The following information has been provided by wessex water for Building over or near a public sewer/private sewer.
Guidance notes – Wessex water
Building over or near to a public sewer
Please note that where reference is made to ‘public sewer’ or ‘Section 105A sewer’ (pipe serving two or more separate units) this should also be taken to include any ‘public lateral drain’ (pipe outside the property curtilage only serving one unit).
- Wessex Water has more than 30,000 kilometres of public sewers which have sometimes been laid within the boundaries of properties.You must obtain our agreement to carry out any building work over or within three metres of a public sewer to ensure no damage is caused to it or restrictions made to the way we use and maintain the sewer. Not having a formal approval from your local water company may jeopardise the future sale of your property.
- Our preferred option is that if you find your proposals could affect a public sewer you should first consider:• avoiding the sewer. Modifications are made to your plans so that the buildings are at least three metres away from the sewer.This is often the easiest and cheapest option• diverting the sewer. If your plans cannot be modified we will usually require the sewer to be diverted. Plese refer to our diversion application form for further details which can be found on our website: www.wessexwater.co.uk/developerservices.
- On 1st October 2011, in accordance with the Water Industry (Schemes for Adoption of Private Sewers) Regulations 2011, Wessex Water became responsible for the ownership and maintenance of thousands of kilometres of formerly private sewers and lateral drains (section 105a sewers). Many of these additional pipe lines run at the rear or side of domestic properties in addition to the existing public sewers shown on our record plans.They will commonly be affected by extension proposals and either not shown on the public sewer record plans or their indicated position will be approximate only. It is important to undertake a full survey of the site and surrounding land to determine the local drainage arrangements and to contact us at an early stage if you suspect that a section 105a sewer may be affected.
- Local authorities are required to consult us where building over or near to a sewer might occur.We need to know about any building work near or over a public sewer to:• prevent the sewer collapsing. The extra weight of a new building above a sewer could cause the sewer to collapse, resulting in structural damage to the new building, interrupted drainage from other properties and sewage flooding. It will need to be repaired quickly, even if this involves taking down the building
• ensure we have access to carry out maintenance and repairs.We need to have access to the sewer and its manholes in order for us to inspect the sewer, clear blockages or carry out repairs.
- You can contact us to discuss your proposals through our sewer protection team.We will always try to be flexible and helpful in deciding with you the best way of dealing with an affected sewer.
- Wessex Water makes a charge for every application. The level of the charge will depend on the size of the sewer to be surveyed and whether a detailed investigation is necessary.
In some cases, where important sewers are involved, a formal legal agreement may also be required should it be found acceptable to allow a build over/near.
- Please be aware that every proposal is considered on its merits, and there will be occasions where an application is refused.
- We will normally be able to give you a decision within 10 working days of receipt of a complete application and we will also keep the building regulations department of the local authority informed.Under no circumstances will building over be permitted where:
- the sewer is a pressurised pumping main
- a manhole would be inside a building
- strategic sewers are affected or those which may requirefuture upgrading.
- new dwellings/buildings would be constructed over a sewer.Normally, no building over be permitted where:
- the sewer has a formal easement preventing overbuilding –this is normally shown in the deeds of a modern property
- the sewer diameter is greater than 300mm
- the sewer depth is in excess of three metresIn these cases you must contact Wessex Water for technical advice.
Please retain notes
If, having considered the alternatives, your only option is to apply for building over or near to a sewer, you should make an application to us on the attached form. In some circumstances, we will allow you to build over but you must have our written agreement to do this before you start.The sewer must be in satisfactory condition. It is recommended that an application is made before seeking planning or building regulations approval and well in advance of works commencing on the site.
If building over a sewer, you will need to arrange for a survey, usually by closed circuit television (CCTV), to be carried out before you begin work.This will assess if any repair work is needed.Any repair work required will be at your expense but the application fee will be waived.A copy of the CCTV report should be enclosed with the application form. If Wessex Water is not satisfied with the quality of the CCTV survey you will be requested to provide a suitable alternative.The CCTV report should include:
- a block plan showing the point of entry into the public sewer and length of sewer surveyed
- the distance surveyed as a running total on the video/CD/DVD of the sewer
- sewer details: type (foul/surface water), pipe size, material and pipe depthIn some instances we may also require a CCTV survey to be carried out on completion of the works.Please note that a CCTV survey will not normally be required if you are not building over a public sewer although in certain cases it will be necessary.In some circumstances, we have the right to stop your works, and have the buildings that are built over public sewers taken down.
Building over or near minor sewers up to and including 150mm (6”) diameter
Wessex Water will consider building over or near minor sewers where diversion is not practical and the extension cannot be redesigned.This includes section 105a sewers, however these may not be shown on our record plans.
Any permission will be subject to the following conditions:
- the public sewers are accurately located on site and plotted on to the deposited plans submitted for building regulations permission. For building notices the same conditions will apply
- for a sewer up to 1.5m deep the nearest edge of foundations should normally be no closer than one metre from the edge of the sewer
- for a sewer 1.5m to three metres deep, the distance between the sewer and foundations should be equal to the depth of the sewer where possible
- where foundations to the building are at any point within one metre of the sewer, they are to be carried down and formed at 150mm below the invert level of the sewer.At greater clearance an angle of 45o can be taken from a point one metre clear of the sewer up to the required footing level.
