Surrey S19 Flood Investigations

Section 19 - Local authorities investigations

As part of the duties under the Flood and Water Management Act 2010, Lead Local Flood Authorities (LLFA) are required to investigate flooding incidents. Section 19 (S19) came into force in April 2011 and states that:

  1. On becoming aware of a flood in its area, a lead local flood authority must, to the extent that it considers it necessary or appropriate, investigate:
    (a) which risk management authorities have relevant flood risk management functions, and
    (b) whether each of those risk management authorities has exercised, or is proposing to exercise, those functions in response to the flood.
  2. Where an authority carries out an investigation under subsection (1) it must:
    (a) publish the results of its investigation, and
    (b) notify any relevant risk management authorities.

The above Act does not compel the Lead Local Flood Authority to identify all the causes and parties responsible for the flooding. It only requires to identify the risk management authorities (RMAs) with relevant flood risk management functions. In most cases, investigations will uncover both criteria. Where it doesn't, the County will work with all parties to try and resolve the issues.

Not all floods will be investigated. The following preliminary triggers were established by the Surrey Flood Risk Partnership Board (SFRPB).

  1. A flood occurs and is present for some time with no known source.
  2. Ten or more properties in a catchment experience internal flooding. *
  3. A single property experiences repeat internal flooding within five years of the initial flooding.
  4. Ten or more commercial properties experience internal flooding or a single commercial property greater than 500m2 experiences internal flooding.
  5. One or more items of critical national infrastructure experience flooding.
  6. A transport link is impassable for a number of hours.
    a. Two hours - Major rail link, Motorway, Trunk road, Surrey Priority Networks 1 and 2
    b. Six hours – Minor rail link, Surrey Priority Network 3
    c. Ten hours – Surrey Priority Networks 4a and 4b and all other locations
    7. The SFRPB consider that an investigation is required.
  7. The SFRPB consider that an investigation is required.

*Internal flooding refers to the habitable part of the dwelling and excludes garages, outhouses and gardens
^These criteria may be altered by the SFRPB if circumstances come to light requiring change.

Please note that these triggers are used as a guide only and do not compel the LLFA to complete a detailed Section 19 investigation. The LLFA may ultimately use its discretion to determine whether it is proportionate and appropriate to launch an investigation into a flood event. If the decision is taken to launch a Section 19 investigation, it will as a minimum consist of stating which RMAs had relevant risk management functions and whether each of those RMAs exercised, or proposes to exercise, those functions. Any additional information will be discretionary.

A "frequently asked questions" document has been produced to address the more common queries relating to S19 Flood Investigations.

S19 Flood investigation frequently asked questions (PDF)

Any other queries can be directed to:

All completed S19 Flood Investigation reports, along with their supporting maps are available below:


Winter 2013 to 2014 flood event

23 June 2016, Hengest Avenue flood event

Epsom and Ewell

Winter 2013 to 2014 flood event

July 2021 flood event


Winter 2013 to 2014 flood event

Mole Valley

Winter 2013 to 2014 flood event

Reigate and Banstead

Winter 2013 to 2014 flood event

12 July 2021 Nork and Tattenhams flood event


Winter 2013 to 2014 flood event


Winter 2013 to 2014 flood event

January 2021

Surrey Heath

Winter 2013 to 2014 flood event


Winter 2013 to 2014 flood event

07 June 2016 flood event


Winter 2013 to 2014 flood event


Winter 2013 to 2014 flood event

11 May 2016 flood event

16 September 2016 flood event

Further information:

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