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Designing the solution

At this stage, you’ll have received a budget estimate from us and should have modified your scheme where possible to minimise any effect it has on our pipes and equipment. If you now want us to consider diverting any of our mains and/or sewers, you’ll need to request a formal detailed estimate. This is known as C4 under the New Roads & Streetworks Act 1991.

If you’re requesting this, you’ll need to be sure that this is your complete and final scheme, which you won’t be revising at a later date. You’ll also need to pay the design fee we provided to you at stage C3.

Please make sure you contact us at an early stage and tell us about your full scheme, rather than part of it. You should note that we’ll provide an estimate for only one scheme, rather than a range of options.

Your request needs to be set out in a letter. You can either email this to the address from which you received your C3 budget estimate or send it to us at:

Thames Water Strategic Partnering
Clearwater Court
Vastern Road

Your letter will need to tell us:

  • The client – i.e. the qualifying authority with whom we’ll have a financial relationship.
  • The consultant / agent / contractor (as applicable).
  • A brief, general summary of your scheme.
  • An indicative programme for your works.
  • The source and proportion of funding from highways (or other) budget.

We’ll also need drawings showing your final detailed design, in .pdf and CAD formats, so that we can start our own detailed design work.

In addition, we’ll require your health and safety documentation, so that our contractors can produce their own health and safety plan. This consists of your F10 Health & Safety at Work Act Notification of Project to the Health & Safety Executive, and your contractors’ draft Health & Safety at Work Act Health & Safety Plan.

We’ll require a letter of appointment if our financial relationship will be with another organisation, and not directly with the qualifying authority.

You’ll also need to provide the same information if you’re requesting an estimate under the Transport & Works Act 1992, which covers rail schemes.

If you’ve not provided enough detail for us to confidently give you a firm estimate, we’ll provide you with an ‘enhanced C3’ estimate. We’ll let you know the information we need before we are able to give you a C4 estimate.

What we’ll do

Assuming you’ve provided us with all the information set out above, we’ll start producing contract documents and drawings to show our contractors the work that will be done at your site.

Alternatively, if there’s no need to divert our pipes, we’ll provide a protection letter, setting out how to avoid damaging our equipment during your work. We may also direct you to another team or request further details of your scheme.

Our timescales

We’ll acknowledge receipt within seven days.

For single diversions, we’ll provide a detailed estimate within five weeks.

For multiple diversions, we’ll give you an anticipated date by which we’ll provide you with our estimate. Again, we’ll give you this date within five weeks of your request.

More complex schemes are likely to take longer. We’ll consider the entire project scope and its effect on our water and/or waste networks.

Costs and payment

Before progressing to the next stage, you’ll need to pay the balance between the C4 detailed estimate and the design fee already paid, taking into account any cost-sharing arrangements which you claim.

In the case of an ‘enhanced C3’ estimate, we’ll notify you of any additional design fee payable should there be insufficient funding to progress to the C4 detailed stage.

Alternatively, you can place an order with us to secure the works, but in this case the costs incurred will be fully rechargeable.