During October 2011 the majority of previously private sewers and drains were transferred into public ownership to be repaired and maintained by local water authorities. This had the benefit of releasing hundreds of thousands of home owners from the responsibility for maintaining sewers that ran through the boundaries of their properties.

It does however mean that many more home owners have since needed the prior approval of their local water authority in the form of a Build Over Agreement when building work involving new foundations, underpinning, piling or basements is to take place within 3 metres of or over the route of an existing public sewer or drain.

What is a Build Over Agreement?

A Build Over Agreement is a document in which the home owner gives the local water authority assurances that the work to be carried out will not have a detrimental effect on the publicly owned sewer beneath or nearby. It also sets out the local water authority’s access rights to the sewer so it can continue to be repaired and maintained by them. If you are planning on building close to or over an adopted sewer you should contact the local water authority before beginning any work to find out what their requirements are.

How do I know if there are Adopted Sewers with my Boundaries?

When buying a property, you will be offered a Drainage & Water Search, which will include a plan showing the location of adopted sewers in relation to the property. If any adopted sewers are identified as within the boundaries of the property, your conveyancer should raise suitable enquiries with the seller’s solicitor in respect of it having been built over. They should also provide you with a copy of the report including the plan showing the location of the adopted sewers.

What is the benefit of a Build Over Agreement?

Conservatories and extensions are the usual offenders when properties are built over an adopted sewer. If the building work was carried out after the adoption of the sewer and a Build Over Agreement was not obtained before the work was commenced, the local water authority has a statutory right to enter onto the property to access the sewer, even if it means damaging or demolishing the structure situated over the sewer. Whilst most local water authorities will try to avoid causing damage, there is no obligation on them to return the property to its previous condition. If a Build Over Agreement was entered into then the Water Company do not have the right to remove or demolish the structure over the sewer, and they must repair any damage caused in accessing and repairing the adopted sewer.

What if a Property doesn’t have a Build Over Agreement?

The quickest, cheapest and most common option to deal with risk arising from a property being built over an adopted sewer is for the seller to give the buyer an indemnity insurance policy, which protects future property owners against financial loss incurred in the event of the local water authority causing damage to the property when accessing and repairing an adopted sewer beneath it. This option is not always available as it must be approved by the buyer’s lender first. Additionally, if any party to the transaction has revealed the existence of the building built over the adopted sewer to the local water authority, insurance will not be available.

Another option is for the buyer to insist that the seller instruct a CCTV survey of the sewer and forward the footage to the local water authority, requesting they:

i) approve the condition of the sewer; and
ii) provide a comfort letter confirming the sewer is in satisfactory condition and that they will not take steps to demolish the building situated over the adopted sewer.

This will also need to be sent to the buyer’s mortgage lender for them to approve.

The best option though, is for the buyer to insist that before exchange of contracts the seller enters into a retrospective Build Over Agreement with the local water authority. Whilst this is usually the most expensive and time-consuming option available, it provides both the buyer and their lender with the most comprehensive and binding protection in relation to this issue. This risk is that for some reason the local water authority refuses to enter into a retrospective agreement without additional works being carried out, which the seller may not be able to afford.

If you are considering selling your property and are aware that some or all of it is built over an adopted sewer, it is worth discussing your options with your conveyancer before putting the property up for sale.

To speak to a member of Farleys’ conveyancing team please call 0845 287 0939 or submit your enquiry online.