NAV setup

In order to make your application to Ofwat for the new appointment, you’ll need some information from us as the incumbent water and/or sewerage company. The information below describes how you can request this. If you’re looking to make a bulk connection with our network(s), we can also help you set up the bulk agreement(s), arrange for any site-work and set you up as our customer.

A site will be eligible for applying for a new appointment and variation if it is:

  • unserved;
  • for a large user; or
  • given consent by the incumbent water and/or sewerage company.

Due to the time we need to process applications, we can guarantee issuing quotes under our 2019/20 charging arrangements for applications received by the following dates:

  • 19 February 2020 for sites with more than 500 properties
  • 4 March 2020 for sites less than 500 properties

We can guarantee these dates for fully completed applications where no further information is required. For clarity, any requests for an asset payment calculation, must be submitted in full before these dates also. Any applications or requests submitted after the above dates will be provided under our 2020/21 charging arrangements.

If work has not started in your area and feel that our 2020/21 charging arrangements are more favourable to your scheme, you can request a requote after 31 March 2020. Please note that a requote fee will be applicable.

NAV market interfaces and application timeline

You can apply for services using the NAV portal or the forms below. Please see our User Guide if you need help navigating into the portal. 

NAV portal login

For more information on how to apply for a new appointment or variation please see the Ofwat guidance.


The services listed below reflect Ofwat’s guidance and these can be requested all at once, or one by one, using these forms.

Tip: Download and save the relevant form, adding the name of the site to the filename. The form can be completed digitally, so there’s no need to print and scan paper copies. Also, the same form can be submitted for each service request, so you don’t have to fill out the same fields every time. If you'd like to discuss your form prior to submitting it, please contact Wholesale Market Services here.

  1. You complete and submit sections A, B and C) i) of the relevant form
  2. We check our records to determine the site status:
    1. We acknowledge receipt of your request (within one business day)
    2. Our agents conduct a desktop assessment, looking up the site coordinates against our network plans and account management systems
  3. We’ll respond with our assessment within 15 business days
  4. If the site is considered served, we can discuss your options for adjusting the site boundary or requesting consent

If a single customer uses more than 50 million litres per year (or 250 million litres per year in Wales), it qualifies as a Large User. Ofwat’s Guidance gives further details.
Please let us know that you're applying under this basis, using sections A, B and C) ii) of the relevant form.

We’ll consider requests for consent on a case-by-case basis, and the final decision is made by the Thames Water Board. We’ll charge a Consent Fee, which is determined with regard to the affected customers and network assets. In all cases, including where a consent is denied, administrative charges may apply. We’ll respond to your request within 10 business days and set out the next steps.

  1. You complete and submit sections A, B, C) iii) and D) of the relevant form.
  2. We review your submission, and let you know within 10 business days whether more information is required, and any instructions for providing it.
  3. Once we have all the information we need, we make a preliminary assessment of the affected assets and customers. We’ll share this with you within 15 business days, with instructions for progressing the consent request. This includes next steps, timescales and charges, including an estimated Consent Fee.
  4. You give written confirmation that you accept the terms and charges for progressing the consent request.
  5. We calculate a Consent Fee based on the information provided and submit a paper to our Board, proposing you being appointed to the relevant site, subject to certain terms and fees.
  6. We notify you of the outcome and, if our Board has approved to provide consent, share our offer to you, including any relevant terms and Consent Fee.
  7. You let us know if you accept these terms and Consent Fee.
  8. We draft the terms of the consent into the relevant Bulk Supply/Discharge Agreement, including the Consent Fee, and provide a letter of consent for you to present to Ofwat.

In order to apply to Ofwat for the site to become a NAV, you’ll need certain information from us about the site and how any water / wastewater services will be supplied from us to you. We need to make sure that the technical solution being proposed will meet your site’s needs. You’ll need to account for any charges associated with setting up the connection and getting bulk services from us. This involves us proposing a technical solution and providing a budget estimate for any connection work, as well as price and non-price terms for bulk services.

  1. To request this information, you complete and submit sections A, B and D of the relevant form.
  2. We’ll review and acknowledge your request, letting you know if any more information is required or if we think it’ll take longer than 20 business days to provide a response.
  3. We’ll conduct a desktop assessment of the site’s requirement and the surrounding network. Our engineers create a technical solution to meet your needs and produce a budget estimate for providing the connection(s) to your site.
  4. We’ll respond to your request for network information within 20 business days of receiving complete information.

We may request you to provide further information about the site, and if dealing directly with our engineers, please copy us in on any correspondence.

In order for Ofwat to grant the site to become a NAV, the Drinking Water Inspectorate (DWI) will need to have received a satisfactory risk assessment. You can ask us to provide certain information for this, such as drinking water safety plans.

  1. You complete and submit sections A, B and E of the water bulk supply form.
  2. We acknowledge receipt of your request within one business day.
  3. We collate the relevant risk assessment information for the site and respond within 15 business days.

We may ask you to provide further information about the site, and if dealing directly with our teams in Water Quality, please copy us in on any correspondence.

Once your application with Ofwat has started, or if you request it sooner, we’ll start drafting a Bulk Supply Agreement (for water) and/or a Bulk Discharge Agreement (for wastewater), based on the information you’ve provided.

The terms of this agreement include the technical supply/discharge details, the duties of either party, the associated charges and some form of guarantee or deposit arrangement.

  1. You complete and submit section F of the water bulk supply form and/or section E of the wastewater bulk discharge form. This provides us with the information we require in order to draft a contract based on our standard format and terms and conditions.
  2. We provide you with our standard contract template, which provides a quick and simple route to setting up the contract, including credit and billing arrangements.
  3. Once both parties are happy with the details of the contract, a formal contract is sent to you.
  4. We sign and exchange contracts for our records.

You can ask us to provide a detailed design and quotation for the bulk connection.

Once you’ve accepted a quotation and notified us of the target connection date and your principal designer’s and contractor’s details, we’ll arrange for any site works which we need to deliver or support to get your bulk connection in place.

For some connections, you can choose for the work to be done by a third party, instead of us.

  1. You complete and submit section G of the water bulk supply form and/or section F of the wastewater bulk discharge form. This includes information about key contacts, date(s) of connection, and who is carrying out the work for making the physical connection to our network.
  2. We determine the extent of works required, and respond with a detailed design and quotation.
  3. You arrange for payment against the quotation, using the appropriate payment reference. You then resubmit the relevant form, ticking the box to indicate that you’ve accepted the quotation and wish for the connection work to commence.
  4. We’ll arrange a site meeting so that we’re coordinated in our understanding and approach to the works.
  5. Once everyone’s ready to go, we’ll deliver any works to get the site ready for connection.
  6. We’ll let you know when our work is complete and you can perform the necessary final steps to connect with the on-site network.
  7. You connect your supply and let us know that the site has been connected (using the usual communication channels) and we’ll update our records to reflect this.

We’ll need to set your site up on our internal systems in order for us to properly manage your meter reading, billing and general account management. Our records will have started since your first enquiry, so it’s important to update them at this stage to show that the account is ‘live’ and to allow us to respond to any future enquiries or requests in the most efficient and effective way.

If you’ve not done so already, please submit section H of the water bulk supply form and/or section G of the wastewater bulk discharge form to provide us with the information we need to manage your contract and account.