Undertakings: Southern Water – SES Bulk Imports



  1. is satisfied that Southern Water Services Limited “the Company” in supplying water in water supply zones receiving BULK IMPORTS of water orginating from Bough Beech Water Treatment Works and Outwood Water Supply Zoneoperated by Sutton and East Surrey Water PLC (trading as SES Water) which may be at risk of exceeding the standard for metaldehyde. This means that the Company is likely to contravene its duty in respect of supplying water which meets the Regulations under Section 68(1)(a) of the Water Industry Act 1991 and meets the requirement set in regulation 4(2)(c) of the Water Supply (Water Quality) Regulations 2016 (as amended).
  2. notes that Southern Water Services Limited has on 21 July 2021 given an undertaking (DWI Ref No: SRN-2021-00002) under section 19(1)(b)of the Water Industry Act 1991 to take the following steps by the dates shown:

Steps to be taken


Date: Ongoing for the duration of the Undertaking.

  1. For the period of the undertaking, implement an enhanced monitoring strategy for metaldehyde in the identified supply zones to supplement the regulatory programme.
  2. If the concentration in any water sample exceeds the maximum concentration agreed with Public Health England the Company will take all reasonable measures in consultation with local health professionals to minimise the impact on customers.
  3. Report exceedances of the 0.1 μg/l standard to the Inspectorate in accordance with the current monthly exception reporting.


Continue to regularly liaise with the companies providing the bulk supplies to monitor progress with the measures being taken to secure compliance with the metaldehyde standard at their treatment works.
Date: Ongoing as necessary, for the duration of this Undertaking


To continually assess the risk of metaldehyde and total pesticides as a hazard in the supply systems associated with the identified treatment works which provide the bulk supplies of water to the Company and provide updates of the Regulation 28 risk assessment reports as appropriate.
Date: Ongoing for the duration of this Undertaking


Provide DWI with reports on progress with carrying out the steps set out in the undertaking.
Date: Annually for the duration of the Undertaking. Reporting periods are Jan – Dec. Reports to be submitted by 31 Jan each year that the Undertaking is in place.

Reports to include at least the following details:

  1. Metaldehyde monitoring data for the zones listed in the Annex to this schedule;
  2. Details of contacts made with the supplying water company concerning the actions that company is undertaking to address the risk of metaldehyde in the water supplied.
  3. Any other relevant information.


Provide a final report to DWI on the outcome of the activities undertaken, including by the incumbent water companies, the solutions implemented, and the conclusions drawn from other work carried out.
Include, as evidence for closure for this scheme, appropriate documentation to confirm that the actions set out in this schedule of work have been completed and the extent to which the required outcomes have been achieved.
Date: When there is sufficient evidence of suitable mitigation of the risk (i.e. 3 years samples below 0.1ug/l and evidence of stable or decreasing raw water trends) or by the 31st March 2025.

  1. is satisfied that Southern Water Services Limited has given and is complying with an undertaking to take all such steps as appear to the Secretary of State for the time being to be appropriate to secure or facilitate compliance with the requirement of regulation 4(2)(c) of the Water Supply (Water Quality) Regulations 2016 (as amended)..

Authorised by the Secretary of State to sign in that behalf:
Laura Moss
Deputy Chief Inspector
Drinking Water Inspectorate
DWI Ref No: SRN-2021-00002
Version 1
21 July 2021

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