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Sewage and drainage

Drains are single pipelines which convey foul sewage and/or surface water run-off from a single property. A drain is still a drain even if it goes past the boundary of your property and remains so until it joins a sewer.

Sewers are pipelines which normally convey foul sewage and/or surface water run-off from more than one property. Sewers may be either private or public sewers.


The council has no direct responsibility for foul water drains, sewers, septic tanks, cess pits etc. Environmental Protections role is to ensure that the person or persons responsible take appropriate remedial action if a drainage problem (e.g. a sewer blockage causing leakage) presents a risk to public health. However the Council has no powers enabling it to require water undertakers to clear blockages or repair public sewers.

The Water Industry (Schemes for Adoption of Private Sewers) Regulations 2011 came into force on the 1 October 2011 when the Law and the responsibility for sewers and drains changed.

From 1 October 2011 individual householders are only responsible for the drain serving the property up to the boundary of the property. Beyond that point, the responsibility rests with the sewage undertaker.

Exceptions to this rule will include:

  • Properties not served by a public sewer: If your property is served by a cesspool, septic tank or other package treatment plant the responsibility will remain with all those properties having the use of it.
  • Properties where the sewer or drain is owned by a railway undertaker or where the sewer or drain lies within Crown Land:  In the case of Crown Land the relevant Government Department must have made a declaration that it does not want the legislation to apply to particular land.  It is anticipated that this will apply to land occupied by the Armed Forces.

If the blockage or fault only affects your drain and is within the boundary of the property it is your responsibility. Firstly it is always worth contacting your household insurance as your policy may cover you for drain clearance.  If this fails then you will need to contact a reputable plumber or drainage company, which can be identified through a phone directory or the internet. It is recommended you obtain several quotes for the work to ensure you get value for money.

If the blockage affects more than one property or is outside of your property boundary, you will need to contact the water company even if you think one of the exemptions apply. The water company will either investigate and clear the blockage or advise you if it believes the sewer or drain is not their responsibility. Most of Wiltshire is covered by Wessex or Thames Water although some other companies also provide public sewerage services in the county. If you are unsure who provides your service please check your bill.

Wessex Water  0345 600 4 600 (Emergency 24 hrs a day)
Thames Water 0800 316 9800 (Emergency 24hrs a day)


For all of these types of system responsibility usually lies with the properties using the tank, even if it is located on only one premises. If there is a problem with your system you will need to contact a private company that specialises in these matters so they can inspect and repair any defects.

Septic tanks reduce the bacterial and nutrient load (e.g. phosphates and nitrates) of the effluent discharged into it and to stop the effluent from polluting watercourses or drinking water sources in the vicinity. They comprise of compartments for deposit of waste and settlement/treatment where bacterial activity creates a sludge that accumulates over time and requires regular removal.

A cess pool or pit is essentially a leak-proof holding tank for the waste; they are usually much larger than septic tanks. A cess pool needs to be emptied once it is full; this will usually be more frequently than for a septic tank because the liquid needs to be removed as well as sludge because there is no percolation into the soil.

A small sewage treatment plant is a part-mechanical system that treats the liquid so it’s clean enough to go into a river or stream.

The Environment Agency have produced a set of rules for septic tanks and small sewage treatment plant.


In some circumstances, where there is a defective drain or sewage system, the council can serve a legal notice on the owner or occupier of the building(s) served which requires defects to be repaired. If the notice is not complied with the council may arrange for the work to be completed and recover the costs from the person responsible, they may also apply to the courts for a prosecution.

Enforcement will be carried out in accordance with Public Protection Enforcement Policy.


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Last updated: 5 March 2018 | Last reviewed: 5 March 2018