Build Over Agreement: Explained 

Thames Water are responsible for maintaining public sewers and drains around London. They need to make sure that the works you are undertaking doesn’t restrict their ability to access their pipes in the future.

Do I need to submit an application?

If you are building within three meters of a public sewer (a pipe serving more than one property), then you will need to submit an application to Thames Water. So how do you know if you have public pipes within 3m of your property? You don’t have x-ray vision; how could you possibly know what lies beneath your garden furniture and flowerbeds? Well, there are a few options open to you to find out. If you have a lot of time on your hands, you can visit your local council and inspect their sewer maps. Alternatively, you can pay for a ‘asset location search’ from the Thames Water Property Searches team, to determine whether your works are within 3m of a public sewer. This fee can vary a little but for a typical Victorian terrace it’s around the £60 mark. Another option is wait until your builder has started the works on-site. Once the pipes are exposed, most contractors will be able to tell you if you have a public or private sewer. It is worth noting that there is a part of the application which asks whether your commenced works on-site. You aren’t penalised for starting before the application is submitted, but you run a small risk that Thames Water requests amendments to your plans.  

How do I submit?

Once you are ready to submit, there are two types of applications. The first is an application for a self-certified build over agreement, but Thames Water will only grant this is you are able to confirm that your plans pose little risk to the pipes. It’s worth giving it try as it’s free. If you don’t meet the requirements for the self-certified agreement, you’ll need to apply for an approved build over agreement, which includes a fee payable to Thames Water. For this application you’ll need to know the diameter of your drains. The property search you’ve undertaken (mentioned above) will tell you this, or again, your builder can always tell you if you’ve commenced on-site and exposed the drains. You’ll also need a site location plan, a cross-sectional foundation plan and existing and proposed floorplans. You submit this application online for approx. £299 or you can do it via post for £343. 

How can Home Tales help?

If you would like help with your Thames Water application, we have a service that takes care of everything for you. We fill in the application and gather the relevant details for you, then submit to Thames Water on your behalf. Thames Water review the documentation and once they are happy with the proposal, they will issue a build over agreement. 

It’s worth pointing out that if you don’t follow the appropriate procedure with Thames Water, your Building Control Officer will not sign off on your build and issue your Building Regulations completion certificate. Thames Water do hold legal powers (under Sections 159 & 171 of the Water Industry Act 1991) and they can seek an injunction to remove the building and recover damages if you don’t seek their approval prior to undertaking the work. You will also need Building Control sign off if you want to sell your home in the future, so it’s a pretty good one to take seriously.  

If anything is unclear, or if you have any questions, please don’t hesitate to contact our team on 0207 043 2378 or email us at hello@hometales.co.uk.