the current framework deterred WaSCs from building and adopting SuDS by the current framework. Some WaSCs called for the statutory definition of a sewer to be amended since the current formulation arguably did not allow them to build and adopt SuDS. However, not all WaSCs would welcome SuDS responsibilities. Southern Water, for example, was concerned about maintenance costs and liabilities falling on sewerage companies. Nonetheless the balance of evidence to this inquiry supported an amendment which would make it clear that sewer definitions included SuDS.
27.Barriers to Water and Sewerage Companies (WaSCs) being able to adopt SuDS must be removed: the definition of a sewer must be amended to remove any uncertainty over WaSCs’ legal ability to build or adopt SuDS. Such adoptions must be accompanied by robust agreements for the funding by private developments of ongoing maintenance costs incurred by WaSCs.
28.We called in our Future flood prevention report for WaSCs to become Water and Drainage Companies with a remit for local surface water management: this would incentivise the installation of new, high-quality SuDS systems. Bringing local flood management and water management together would drive companies to adopt holistic solutions such as SuDS since these would often provide the most cost-effective methods for delivering their regulated range of obligations.
29.The Committee has in previous reports supported water industry calls for an end to the automatic right for surface water discharges from new development to connect to the traditional sewer system. This would ensure that high-quality alternative drainage schemes would be considered before connection to the traditional system was considered. Wales is proposing to take this approach, as Northern Ireland has already. Scotland has a strong policy in presumption of SuDS.
30.Evidence to this inquiry on balance strongly supported the ending of the right to connect. For example, Water UK told us that retaining the right to connect gave “precedence to development over controlling flows to the network and thus over sewer flooding risk”. This appeared to set the wrong balance for creating long-term resilience in the sewerage network. Severn Trent considered that developers saw connection to the WaSC sewer system as an easier option than connecting to a SuDS non-sewer outfall such as a ditch or watercourse. The water company considered that connections to WaSC sewers should only be permitted once all other options had been exhausted.
31.The automatic right for new developments’ surface water drainage to be connected to conventional drainage systems must be repealed. This would provide a strong incentive to developers to install SuDS systems in far greater numbers.
32.It is vital that delivery of the policy framework is properly resourced but many witnesses considered that a lack of resources and expertise within the planning system presented a barrier to development of high-quality SuDS. The HBF questioned the competencies of the bodies tasked with SuDS roles, and asserted that the Act failed to recognise the existing expertise within WaSCs for example. The Federation considered the new regime to be “insufficient to serve the needs of the house building industry”. Skills problems could be ameliorated by introducing statutory standards since this would place a stronger requirement on financially-constrained local planning bodies to prioritise resources on developing capacity and expertise to ensure the enforcement of SuDS conditions.
33.Water UK noted that creation of a SAB as required under Schedule 3 would have led to centres of excellence being developed. However, the development of specialist skills can also be supported under voluntary approaches, for example through joined-up working across local authorities to disseminate best practice.
34.Improvements to the SuDS policy framework must be matched by effective local delivery arrangements. Under a planning-led approach, it is vital that all Local Planning Authorities and Lead Local Flood Authorities have sufficient skills and expertise on SuDS to ensure that high quality schemes are developed and standards for their construction and maintenance are enforced effectively. The Government must set out the actions it is taking in partnership with the local government sector to ensure that all local authorities with SuDS roles can develop sufficient capacity and expertise.
35.It should be noted that in this inquiry we considered SuDS for new developments only. However, with new developments only accounting for some 1% of land use change each year, there is considerable scope to improve the contribution of existing developments to minimising surface-water run-off. Policies are therefore needed to promote the retro-fitting of SuDS in existing built-up areas.
36.Sewer overflows and surface water flooding are exacerbated by the low prevalence of SuDS installed in existing properties. It is clear that approaches are needed to promote the use of sustainable drainage not just in new developments but for all urban properties. Otherwise, costly new infrastructure could be required to avoid flooding in dense built-up areas as a result of the increasingly intense rainfall likely to affect the UK in future because of climate change.
