Flooding: frequently asked questions

Answering the most common questions around flooding.

What support is there for local authorities, and how can I keep up to date?

You can get support from the guidance documents produced by:

  • the Department for Environment, Food and Rural Affairs (Defra)
  • the Environment Agency
  • the Local Government Association (LGA)
  • the Local Government Flood Forum
  • the Construction Industry Research and Information Association (CIRIA).
  • the local authority network for drainage and flood risk management (LANDFoRM).

You can also keep up to date by being an active member of FlowNet on LGA's Knowledge Hub.

Knowledge Hub sign in page – new users will need to register

Who needs to get involved in local flood risk management?

Local government – particularly in county and unitary authorities as lead local flood authorities (LLFAs) – has a key role in local flood risk management within the context of national policies from Defra. Communities and Local Government and the Environment Agency (EA) both play strategic roles. The experience of recent, severe flooding events and the Pitt Review indicate that partnerships are essential and that local government should lead in this area.

Good flood risk management focuses on the community so it is vital that they are involved effectively to ensure the development of solutions that are tailored to the needs of the local area.

The complex nature of this area of work is such that it should involve many service areas within an individual local authority and both county and districts. Where town and parish councils exist they should be involved. It may also be essential or improve effectiveness to work in cooperation with neighbouring local authorities.

Outside local government, the emergency services, the EA, Internal Drainage Boards (IDBs), where they exist, the water and sewerage companies, the Highways Agency and Network Rail will be the other main stakeholders.

Have we got the right people to do this?

The Flood and Water Management Act places additional obligations on local authorities. The IDeA, LGA and County Surveyors Society (CSS) commissioned research to determine the scale and scope of additional resources, skills and training needed nationally to meet these obligations. The resulting report was published in July 2009. Research of local authority capacity and capability to meet the new lead role for managing local flood risk – on the LGA website

It is important that all county and unitary authorities begin to secure core skills and capacity either ‘in house' or through durable partnership arrangements. In these ways they can address the challenges at least through an ‘intelligent client' commissioning role.

To help achieve this, Defra and the Environment Agency have been working with LLFAs to improve capacity for managing local flood risk. The capacity building programme has been running since 2010 and has made a significant difference. However, local authorities will need to continue to actively recruit and train people in this area, including supporting graduate training. Specific training schemes have also been started by the EA and the LGA.

How does flood risk affect the delivery of developments?

As identified in the National Planning Policy Framework, flood risk management is now clearly identified as a major consideration in both the location and form of new developments. It thus needs to be considered at the earliest stages of the development processes.

Local plans should draw on local strategies and strategic flood risk assessments to highlight flood risk management as a key factor in shaping planning policy.

In areas of high growth, major regeneration or particular flood risk, it may be appropriate to use area action plans or other local planning documents to secure satisfactory flood risk management. These may involve sustainable drainage systems (SuDS) or surface water management infrastructure, such as a regional balancing pond.

In other areas, flood risk management and SuDS may be covered in the design and access statement or specific flood risk assessment, which may translate into delivery through planning conditions or agreements. It is implicit within this culture that flood risk management and the creation of SuDS need to interact closely with the character of a development and urban design and have a role in place making.

Provided these processes and actions are undertaken competently and at the appropriate time, they should assist the delivery of good quality development rather than impede it.

The Government has consulted on and is still developing national standards for SuDS, which, when complete, will provide the basic framework for the approval process of SuDS schemes by the SuDS Approving Body (SAB).

There is no flooding in this council area, why should we be engaged in these issues?

A council area may have significant flood risk that has not yet manifested itself in a serious incident.

It is important to recognise that flood risk may have a number of causes – rivers, sewer networks, watercourses, reservoirs or surface water runoff – and these may interact in a variety of ways.

The natural water environment is often heavily modified in urban areas. This means that the natural flood routes, which may be brought into play in more extreme rainfall events, are impeded. This in turn may mean that a particular area has high incipient flood risk.

Climate change means that we are likely to experience more extreme and more frequent rainfall events. They may be of a character that may not yet have tested the natural and engineered drainage infrastructure in an area. So all councils need to engage in both flood risk assessment and active planning processes for managing flood risk in existing developed areas and in new developments.

The complexities of flooding are such that cause and effect may not occur within the boundaries of one council. Therefore all stakeholders should be engaged in the issues. This is particularly the case in ensuring that new developments incorporate SuDS so as to prevent any impacts downstream.

