It is an offence under Article 236 of the Water and Sewerage Services (Northern Ireland) Order 2006 (as amended Water and Sewerage Services Act (Northern Ireland) 2016), to realign, build over or near watermains, public sewers, pipes and associated works owned and maintained by Northern Ireland Water unless with the prior consent by NI Water.
If you have located or have reason to believe that a public sewer is within the Protected Strip, which is noted as
- within 3m or 1.5 times the depth of the proposed structure (whichever is the greater); OR
- within 15m if piling is proposed; OR
- if your proposal involves the reduction or increase of the existing ground level within the Protected Strip, and construction of any building / structure (this includes any non-habitable structures, ie retaining walls) is proposed within the Protected Strip you MUST consider relocating your building / structure.
You must consider the realignment of the public sewer in the first instance. Please refer to the Realignment of a Public Sewer guidance notes. If however, a realignment is not feasible due to site constraints, please provide evidence of the reasoning behind this decision when making the application to Build Over / Near the Public Sewer and include it in your application pack.
If you have considered all the alternatives and the only option appears to be to build over or near the public sewer, please forward your proposals to us for assessment using application form SBO-A236.
Please note that a Building Over / Near a Public Sewer Agreement may not always be permissible.
It should be noted that Northern Ireland Water will not consider a proposal to build over a public sewer for a new building.
Please determine the exact location of the affected public sewer(s) prior to making a Build Over or Near a Public Sewer application, as failure to do so may result in a delay in the processing of your application.
Where this is not possible Northern Ireland Water may be willing to determine the location on site. However, this will be at your expense. To avail of this service please email a location plan to waterline[AT]niwater[DOT]com to request the location of the public sewer to be identified on site.
The current fees and charges associated with the Building Over or Near a Public Sewer process, in accordance with the current Scheme of Charges are:
- Application Fee - this includes appraisal of your proposals (non-returnable);
- Inspection Fee - payable at the time of submitting the Inspection Application (SBO-A236-Insp) on completion of the work.
- Request for NIW to locate the public sewer on site - if applicable.
Although we will consider every case sympathetically:
- it is possible that permission to build over public sewers which are classified as critical public sewers may not be given.
- it may not be possible to permit a build over / near a public sewer if ground levels are being altered on site.
- it may not be possible to permit a build over / near a public sewer if future maintenance access to NIW assets in the locality are diminished.
- Under no circumstances is construction allowed directly over a pumping main. Restrictions WILL also apply as to how close you can build to such public sewers.
- Manholes, were possible must be outside the structure. Where this is not possible, they must be sealed at finished floor level and accessible without excavation. Any floor coverings that will need to be removed for access purposes will be replaced at the owner’s expense.
- Inspection chambers MUST NOT be constructed on the line of the public sewer.
- Lateral connections, where possible, should connect to the public sewer outside of the structure.
Building Over Non-Critical Public sewers
It may be possible to build over non-critical public sewers, which often run along the back of older properties and are affected by extensions to the rear of the property. In most instances building over/near these public sewers will be permitted, providing that certain structural protective measures are taken. The standard protective measures are as follows:
- CCTV Survey will be required to determine the existing condition and location of the affected public sewer;
- Foundations must be taken down to a minimum of 150mm below the public sewer invert level. No structures (footings, walls etc) running parallel, or adjacent to the line of the public sewer will be allowed within 500mm of the public sewer (in plan); and
- Crossings must be supported using pre-cast (or adequately designed cast in-situ) concrete lintels/beams. (Please refer to the ‘Typical Detail for Building Over a Public sewer’ on page 5)
- Any clay or damaged public sewer under the proposed building MUST be replaced with a new sewer pipe of an equivalent size (material to be agreed with NIW). A detailed method statement will be required.
Piling Works Near Public sewers (within 15m of a public sewer)
Where piling works are being carried out care must be taken to avoid any damage to the public sewers. The position of the public sewer MUST be established by electronic survey. Should the survey suggest that the public sewer is likely to be within 15 metres of the piling works, trial holes may be required to establish the exact location of the public sewer. Piling systems must be chosen so that resultant vibration is kept to a minimum and a suitable method statement, inclusive of the measures to be taken if the public sewer is damaged, must accompany the application.
Building Over or Near a Public Sewer Agreement
Once the Wastewater Approvals Technical Adviser has assessed your proposals and agreed the associated detailed design drawings, they will issue a Building Over or Near a Public Sewer Agreement via email.
When you receive the Building Over or Near a Public Sewer Agreement
- you will be required to print it and gain all of the necessary signatures prior to scanning and emailing it to email@example.com.
- if there is any loan / mortgage on the associated property, the Loan / mortgage provider MUST sign the Building Over or Near a Public Sewer Agreement prior to it being returned to NIW.
- you must hold and provide current Home Insurance details which must include buildings cover.
- No work must commence on site until the Assessment and authorisation of the Building Over or Near a Public Sewer Agreement has be completed and the authorised Agreement returned to the applicant.