Anglian Water Services Limited – Welton Microbiological Risk
Notice under regulation 28(4) of the Water Supply (Water Quality) Regulations 2016 (as amended)
Reference: ANH-2024-00003
Version Number: 2
Water undertaker as appointed under section 6 of the Water Industry Act 1991 (as amended): Anglian Water Services Limited, with registered number 02366656 (hereinafter called ‘the Company’).
Assets Affected:
- Welton WTW (Welton Reservoir) – TWEL4
- Grimsby Skegness – YGRI
Details of this Notice:
- 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 2024, which states that there is or has been a significant risk of supplying water from Welton WTW (and associated assets as applicable) that could constitute a potential danger to human health or could be unwholesome.
- 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 |
|---|---|---|
Baseline risk | Total Coliform | ANH-TWEL4-C001-TR3435 |
Baseline risk | Clostridium perfringens | ANH-TWEL4-C004A-TR3478 |
Baseline risk | Colony counts after 3 days at 22C | ANH-TWEL4-C007-TR3479 |
Baseline risk | E. coli | ANH-TWEL4-C002-TR3437 |
- 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.
Requirements:
(a) To maintain the following measures for the period specified in each case:
- Maintain enhanced bacteriological sampling and weekly large volume sampling. This must include as a minimum E. coli, coliforms, colony counts and Clostridia perfringens at a frequency and at locations as set out in the audit strategy.
Date: Ongoing for the duration of this Notice - Maintain continuous Cryptosporidium sampling from Welton WTW final water point until the site investigations have been completed. After investigations have been completed Cryptosporidium sampling should be undertaken according to frequency set out in the audit strategy.
Date: Ongoing for the duration of this Notice - Maintain continuous Cryptosporidium sampling at the second Welton WTW final water point (following installation as per step B7), until the site investigations have been completed. After investigations have been completed Cryptosporidium sampling should be undertaken according to frequency set out in the audit strategy.
Date: Ongoing for the duration of this Notice - Continue Rapid Gravity Filter (RGF) performance monitoring and backwash optimisation.
Date: Ongoing for the duration of this Notice - Notify the Drinking Water Inspectorate following a positive microbiological detection or Cryptosporidium detection from any sample taken post contact tank. Notification should be made to company liaison inspector and Enforcement mailbox via email within 24 hours of confirmation. This should be in addition and not replace any regulatory requirements for notifications.
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:
- Undertake further bacteriological sampling from Spridlington No.1 borehole to include borehole start-up time series and large volume sampling.
Date: Complete. - Review of section 9 of the Water Industry (Suppliers’ Information) Direction 2024 and the Guidance on the Notification of Events (Version 1.2) 2022, to include a review of the company’s internal triggers for notification with the relevant teams and ensure that they are appropriate, and the notification of events is conducted in a timely manner.
Date: Complete - Carry out investigations into the source of Clostridia on the Welton local delivery main.
Date: Complete - Undertake a review into potential viable options for bacteriological source identification work to help identify potential sources of contamination. Outline actions to be taken following review.
Date: Complete - Undertake a scoping exercise to identify further innovative investigations such as possible DNA sequencing. Outline actions to be taken following scoping exercise.
Date: 31 May 2025 - Relocate Welton WTW final water sampling points to downstream of the Welton and Westgate delivery main UV installations (on both streams) so that they are representative of the water being supplied to consumers.
Date: 31 July 2025 - Install continuous Cryptosporidium sampling point at the second Welton WTW final water point.
Date: 31 July 2025. - Undertake further detailed sampling investigations for bacteriological parameters into the RGFs specifically during and following backwashes from all three filters, including checks for bypassing from all RGFs during a backwash cycle.
Date: 30 June 2025. - Complete the installation of individual head loss and turbidity monitoring instruments on all three RGFs in order that an appropriate risk assessment detailing the current filter performance can be determined to meet the demands of regulation 27.
Date: 30 June 2025 - Complete the installation of the UV unit on the Westgate delivery main.
Date: 31 July 2025 - Complete the inspection of Welton North Reservoir, provide inspection reports and outline remedial works carried out.
Date: 31 July 2025 - Carry out appropriate regulation 27 risk assessment following installation of instruments in b(9). Carry out review of filter performance to determine follow up work required, if any, to return RGF to site design specification.
Date: 30 September 2025 - Carry out a review of the companies resampling processes following presumptive bacteriological detections to include a resampling response which is thorough and all encompassing, without unnecessary delays pending confirmation of the detection is conducted in a timely manner. Outline actions to be taken following review.
