Thames Water has gone out to tender with a major AMP8 contract for sludge holding tanks and roofs - the procurement covers the supply, installation and commissioning of new sludge tanks, digesters, other associated tanks, roofs and related items at various wastewater treatment sites.

Photo: aerial view of Mogden Sewage Treatment Works 

The water company's objectives are as follows:

• Compliance: Ensure compliance with legislation, improve the environmental impact of the STW and provide infrastructure which is fit for purpose.
• Commercial Value: Optimise the material and delivery solution to maximise commercial efficiencies for Thames Water
• Futureproofing: Implement a framework which enables Thames Water to be able to secure the capacity it requires for future programmes of works
• Procurement Approach: A competitive tender process will be undertaken to appoint a supplier(s) capable of delivering the required scope. The strategy favours a supplier who can streamline delivery, ensure consistency, and maximise commercial and operational benefits.
• Procurement Timeline Considerations: The procurement timeline is currently under review due to strategic and regulatory reassessments at certain sites. Specifically:

A study evaluating the requirements to meet Environment Agency Industrial Emissions Directive (IED) requirements is currently ongoing, with outcomes expected later in the year. Thames Water said the findings will inform final scope and procurement readiness.

Expected outcomes

• Improved asset reliability and operational performance
• Enhanced alignment with environmental and regulatory objectives
• Commercial efficiencies through strategic sourcing and standardisation

The contract is being tendered in the following Lots:

Lot 1. Sludge Holding Tanks (including digesters and other associated tanks) - supply and Installation

The procurement relates to the supply and commissioning support of Sludge tanks, Digesters and Roofs and associated items across potential multiple wastewater treatment sites.

Lot 2. Sludge Holding Tanks (including Digesters and other associated Tanks) (CDM Responsibilities)

This procurement relates to the supply and commissioning support of Sludge tanks, Digesters and Roofs and associated items across potential multiple wastewater treatment sites whilst acting as the responsible CDM representative at the location.

Lot 3. Sludge Holding Tank Roofs (including Digesters)

This procurement relates to the supply and commissioning support of roofs for the fitting to Sludge tanks, Digesters and associated items across potential multiple wastewater treatment sites

The water company is looking to appoint a number of supplers to the framework. Mini-competitions will be held under the framework once requirements are defined.

The procurement will follow a Competitive Flexible Procedure in line with the Procurement Act 2023 and the process will include multiple stages, with opportunities for clarification, negotiation, and refinement of award criteria before final contract award.

Stage 1: Tender Notice Publication

Release of Contract Notice outline the scope of requirements, procurement stages, and timelines

Stage 2: Pre-Specific Questionnaire (PSQ)

• PSQ Publication
• Supplier Response: Suppliers will complete and submit the PSQ by the stated deadline Clarification Period: A defined window will allow suppliers to raise queries and Thames Water to provide clarifications
• Evaluation: PSQ responses will be assessed on a pass/fail and weighted basis against mandatory criteria
• Outcome: Successful suppliers will be shortlisted and invited to the next stage

Stage 3: Preliminary Tender Submission

• Issue of Documents: Shortlisted suppliers will receive the full information pack
• Clarification: Suppliers submit any clarification questions to the tender. TW will answer
• Submissions: Suppliers submit bid submissions (technical and commercial proposals)
• Clarification and Questions: TW submit clarifications and questions to the supplier responses
• Evaluation: Submissions are assessed against published criteria

Stage 4: Negotiation Stage

• Shortlisted suppliers will receive invitations to negotiate and further information about the process
• Negotiation and Refinement: Negotiations with suppliers to refine solutions and optimise value
• Updated Submissions: Suppliers to submit revised bids following negotiation rounds

Stage 5: Final Evaluation and Selection

• Evaluation: Final submissions are evaluated against weighted criteria
• Stage 6: Contract Award
• Notification: Successful and unsuccessful suppliers will be informed in writing
• Standstill Period: A mandatory standstill period will apply before contract signature
• Contract Execution: Following standstill, the contract will be awarded and signed

Deadline for submission of enquiries about the tender is 5:00pm on 15 December 2025. The deadline for asking for access to the Pre-Specific Questionnaire (PSQ) and submitting the PSQ is 10.00 am on 22 December 2025.

Estimated start and end contract dates are currently 1 June 2026 to 31 May 2034 and estimated award decision date is currently 18 May 2026.

To gain access to the PSQ documents, interested suppliers are asked to fill out their details on a short online form and provide their company name, company address (the address of what would be the contracting company entity) and contact details of two people from their organisation with whom Thames Water can correspond. Click here to access the form.