- If building over a sewer, the sewer line should be surveyed by closed circuit television and a record made of its structural condition before any work is carried out to protect both the householder and Wessex Water’s interests.This should be arranged by the applicant who will need to supply the recording and report with the formal application. On request by the householder, Wessex Water can arrange this work on a rechargeable basis, although this will take longer and costs may be higher.
- Any defects on the sewer must be made good at the householder’s expense.This may require complete replacement or repair. Guidance should be requested from Wessex Water to ensure the system is satisfactory before any further work is carried out.
- Where necessary, the sewer crossing the site must be relaid beneath the building from a new manhole (if provided) to the boundary of the site. It should be laid using approved new pipes (normally clay) with normal flexible joints and a granular bed and surround of not less than 150mm in thickness or 10mm to 14mm nominal single size or 14mm to 5mm graded granular material. Where new pipes are connected to the existing sewer either an appropriate sleeve joint or a band seal repair connector is to be used.
• Where the sewer crosses beneath any load bearing walls, the foundations of the walls are to be stopped short of the sewer by not less than 150mm, and the sewer line is to be bridged by load bearing lintels (Building Control approved) placed above it so that no loads from the structure are transmitted to the sewer pipes.The void around the sewer is to be filled with highly compressible material.
• Cantilever type slab foundations will be considered – details to be supplied for agreement.
• Where an existing chamber will come within the new building, a new manhole should be constructed to the current standard of Sewers for Adoption published by the Water Research Centre Plc on the line of the sewer outside the limits of the building, to provide a replacement point of access to the sewer. Connections to the existing chamber will need to be diverted and relaid to the new chamber.The existing chamber should be removed.All work should be carried out by a qualified contractor (see attached terms and conditions).
• All work must be inspected and approved by the building control surveyor and/or Wessex Water prior to back filling.
• It must be acknowledged that the sewerage undertaker’s easement within the site to carry out repair and maintenance to the sewer, is not in any way prejudiced by the approval of Wessex Water to the proposed building work.
Sewers over 150mm (6”) up to and including 300mm (12”) diameter
• Wessex Water will consider building over or in close the applicant must show that he has considered diverting proximity to these sewers provided that there are less the sewer, or repositioning or redesigning his proposed than approximately 25 properties served by the sewer development. Only where no other option is viable and
- conditions as for minor sewers apply
- where more than approximately 25 properties are served, using appropriate protection measures will overbuild then be considered.
Building close to or over minor public sewers
TERMS AND CONDITIONS
- The works are to be undertaken under the provisions of section 185 (and section 106 if they incorporate any new connection) of the Water Industry Act 1991.
- All works are to be carried out wholly within land owned by the applicant.
- The closure and removal of any part of the public sewer network that shall become totally redundant during the course of the works must only have served premises and land owned by the applicant. Any redundant sewer must be sealed, removed, or fully filled with grout.
- All works will be carried out at the applicants’ expense.
- The works shall be carried out in accordance with the appropriate specifications contained in the current WRc publication Sewers for Adoption – a design & construction guide for developers. A copy can be purchased from WRC plc by calling 01793 865 012 / 865 069 or online at www.webookshop.com
6. Variations to the works shall only be carried out with the prior written permission of Wessex Water.
- All work must be carried out in a workmanlike safety conscious manner and completed as soon as practicable after they have commenced. During the construction of the works adequate provision will be taken to ensure that the flow of sewage through the public sewerage system is not adversely impeded by the works.
- Sufficient notice and opportunity to monitor the works will be given to Wessex Water.
- Wessex Water reserves the right to take control of the works and/or satisfactorily complete the works with or without notice at the applicants’ cost on a fully rechargeable basis. Sufficient access to the works will be provided at all times to carry out inspections and complete the works if necessary.
- The construction of any building or extension shall be carried out with the due exercise of care to protect the public sewer network from damage at all times. Foundations and walls shall be designed and constructed in such a way so as not to place any loading on to the public sewer network.
- All drainage work must be carried out by a suitably qualified contractor. Unless agreed otherwise, the contractor should be from the list which can be found on our website www.wessexwater.co.uk/developerserices under Connecting to a public sewer.Alternatively, details can be e-mailed/posted. If you select a contractor not on the list, they should hold the appropriate City and Guilds confined spaces qualification. In addition, medical certification, method statements and risk assessments may be required.
Application to build over or near to a public sewer
Frequently asked questions
I have planning permission and have applied for building regulations approval so why do I need the approval of Wessex Water as well?
Wessex Water is responsible for maintenance and repair of public sewers and therefore development proposals close to or over our apparatus will require our formal approval to protect our interests. By law, building control must advise us of any works within 3 metres of a public sewer.
What do you consider to be close to a public sewer?
Within 3 metres of the outer edge of sewers up to 300mm diameter increasing to 6 metres for larger diameter sewers.
How do I know where the sewer is and what size it is?