Although this website focuses on flood risk, this is largely inseparable from issues of water quality. A major, growing challenge is that of diffuse pollution originating from surface water runoff sources in urban areas. The most effective mechanisms – such as SuDS – for dealing with this issue coincide with those necessary for the effective control of surface water runoff volumes.

Much of our district is in the floodplain, what do we do?

To help protect development located in the floodplain it is important to establish and understand the potential risk. This can be done by carrying out a strategic flood risk assessment (SFRA), taking into account the preliminary flood risk assessment of surface water flood risk (PFRA), which has been prepared by each Lead Local Flood Authority (LLFA) as part of a local flood risk strategy. Where it suits local circumstances, a surface water management plan (SWMP) may be an appropriate next step. The potential flood risk can then be managed through spatial planning, and appropriate measures such as avoidance, mitigation and, where necessary, resilience measures.  

Land managers and developers can play a key role in managing flooding by encouraging good site allocation, SuDS and 'green infrastructure' and mitigation measures. SuDS can help alleviate the issues of flooding through source control and by providing storage areas for the water.

Encouraging green infrastructure will also help reduce the chances of flooding further downstream by slowing down the release of water back into the watercourse. 

Existing developments and properties at high risk from flooding can use flood resilience and resistance measures to reduce the potential risks from flooding. These include retrofitting existing buildings, implementing SuDS and enhancing flood defences. 

An emergency plan and raising awareness of the potential risk in the local community can help mitigate the effects of flooding.  

Why do we need sustainable drainage systems (SuDS) in low-risk areas?

SuDS will become a legal requirement once the relevant section of the Flood and Water Management Act (2010) is enacted. This may in April or October 2013. Once fully implemented, any development where more than one property is drained to the public sewer must provide SuDS in accordance with national standards. The LLFA, as SuDS Approving Body, will be responsible for approving the SuDS design, adopting the scheme once built and then maintaining it. SuDS approval will be a parallel process to planning, but SuDS approval must be obtained before development can commence. The SAB will also be responsible for approving connection to the public sewerage network, as the automatic right to connect will be removed.

SuDS are encouraged in low-risk areas because they can manage the impact of flooding further downstream in the catchment area.   

SuDS can deliver multiple benefits, not just managing flood risk. They can also help improve the quality of water entering the watercourse and significantly contribute to a development because of their amenity, biodiversity and social benefits. They can help create attractive places, which can increase the value of properties and encourage people to use the outside space. 

What role do highways play in local flood risk management?

Highways and their associated infrastructure play a key role in local flood risk management. It is important that existing gulley pots, pipes and channels are effectively maintained and that flood risk management principles are incorporated into new design.

Highways represent a significant proportion of the impermeable area which creates surface water runoff in urban areas. In new developments, they are integral in the design and delivery of SuDS. For example, slow conveyance through porous paving or filter strips can help attenuate the flow. The volume of runoff can be reduced by using structures which maximise infiltration, such as swales, and detention basins.

As well as ensuring that highway drainage infrastructure does not contribute to local flood risk, there is also a growing requirement to ensure that water quality is effectively managed. The surface water runoff component from roads carries the greatest proportion of pollutants. These can be retained and removed within highway SuDS, rather than being washed away into gullies and piped drains that find their way into watercourses.

In certain circumstances roads can be used for the conveyance of water in extreme events. These roads need to be designed for conveyance and require effective planning and flood warning.   

Are sustainable drainage systems (SuDS) going to increase the cost of development?

This is very site and case specific. If SuDS are considered at an early stage there should be little additional cost. Some evidence suggests that, if properly planned and designed, the overall capital construction cost of SuDS can be cheaper. However, the design process itself may be slightly more expensive.

The maintenance of SuDS again will correspond to the specific site and SuDS components used. In some cases this will include litter picking, mowing the lawn and silt management. In others, the maintenance tasks may be more involved.

When thinking about costs, the benefits of SuDS over and above traditional drainage should also be considered. The benefits include flood risk management, pollution control and delivering better places to live. Some research suggests that SuDS components that are landscaped can add around 10 per cent to the value of housing that overlooks them.

Is there enough space in developments to deliver sustainable drainage systems (SuDS)?

If SuDS are considered, planned and designed before, or at the same time as, the form and layout for development – in the context of a design statement and place making – they can easily be incorporated.

Even after this, SuDS can be included in high-density developments with good design.

SuDS include a number of features that can either be used where there is little space, for example, green roofs, communal rainwater harvesting, attenuation tanks. They can provide additional benefits, for example, permeable paving. Some components can also make dual use of public open space, such as detention basins.