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Renewing our water mains

Many of our pipes are over 70 years of age and are in need of replacing. They are made from iron and are laid in heavy clay soil that eats into the metal, causing corrosion.

This corrosion weakens the structure of the pipe resulting in small holes and cracks appearing over time. As the water leaks through these holes and cracks, the pipe becomes even weaker which can lead to a burst water main.

  • Why are the mains being updated?

    Old iron pipes means...
    • Cast iron pipes that crack when moved
    • Burst mains and leaks wasting water
    • Worn out corroded water mains
    • Water being cut off for emergency work
    • Traffic disruption and holes in the road

    When a water main bursts we have to repair it as quickly as possible, as the escaping water is a potential threat to public safety and can damage property and the environment.

    We are replacing these old iron water mains with new plastic pipes so that we can provide you with a reliable supply of drinking water and reduce the disruption caused to your community, when a water main bursts.

    New pipe (cross section)

    New plastic pipes means...
    • Flexible plastic water mains
    • Water friendly pipes
    • Trouble free pipes
    • A reliable water supply 24/7
    • Planned traffic friendly working
  • Identifying pipes that need renewing

    With 16,500 kilometres of pipes supplying over 1.2 million customer properties renewing our network is a non-stop job.

    Renewing these pipes ensures a continuous, secure supply of top quality tap water at the lowest possible price to our customers. Renewing pipes is a costly operation meaning careful prioritising of those pipes that most urgently need replacing. We constantly check the condition of our pipes and use historical data to predict which are most likely to burst. When selecting a renewal scheme we also check that our work won’t cause unnecessary interruptions to customer supplies, flooding or major traffic disruption.

    Once we’ve identified the most urgent pipes for renewal, we liaise with the Highways Authorities to agree when we can carry out the work.  We appreciate that renewals can cause disruption and inconvenience to our customers, but with careful design and planning we will make sure we renew the right pipes at the right time at a reasonable cost to ensure our infrastructure is fit for 21st century needs.

Current Works

  • Harefield to Oxhey Woods Trunk Main

    Our purpose is to provide high quality water, whilst protecting the environment for all generations.

    Chalk streams are under threat from the impacts of climate change and the demand for water. Historical river alterations of these precious habits have also meant that some stretches of chalk streams have lost their natural path and connection to groundwater.

    Our trunk main projects are part of our sustainability reductions programme which will ensure we have enough water to meet demand whilst leaving more in the environment. This programme plays a vital part in improving the health of the globally rare chalk stream habitats that run through our supply area.

    We have committed to reduce the amount of water we abstract from groundwater sources by over 36 million liters across our supply area between 2020 - 2025. And ultimately to end unsustainable abstraction from chalk groundwater sources.

    By reducing abstraction from chalk groundwater sources we aim to sustain these precious resources for future generations and see flourishing habitats and biodiversity around these rivers. Alongside this our Revitalising rivers programme will help to restore sections of our chalk rivers to improve local habitats and wildlife.

    As a water supply company we need to ensure that as we make changes to benefit the environment we continue to supply high quality drinking water to our customers and maintain the security of that supply.

    The sustainability reductions programme will do this by constructing a number of new assets across our supply network by 2023/24. These range from new pumps, water mains and water treatment facilities. One of the assets that has been identified is a new trunk main between Harefield Reservoir and Oxhey Wood Reservoir.

    Once installed this pipeline will allow us to move water from one water resource zone to another ensuring a resilient customer supply and enabling the reductions from groundwater sources to happen.

    For more information, Our Business Plan for 2020 to 2025 outlines how we will take significant steps to improve the environment in the areas in which we operate and continue to provide high quality water to our customers.

    How will it affect customers?

    Road closures and diversion routes will be needed to complete the project.

    We have identified domestic and commercial customers that will be affected by the works and will be providing information to them in advance, detailing a point of contact, the expected impact and duration.

    Hillingdon Highways Department are working closely with us to ensure that road closures, diversions and traffic management plans consider key infrastructure such as hospitals, vaccination and testing centres.

    Work will mostly be between 08:00hrs – 18:00 hrs Monday to Friday with occasional weekend working agreed in advance.

    This page will be kept up to date with information on the project.

    Where will we be working?

    Work will be taking place on private land between Harefield Reservoir and Cygnet Close and in the following streets:

    Northwood - Cygnet Close

    Duck Hill - The Avenue

    Rickmansworth Road - High Street

    Northwood Way - Hillside Road

    Potter Street Hill - Sandy Lane

    COVID 19

    We are fully COVID-19 compliant and our teams follow Government & Public Health protocols to ensure the safety of customers and staff.

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