Last edited 21 Jul 2021

Private sewer


A pipe carrying sewage (waste water and excrement) that serves only one property is referred to as a drain. Drains are privately owned and maintained as far as the boundary of the property. Beyond the boundary of the property a drain is referred to as a public lateral drain.

A pipe that serves more than one property is referred to as a sewer. Sewers that connect to the public sewer network are referred to as public sewers.

Under the Public Health Act 1936 all sewers (as defined by the Public Health Act 1875) which were in existence on 1 October 1937 became public sewers. After 1937 new sewers were only public if they were laid or adopted by the sewerage undertaker.

However, on 1 October 2011 in England and Wales, private sewers and lateral drains that were connected to the public sewer before 1 July 2011 were transferred to the ownership of the regulated sewerage companies (generally water companies).

This means that property owners only remain responsible for drains that serve only their own property, up to the point they connect to another drain or sewer, or as far as the boundary of their property. In the case of blocks of flats, the property owner(s) are responsible for the drain as far as the boundary of the property.

Properties not connected to the public sewer network, for example if they have a septic tank or cesspit, are not affected by this change, and their sewers or drains remain private. In addition, large commercial sites with multiple occupants may have private sewers or drains, as may sites in which sewers or drains discharge to a watercourse. Sewers owned by Railway Authorities also remain private.

New or existing sewers or lateral drains can be adopted by a sewerage company under Section 102 of the Water Industry Act 1991 (existing sewers) or section 104 of the Water Industry Act 1991 (new sewers). The sewerage company will then maintain them at their own expense.

Successful ‘adoption’ of sewers requires that they are constructed to required standards. If they are not, it may then be necessary to carry out remedial works to bring them up to an adoptable standard.

For more information see:

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