A conservatory has been built within 3 metres of a public sewer without the consent of the water undertaker

What are the possible sanctions for doing this?

United Kingdom Publication September 2020

First published by LexisNexis

When the conservatory was constructed is an important consideration. Private sewers and lateral drains that were connected to the public sewer before 1 July 2011 were transferred on 1 October 2011 to sewerage undertakers. It is common to find conservatories and other extensions constructed less than 3 metres from a public sewer that was not a public sewer at the time the conservatory/extension was constructed, but was instead a private sewer the responsibility of the homeowner.

If the conservatory was constructed prior to 1 July 2011, then it will have required express planning permission or permitted development rights, and it may have required building regulations approval.

It would not have required a build over agreement from the sewerage undertaker if the sewer was private.

Building Regulations 2010, SI 2010/2214, Sch 1

Under Part H4 of Schedule 1 to the Building Regulations 2010, SI 2010/2214, the consent of the sewerage undertaker is required for building works over a public sewer. This includes both foul and surface water sewers. Where a public sewer runs under land, the homeowner cannot build on or within three meters of the centre line of the sewer without the consent of the sewerage undertaker. This consent is the ‘build over agreement’. Consent is required before works commence and can be refused.

The reason for this restriction is to:

  • avoid damaging the sewer
  • not obstruct reasonable access to any manhole/inspection chamber
  • ensure that, in the event that the sewer needs to be replaced, there is a satisfactory diversionary route, or the building/extension will not unduly obstruct work to replace the sewer on its present alignment
  • ensure the risk of damage to the building in the event that the sewer fails is not excessive

These formerly private and now public sewers are now protected by statutory easements. The positive news for homeowners is that their sewer pipes are protected, and they have the ability to drain through third party land. However, the homeowner’s land does now contain an adopted sewer, and it is burdened by a statutory easement 3 metres either side of the centre line of the sewer.

All sewerage undertakers have statutory rights to access public sewers that lie within private land. This includes sewers that lie under or close to a property. Where build over consent has been granted, sewerage undertakers will generally attempt to access the sewer without disturbing the property. When this is unavoidable, they will repair any damage caused, within reason. This will be set out in the terms of the build over agreement. However, where a sewer has been built over without consent, sewerage undertakers have the right to access and protect the sewer by whatever means they consider appropriate. This can include requiring that any buildings affecting or blocking access to a public sewer are altered or removed, at the homeowner’s expense. In reality, however, undertakers have machinery which will usually allow them to access a damaged pipe from a different, unobstructed point and will avoid causing damage wherever possible, but a risk still remains.

This potential risk is problematic where the conservatory was constructed before 1 July 2011. There is also a breach of the statutory easement. Some sewerage undertakers suggest that they may take a relaxed stance where the works were carried out in accordance with building control consents and measures taken to protect the sewer pipes. There are two solutions to this:

  • taking out an indemnity insurance policy which may well be insisted upon by a mortgage lender prior to a house being purchased
  • obtaining a retrospective build over agreement from the sewerage undertaker

The insurance policy will cover the costs of either fixing damage to the property or rebuilding works where the sewerage undertaker exercises powers to access the sewer and causes property damage, or the costs of diverting the sewer. This option will be the quickest and cheapest option and avoids alerting the sewerage undertaker to work they may not agree to. A sewerage undertaker can refuse to grant a retrospective build over agreement. If they refuse then insurance is unlikely to be available. Even if consent is granted, the homeowner may be requested to make changes to the property which could result in significant cost being incurred. Insurance is the more common solution.

If the conservatory was constructed more recently without a build over agreement then the same sanctions and same solutions are available. It is worth noting that if the conservatory required building regulations approval, then the building inspector may require to see a build over agreement before signing off works.

Where there is a failure to obtain building regulations approval for works, the local authority are entitled to inspect, and if the works do not comply with the building regulations, serve a notice under section 36 of the Building Act 1984 (BA 1984) requiring the homeowner (who may not be the same person as commissioned the work) to put it right or, if that would not be possible, return the property to its former state. Failure to comply with a BA 1984, s 36 notice is an offence and could lead to the homeowner being prosecuted, as well as paying the local authority’s costs of correcting the breach.


Head of Planning; Partner

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