Date: 30 September 2025 - Complete the inspection of the downstream reservoirs at Elsham WTW and any other outstanding tanks supplying Welton works as a coordinated framework of prioritisation. Provide inspection reports and outline remedial works carried out.
Date: 30 September 2025 - Complete the inspection of Welton WTW contact tank and balancing tank. Provide inspection reports and outline remedial works carried out.
Date: 30 November 2025 - Complete the connection of the Ingham main into the Westgate main upstream of the UV process.
Date: 31 December 2025 - Continue to sample from the existing Welton WTW final water sampling point (which is upstream of the UV installations on the Welton and Westgate main and representative of the water being supplied to consumers via the Ingham main). Sampling to remain in place until the Ingham main has been connected into the Westgate main (upstream of the UV).
Date: Ongoing until completion of step b16 31 December 2025
(c) To audit whether the measures have been effective by the following means:
- Define an audit strategy to monitor the effectiveness of the measures specified in sections (a) and (b).
Date: 30 June 2025 - 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 Welton WTW, or not to so supply unless the specified conditions below are satisfied:
- Not Applicable
(e) To provide the following information in the time and manner specified below to enable monitoring of progress towards the mitigation of the risks:
- Provide a progress report annually.
Date: by 31 January each year. - Provide report evidencing completed actions b1, b2, b3 and b4 completed before serving of notice.
Date: 30 June 2025 - Provide report evidencing outcome of scoping exercise to identify further innovative investigations such as possible DNA sequencing. Provide actions to be taken following scoping exercise along with timeline.
Date: 30 June 2025 - Provide report evidencing relocation of Welton WTW final water sampling points to downstream of the Welton and Westgate delivery main UV installations (on both streams) so that they are representative of the water being supplied to consumers.
Date: 31 August 2025 - Provide report evidencing installation of continuous Cryptosporidium sampling point at the second Welton WTW final water point.
Date: 31 August 2025 - Provide report evidencing further detailed sampling investigations for bacteriological parameters into the RGFs specifically during and following backwashes from all three filters, including checks for bypassing from all RGFs during a backwash cycle.
Date: 31 July 2025 - Provide report evidencing the installation of individual head loss and turbidity monitoring instruments on all three RGFs in order that an appropriate risk assessment detailing the current filter performance can be determined to meet the demands of regulation 27.
Date: 31 July 2025 - Provide report evidencing the installation of the UV unit on the Westgate delivery main.
Date: 31 August 2025 - Provide report evidencing the inspection of Welton North Reservoir, provide inspection reports and outline remedial works carried out.
Date: 31 August 2025 - Provide report evidencing appropriate regulation 27 risk assessment following installation of instruments in b(9). Provide outcome of review of filter performance to determine follow up work required, if any, to return RGF to site design specification. Provide timeline for further actions.
Date: 31 October 2025 - Provide report evidencing review of the companies resampling processes following presumptive bacteriological detections to include a resampling response which is thorough and all encompassing, without unnecessary delays pending confirmation of the detection is conducted in a timely manner. Outline actions to be taken following review along with timeline.
Date: 31 October 2025 - Provide report evidencing the inspection of the downstream reservoirs at Elsham WTW and any other outstanding tanks supplying Welton works as a coordinated framework of prioritisation. Provide inspection reports and outline remedial works carried out.
Date: 31 October 2025 - Provide report evidencing the inspection of Welton WTW contact tank and balancing tank. Provide inspection reports and outline remedial works carried out.
Date: 31 December 2025 - Provide report evidencing the connection of the Ingham main into the Westgate main upstream of the UV process.
Date: 31 January 2026 - Provide report evidencing sampling from the existing Welton WTW final water sampling point (which is upstream of the UV installations on the Welton and Westgate main and representative of the water being supplied to consumers via the Ingham main). Sampling to remain in place until the Ingham main has been connected into the Westgate main (upstream of the UV).
Date: Ongoing until completion of step b16, 31 January 2026 - Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
Date: 31 July 2025 - Submit any revisions of the audit strategy produced under measure (c)2.
Date: Within 1 month of a revision - 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 - Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
Date: 31 January 2027
Further Details of this Notice:
4. Any product or substance used as a result of the requirements in this Notice must comply with regulation 31.
5. 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.
6. 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).
Signed
Nicholas Adjei
Deputy Chief Inspector, on behalf of the Secretary of State for Environment, Food and Rural Affairs
13 May 2025
Reference: ANH-2024-00003 v2