South Staffordshire Water Plc – Sawston Mill – PFOS

Notice under regulation 28(4) of the Water Supply (Water Quality) Regulations 2016 (as amended)

Reference: CAM-2022-00001

Version Number: 5

Water undertaker as appointed under section 6 of the Water Industry Act 1991 (as amended): South Staffordshire Water Plc, with registered number 02662742 (hereinafter called ‘the Company’).

Assets Affected:

  • T086 – Sawston Mill (Duxford Airfield)
  • Bluntisham Supply System
  • Cambridge City North Supply System
  • Cambridge City South Supply System
  • Cambridge North Supply System
  • Cambridge South Supply System
  • Cambs Rural Supply System
  • Coton Supply System
  • Sawston Supply System

Details of this Notice:

  1. The Drinking Water Inspectorate (‘the Inspectorate’) has received a regulation 28(1) report of the Water Supply (Water Quality) Regulations 2016 (as amended) (‘the Regulations’) from the Company dated 01 October 2021, which states that there is or has been a significant risk of supplying water from Sawston Mill (Duxford Airfield) treatment works (and associated assets as applicable) that could constitute a potential danger to human health or could be unwholesome.
  2. Consequently, this Notice is served on the Company by the Inspectorate on behalf of the Secretary of State, under regulation 28(4) for the assets listed above, for risks associated with:

Description of Risk

Hazard/ Hazardous Event/ Parameter

Hazard I D

Prescence of per- and poly fluoroalkyl (PFAS) substances in the source water.

Perfluorooctane Sulphonate (PFOS)


Table 1: Table of the hazards, hazardous events, and/or parameters covered by this Notice, including the Hazard I D numbers and the description of risks.
  1. The Company are required to satisfy the following requirements.

The date given is that until or by which the requirements must be maintained or satisfied, as appropriate.


(a) To maintain the following measures for the period specified in each case:

  1. Monitor for PFAS substances in the source water, at a frequency of once per week when the Duxford Airfield borehole is in operation.
    Date: Ongoing for the duration of this notice

(b) To review, revise or make operational the following measures, by the dates specified in each case:

  1. Design a solution to mitigate the risks from PFAS substances in the source water.
    Date: Complete
  2. Implement the solution designed in step (b)1. This is to include construction, installation, and commissioning into supply.
    Date: 31 May 2024
  3. Review and revise the regulation 27 risk assessments to include;
    • the use of firefighting foam used between September 2008 and March 2022 and potential risks to the aquifer;
    • the use of new firefighting foam and any new risks this could pose;
    • risks associated with unknown peak concentrations of PFOS.
      Date: 30 June 2024

(c) To audit whether the measures have been effective by the following means:

  1. Define an audit strategy to monitor the effectiveness of the measures specified in sections (a) and (b).
    Date: Complete
  2. Implement, and keep under continuous review, the audit strategy defined in measure (c)1.
    Date: Following completion of measure (c)1. onwards.

(d) Not to supply water for regulation 4(1) purposes from Sawston Mill (Duxford Airfield), or not to so supply unless the specified conditions below are satisfied:

  1. The concentrations of PFAS substances in the source water are controlled appropriately, to ensure unwholesome water cannot be supplied.
    Date: Ongoing for the duration of this notice

(e) To provide the following information in the time and manner specified below to enable monitoring of progress towards the mitigation of the risks:

  1. Provide a progress report annually.
    Date: by 31 January each year.
  2. Provide a report detailing the chosen long-term solution, delivered under measure (b)1.
    Date: Complete
  3. Provide a report confirming completion of the long-term solution under measure (b)2. To include construction, installation, and commissioning into supply.
    Date: 30 June 2024
  4. Submit revised risk assessments under regulation 28(1) following completion of measure (b)3.
    Date: 31 July 2024
  5. Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
    Date: Complete
  6. Submit any revisions of the audit strategy produced under measure (c)2.
    Date: Within 1 month of a revision
  7. Submit a report in the event that any completed measures of this Notice need to be altered in any way, for any reason.
    Date: Ongoing for the duration of this Notice
  8. Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
    Date: 30 June 2025

Further Details of this Notice:

  1. Any product or substance used as a result of the requirements in this Notice must comply with regulation 31.
  2. Under regulation 28(6) the Inspectorate, on behalf of the Secretary of State, may by notice served on the Company, revoke or vary this Notice.
  3. Failure by the Company to comply with this Notice may result in enforcement proceedings under section 18 of the Water Industry Act 1991 (as amended).
  4. Contravention of a regulation 28(4)(d) requirement is an offence under regulation 33(1). If guilty of such an offence, the Company is liable on summary conviction, or on conviction on indictment, to a fine. Under regulation 33(2) it is a defence for the Company to show that it took all reasonable steps and exercised all due diligence to avoid the commission of the offence.


Nicholas Adjei
Deputy Chief Inspector, on behalf of the Secretary of State for Environment, Food and Rural Affairs
22 February 2024
Reference: CAM-2022-00001 v5

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