The exact details of the sewer should be established by site survey carried out by the applicant or the developer / architect.
I have found a sewer pipe – how do I know if it is a private drain or public sewer?
- If the pipe only serves your property it is a private drain and you do not require our approval to build over or near to it. Building Control will monitor any works related to the protection of the drain.
- If the pipe is shared by two or more properties, or it is a drain (described above) which has left your property boundary, it is a public sewer and any work within
3 metres of its outer edge will require our approval.When is building over a public sewer not permitted?• Where over pumping mains • Where over strategic sewers • On new development sites
• Where over manholesWhat are strategic sewers?Generally sewers 225mm diameter and over as these take significant flows (although it can include sewers of smaller diameter in certain circumstances).
Why do I have to pay?
Wessex Water must recover its costs, to be fair to our existing customers, in dealing with something that a particular customer is proposing.The fee covers our costs in administering the application, evaluating the proposed works, liaison with building control officers, issuing approval and site inspection if necessary.
Why do I have to pay more for a larger sewer?
The review we need to make regarding a larger sewer is more extensive.We may need to seek operational guidance, carry out additional site visits and look at drainage area studies.The technical and administration costs would therefore be higher.
Do conservatories require the approval of Wessex Water?
Yes if you are building over or near a public sewer.
Does the sewer have a right to be in my property even if there is nothing in the property deeds?
If laid by Wessex or previous authorities, compensation will have been paid to the original landowner at the time of laying.Where laid by the property developer,Wessex (or previous authority) will have taken on the sewer with its right of location and access as part of the vesting arrangement.All public sewers are covered by statutory easement.This is normally from the outer edge of the sewer and is a minimum 6m wide although greater if sewer of large diameter. Modern properties (post 1990) will normally have specific easement details in their deeds.
What rights does Wessex Water have to prevent me from carrying out my proposed building works?
For every public sewer we have a statutory easement. In some cases this easement is supplemented by a written deed of grant, but these are rare.The statutory easement is the right in favour of Wessex to maintain, repair, replace, renew etc. its public sewers under sec 159 of the Water Industry Act 1991. If anyone does anything that interferes with our statutory easement we could seek an injunction for the removal of offending buildings and damages.
What special protection work is required?
- Foundation design in accordance with the details given in our guidance notes
- For sewers over 3m deep it is likely that pile foundations will be required or for deep footings constructed in short sections
- In certain circumstances (non – preferred) we will consider reinforced and thickened concrete slab (raft foundation), which should be designed to minimise ground disturbance as well as transfer and spread loads
- Load bearing lintels to be used where the sewer line is built over in accordance with guidance detailsWhat if an existing manhole is located within the footprint of the proposed development?Inspection chambers should be removed where they fall within a new building and if still required, replaced outside the limits of the building to standards of SFA. Internal manholes have been non – preferred for many years under building regulations and our own guidance. Internal manholes can cause a problem if access is needed and the householder is not at home.You should, therefore, look to revise your proposals to avoid the manhole or apply to divert the sewer.
Why do I have to have a CCTV survey?
This is the quickest and most efficient way of making a structural assessment of the current condition of a pipeline.
Why do I have to pay for the CCTV survey?
Because you as the customer is requesting to build over or near to our asset. Prior to agreeing to your proposals we have to be satisfied that our asset is in good condition, which Wessex are quite happy with and have no plans or requirements to expend any time or costs on.
Getting in touch with us
What if the sewer is already shown to have defects on the CCTV survey?
You will need to resolve and fund these works although we will refund the application fee.
Why do I have to pay to repair your sewer?
Because we have no immediate plans to expend any time or costs on this particular asset which is currently operating satisfactorily and to which we have un- restricted access.
Will a record of my buildover/buildnear agreement be kept by Wessex Water for reference in the future?
Yes, a record will be kept on our mapping system showing the reference number and date of agreement against a specific property (for all agreements made from 1 April 2003). This information will be used in Solicitors searches should you decide to sell your property.
For enquiries regarding this application or any other questions relating to your building or development work please contact us on: 01225 526333 (8.30am to 4.30pm, Mon – Thurs, 8.30am to 4pm, Fri).
You can wrtite to us at you can email us at
or visit our website at
Wessex Water, Developer Services, Claverton Down, Bath BA2 7WW email@example.com www.wessexwater.co.uk/developerservices
Wessex Water general contact information
(Telephone calls may be recorded to monitor quality standards.)
Billing and customer services
0845 600 3 600 (8am to 6pm, Mon – Fri)
BWBSL, 1 Clevedon Walk, Nailsea, Bristol BS48 1WA.
Please include your customer reference number and/or billing address when calling or emailing. We may contact you by telephone in response to your email to discuss your query. Please provide your phone number when you contact us.
Operations centre, Bath (main office) 01225 526 000 (8.30am to 5pm, Mon – Fri)
Wessex Water, Claverton Down Bath BA2 7WW
Emergencies and operational problems
0845 600 4 600 (8am to 6pm, Mon – Fri, emergency service at other times)
Minicom (for those with impaired hearing)
0845 730 0619
Sewage floodline (in a property)
0845 850 5959
0800 692 0692 (24 hours)