Current improvement programmes

Notice of Regulation: Barcombe Mills Treatment Works



South East Water Limited: Barcombe Mills Treatment Works

Reference: SEW-2018-00004

Water undertaker as appointed under section 6 of the Water Industry Act 1991 (as amended): South East Water Limited, with registered number 02679874 (hereinafter called ‘the Company’).

Assets affected:

T030 Barcombe Mills No. 1 Works
T031 Barcombe Mills No. 2 Works
Z047 Barcombe Water Supply Zone

  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 1 September 2017, which states that there is or has been a significant risk of supplying water from Barcombe Mills 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:
    • The duty to ensure wholesomeness at the consumer’s tap as defined by Regulation 4 and the other requirements of the Water Supply (Water Quality) Regulations 2016 (as amended).
    • Risk of failure to meet the requirements of Regulation 26.
    • Manganese
    • Turbidity
    • Iron
    • Microbiological indicators
    • Cryptosporidium

  1. The Company are required to satisfy the following:


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

  1. Optimisation of all existing treatment processes, particularly particulate removal stages to comply with Badenoch and Bouchier recommendations1.
    Date: Ongoing for the duration of this notice
  2. Implement a documented strategy for managing raw water quality, including monitoring and managing algae in the river and the raw water storage reservoir, to ensure that treatment processes important for particulate removal are not compromised and forced to operate outside documented operational limits (as specified in ii above).
    Date: Ongoing for the duration of this notice
  3. Continuous final water monitoring for Cryptosporidium.
    Date: Ongoing for the duration of this notice
  4. Continuous online turbidity monitoring upstream of UV treatment and chlorine contact, with appropriate alarms and failsafe shutdown on both treatment streams, as appropriate.
    Date: Ongoing for the duration of this notice
  5. Continuously review all critical control points and mitigation measures for the duration of this notice with a view to updating the notice with additional measures where required.
    Date: Ongoing for the duration of this notice
  6. Ensure that the works operators have an adequate recourse to scientific water quality and management support in the event of a deterioration in works’ performance.
    Date: Ongoing for the duration of this notice
  7. Comply with the requirements of regulation 35(6) and the Water Industry (Suppliers’ Information) Direction 2017, to notify the Inspectorate, Public Health England and local authorities in response to events where there is a potential risk to public health from water supplied from Barcombe Mills Works.
    Date: Ongoing for the duration of this notice

1 Cryptosporidium in Water Supplies, Reports of the Groups of Experts published in 1990, 1995 and 1998

(b) to review, revise and make operational the following measures by the dates specified below:

Risk Assessment and Gap Analysis

  1. Establish the baseline water quality performance for the Barcombe Mills No.1 and No.2 Works based on the design criteria for the works, maximum flows and loading rates for each process and put procedures in place to ensure that the works is operated within the established criteria, with appropriate alarms and shutdown response where required.
    Date: Complete
  2. Complete a detailed risk assessment of Barcombe Mills No.1 and No.2 Works and the associated supply system, involving a full review of hazards, points of failure and critical control points and existing controls (adopting a HazRev approach), and identify improvement measures.
    Date: Complete

Raw Water Storage

  1. Complete reactive dredging of the raw water reservoir to remove accumulated sludge and implement a routine dredging assessment and dredging as required.
    Date: Complete

Supernatant Return (from sludge processing)

  1. Move outfall of supernatant return further away from treatment works intake.
    Date: Complete
  2. Install appropriate metering, monitoring, sampling arrangements and laboratory analysis to adequately risk assess the supernatant return to the head of Barcombe Mills works’ raw water reservoir.
    Date: Complete
  3. Install online continuous monitoring for manganese at a suitable point or points, with appropriate alarms, to monitor the effectiveness of manganese removal in No.1 and No.2 treatment streams.
    Date: Complete

Chlorine Contact Tanks

  1. Undertake an internal inspection of contact tank No.2 at works No.2 and complete necessary cleaning.
    Date: Complete
  2. Complete a critical review of the operational hazards associated with Barcombe Treatment Works Contact Tanks, with specific consideration given to all structural defects, in particular those identified during the internal inspection carried out on 25 September 2019.
    Date: Complete
  3. Complete a review to identify options to address structural defects identified,
    Date: Complete
  4. Commence the chosen option of the optioneering review.
    Date: Complete
  5. Complete contact tank remedial work or suitable alternative solutions and undertake suitable validation monitoring.
    Date: 31 December 2021
  6. Confirm and make changes as appropriate to establish that the Barcombe Mills export to Arlington Works does not compromise disinfection or disinfection monitoring at Arlington contact tank.
    Date: Complete
  7. Ensure sufficient metering, monitors and controls are in place at Barcombe Mills Works to demonstrate disinfection conditions are maintained in the contact tank under all operating conditions. Including flow alterations between Barcombe Mills Works 1 and 2 and also during water transfers from Arlington Works and Cow Wish Works to Barcombe Mills.
    Date: Complete

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

  1. Continuous sampling for Cryptosporidium oocysts at an appropriate sampling point or points representative of treated water supplied from No.1 and No.2 works.
    Date: Ongoing and for duration of the notice.
  2. Enhanced operational sampling, for laboratory analysis, for iron, manganese, pH and turbidity in works’ No.1 and No.2 treated waters.
    Date: Ongoing and for duration of the notice.
  3. Continuous demonstration of contact tank inlet turbidity (all inputs), Ct value, pH, retention time, and satisfactory sample analysis.
    Date: Ongoing and for duration of the notice.

(d) not to supply water for regulation 4(1) purposes from Barcombe Mills Works No.1 and Barcombe Mills Works No.2 unless the conditions specified below are satisfied:

  1. Not Applicable

(e) to provide the following information in the time and manner specified belowto 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:
    • To confirm status of steps (b)1 to 7.
      Date: Ongoing
  2. Provide a summary report from the optioneering review in (b)9. Confirming the actions and time scale required for Barcombe contact tank 2.
    Date: Complete
  3. Confirm completion of works determined in (b)11. and confirm validation procedure.
    Date: 31 January 2022
  4. Submit a report in the event that any completed measure of this Notice needs to be altered in any way for any reason.
    Date: Ongoing for the duration of this notice
  5. Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off. To include the following details based on twelve months data.
    Date: 28 February 2023
    • An assessment of risks to water quality associated with the processing and importing of sludge from offsite at the Barcombe Mills No.1 and No.2. Works
    • Assessment of disinfection and the impact on disinfection and the ability to meet the requirements of Regulation 26 when the site is importing water from Cow Wish Bottom and Arlington Works.

  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).

Laura Moss
Deputy Chief Inspector, on behalf of the Secretary of State for Environment, Food and Rural Affairs
16 June 2021
Reference: SEW-2018-00004
Version 4