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Close Proximity to Assets (Water & Sewers)

Building Near a Public Watermain

Building near a Public Watermain

Guidance notes

NI Water has a legal requirement to maintain a wholesome supply of water to its customers.

To ensure service delivery NI Water needs to be able to maintain, repair, refurbish and replace water mains as and when the need arises. This requires access to our infrastructure at all times, and is supported with legislation under Article 236 of the Water and Sewerage Services (Northern Ireland) Order 2006.

The following guidance sets out NI Water’s requirements to deliver its statutory duties, mitigate potential damage to property and minimise Health and Safety Risks should the infrastructure fail.

Access/Protection Zones

The minimum clearance distances detailed below are primarily determined based on operational requirements, and the strategic importance of the asset within the Network; however, other factors such as site-specific topography, high-pressure systems and depth of the main may determine greater clearance distances.

Pipe DiameterMinimum Access Distance either side of pipe
Up to 180mm3 metres
181 - 350mm4 metres
351 – 600mm6 metres
Greater than 600mmRequires consultation and approval from NI Water

Note: Table assumes pipe at nominal cover to crown of <1.5m

NI Water acknowledges that there may be locations across the Province where buildings have previously been sited within the access/protection zone. This is no longer acceptable unless approved by NI Water following full consultation prior to planning approval (see Exceptional Approval below).

Design of New Developments

Where a development is planned in the vicinity of existing water mains, the onus is on the developer to carry out exploratory excavations. This must determine the exact line and level of the pipework prior to finalising the proposed layout for the site. The layout should be designed to ensure that NI Water infrastructure is located within a verge, road or public green space within the site; the design should not result in the land, under which existing mains are located, becoming private property.

Building over a water main is not allowed under any circumstances

Any proposed increase in ground levels in the access/protection zone needs to be agreed with NI Water to avoid overloading and settlement of the pipework or hampering of operational repairs.

Exception Approval

NI Water recognise that in some circumstances that site-specific conditions cannot afford the provision of the distances specified above. In these cases it may be possible for NI Water to grant ‘exception approval’ provided an engineering solution is put in place to protect both the pipework and the proposed building(s). It must also still permit access for any future maintenance or replacement work required under our statutory duties. The developer should therefore consult with NI Water as soon as possible and prior to seeking planning approval for the site.

Provided reasonable access to NI Water assets are maintained, engineering solutions can include:

  • the construction of foundations at a level below NI Water infrastructure to protect the integrity of the building
  • provision of a protective structure to avoid undermining of buildings should the main fail
  • any other proposal that would mitigate the risk to both NI Water assets and the proposed development

Diversion Option

If Access/Protection Zones cannot be achieved diversion of NI Water infrastructure may be an option provided it is considered practical and the developer is prepared to meet all costs involved.

This will be subject to a separate formal agreement with NI Water covered under Article 247 of the Water and Sewerage Services (Northern Ireland) Order 2006.

Customers wishing to apply to divert a public water main should submit a completed WD-A247 Form

Construction Phase

The developer should determine line and level of the existing watermains and put in place mitigating measures as required to avoid damage during construction. If cover to the watermain is less than 750mm the developer should contact NI Water. In some cases, there may be a need to design and construct an engineering solution to protect the pipework from any future loading. 

If any excavation work is required within the access/protection zone and close to the water main, the developer should submit a Method Statement and Risk Assessment to NI Water’s Water Performance Team at WPL[DOT]assetperformance[AT]niwater[DOT]com, 21 days in advance of the works. This will allow time for liaison with local Operational Staff and the preparation of contingency measures. 

Access to the protection zone shall be kept clear and unrestricted at all times i.e. construction materials and excavated material should not be stored there.

Notification to Future Property Owners

NI Water requires developers to notify future property owners of the land-use restriction near water mains. These must be included in the restrictions within the Deed of Conditions such that they remain visible to all future property owners and are in the public domain.


NI Water has a statutory duty to ensure its operations do not pose a risk to others. It is NI Water policy to legally contest any infringements of above.

Further Information

If you have any queries please contact Developer Services at:

Developer Services - Servicing Team Northern Ireland Water

Ballykeel Office

188 Larne Road



Co Antrim BT42 3HA

Telephone: 03458 770 003
Email:  developerservices[AT]niwater[DOT]com

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