Notice of Regulation: Hanningfield Water Treatment Works




Hanningfield WTW T002

Legal Instrument Database Reference number: LI/ESK/2018/00001


  1. has on 18 October 2016 received a report from Essex and Suffolk Water (the “Company”) dated 30 July 2015 (the “Report”) which states that there is or has been a significant risk of supplying water from Hanningfield WTW that could constitute a potential danger to human health.
  2. GIVES NOTICE to the Company under regulation 28(4) of the Water Supply (Water Quality) Regulations 2016 (as amended) that it must satisfy the following requirements:

For risks associated with:

  • Cryptosporidium
  • Disinfection (pre conditioning)
  • Turbidity


(a) to maintain the following measure[s] for the period specified [in each case]

  1. Adequately maintain and operate existing treatment processes
    Date: Ongoing
  2. Respond to positive detections of Cryptosporidium in the final water supplied to consumers as per the company’s procedures and ensure public health is not compromised
    Date: Ongoing
  3. Respond to elevated online water quality alarms to prevent deterioration of final water supplied to consumers.
    Date: Ongoing

(b) to [review, revise and/or make operational] the following measures, by the date specified below:

General site

  1. Produce a site specific algal management plan comprising short, medium and long term actions
    Date: Jan 2020


  1. Review water quality monitoring and control of the clarification process to ensure it is fit for purpose and meeting the design specification
    Date: May 2019
  2. Undertake a scientific review of alternative coagulants and flocculants to ensure effective products can be utilised for the raw water condition
    Date: Jan 2020
  3. Conduct a study into the applied dosing using results from the bench trials once the chemical review has been concluded
    Date: Jun 2020


  1. To review the design and operation of the rapid gravity filters with a view to improving operational performance and reducing outlet turbidity to comply with recognised industry good practises and recommendations
    Date: May 2019
  2. Install individual turbidity monitors on the outlet of each filter so that performance can be assessed and monitored
    Date: Mar 2019
  3. Ensure individual turbidity monitors are connected to the telemetry system and appropriate water quality alarms are installed to ensure the pre disinfection and wholesomeness requirements are maintained
    Date: May 2019
  4. Review backwash performance and triggers
    Date: Jul 2019

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

  1. Carry out continuous Cryptosporidium sampling of the final water at Hanningfield WTW company to specifiy adequate frequency
    Date: Ongoing
  2. Undertake a sampling programme to assess and verify the quality of the water from the clarification process and comparative assessment of instruments
    Date: Jan 2020
  3. Review clarifier and filter performance to assess suitability of coagulants and dosing levels demonstrate appropriate coagulant and flocculant combinations are being used.
    Date: Ongoing
  4. Carry out continuous online monitoring of turbidity at the outlet of the clarification process and ensure alarms are escalated and investigated appropriately to mitigate and action water quality risks
    Date: Ongoing
  5. Ensure the site operating procedures are updated with any new plant and equipment
    Date: Ongoing
  6. Use individual turbidity trending from filters to optimise filter performance and maintain disinfection and wholesomeness
    Date: Ongoing

(d) N/A

(e) to provide the following information in the time and manner specified below to enable monitoring of progress towards the mitigation of the risk of supplying water that would constitute a potential danger to human health:

  1. Provide a progress report annually by 31 January and against the following milestones:
    • Provide evidence of bench trials carried out on alternative clarification chemicals
      Date: Jan 2020
    • Provide evidence of the installation of individual turbidity monitors on the filters and associated water quality alarms
      Date: May 2019
    • Provide evidence of the review of clarification dosing chemicals
      Date: Jun 2020
  2. Review the risk assessment for Hanningfield WTW as required by regulation 27(3) and subsequently submit a revised regulation 28 report accompanied by a signed board level declaration.
    Date: Oct 2019
  3. Submit a satisfactory completion report
    Date: Jun 2021

Failure by the Company to comply with this Notice may result in enforcement proceedings under section 18 of the Act.

Signed by authority of the Secretary of State
Milo Purcell
Deputy Chief Inspector
13 November 2018
DWI ref: LI/ESK/2018/00001
Version 1

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