37.During the passage of the Housing and Planning Act 2016, Ministers acknowledged concerns over the effectiveness of SuDS policy and supported an amendment to the Bill requiring the Government to carry out a review of planning policies’ impact on SuDS. Ministers have commenced this review, however witnesses to this inquiry were concerned that it is being held without full stakeholder involvement or a definite timescale for either its completion or for the implementation of its findings. Our Future flood prevention report recommended that the review lead to outcomes as robust as those which would result from implementation of the Schedule 3 regime.
38.The Government has conceded the need to review the adequacy of its current approaches. Departments must set out a clear timetable for completion of this work and for the implementation of findings in light of the forthcoming General Election. Consultation arrangements must enable all interested parties to contribute their views. The review must take into account the recommendations in this Report together with the recommendation in our previous Future flood prevention report.
39.Our successor Committee may wish to review progress in improving the SuDS regime in 18 months’ time to ensure that a far higher proportion of new developments are installing high-quality SuDS. If policies fail to provide as robust a regime as that under the Flood and Water Management Act by the end of 2018, we consider it would be appropriate for that Committee to consider recommending commencement of Schedule 3 measures.
5 , Section 31 and Schedule 3
6 Zurich Insurance ()
8 Chartered Institution of Water and Environmental Management ()
9 Committee on Climate Change Adaptation Sub-Committee, , 2014
10 Written Statement by the Secretary of State for Communities and Local Government, 18 December 2014, to be read in conjunction with para 103 of the
11 Association of British Insurers (
12 As above
13 Swales are shallow, broad and vegetated channels designed to store and/or convey runoff and remove pollutants. They may be used as conveyance structures to pass the runoff to the next stage of the treatment train and can be designed to promote infiltration where soil and groundwater conditions allow
14 Chartered Institution of Water and Environmental Management, ? February 2017, p26
15 Somerset County Council ()
16 Chartered Institution of Water and Environmental Management, ? February 2017, p28
17 Somerset County Council ()
18 Home Builders Federation () para 4
19 Home Builders Federation () para 1.10
20 Home Builders Federation () para 1.8
21 Secretary of State for Environment, Food and Rural Affairs, Post-legislative Scrutiny of the Flood and Water Management Act 2010, January 2017,
22 Defra, , March 2015
23 As above, p8. CIRIA, the Construction Industry Research and Information Association, is a member-based research and information body for the construction industry
24 Chartered Institution of Water and Environmental Management ()
25 United Utilities ()
26 For example, Wildfowl and Wetlands Trust ()
27 Institution of Civil Engineers ()
28 Bath and North East Somerset Council ()
29 Anglian Water ()
30 Defra, Post-legislative Memorandum on the Flood and Water Management Act 2010, , February 2017, p8
31 Chartered Institution of Water and Environmental Management, ? February 2017
32 Home Builders Federation ()
33 Thames Water Utilities Ltd ()
34 Wildfowl and Wetlands Trust ()
35 Wildfowl and Wetlands Trust () paras 5 -8
36 Chartered Institution of Water and Environmental Management ()
37 Defra, , March 2015
38 Chartered Institution of Water and Environmental Management ()
39 Homebuilders Federation ()
40 Wildlife Trusts () para 2.4
41 Association of Drainage Authorities () para 1.03
42 For example United Utilities () and Water UK ()
43 Water UK () para 27
44 Severn Trent () para 4.2
45 As above, para 2.2
46 Water UK ()
47 Housing and Planning Act 2016, section 171. During passage of the Bill this measure was inserted to require the Secretary of State to carry out a review of planning legislation, government planning policy and local planning policies concerning sustainable drainage in relation to the development of land in England
48 Water Management Resources ()
49 Environment, Food and Rural Affairs Committee, Second Report of Session 2016–17, Future flood prevention,
25 April 2017