How fibre broadband is helping save millions of litres of water a day
By Abby Chicken, Openreach's Head of Sustainability
Every day, England and Wales lose around three billion litres of treated drinking water through leaks - the equivalent of more than 1,200 Olympic swimming pools disappearing beneath our feet. It’s one of the biggest environmental challenges facing the UK, and one the water industry has committed to halving by 2050.
But a new collaboration between Openreach, Affinity Water and UK technology company Lightsonic suggests part of the solution could be hiding in plain sight - inside the fibre broadband cables already running beneath our streets.
In just three months, a pioneering fibre optic sensing pilot has helped save two million litres of water every day, simply by listening for leaks. And its potential stretches far beyond water.
Turning fibre optics into a sustainability tool
The pilot uses a technology called Distributed Acoustic Sensing (DAS). It transforms Openreach’s full fibre network into a continuous sensing system, using thousands of tiny ‘virtual sensors’ to pick up the minute vibrations caused by leaks in nearby water pipes.
Because it repurposes fibre that’s already in the ground, the system offers a low-carbon, low-impact way to monitor water networks - without installing new hardware or digging up roads.
Together with Affinity Water, Lightsonic has deployed the tech across 650km of water mains in five trial areas. Early results are impressive: more than 100 leaks identified and around 700 million litres of water a year prevented from going to waste - enough to supply roughly 10,000 people.
That isn’t just a win for water security. It’s a win for the planet.
Why water savings matter
Water and carbon are tightly linked. Treating, pumping and distributing clean water is energy intensive - so every litre saved cuts emissions.
Saving two megalitres of water a day avoids an estimated 140 tonnes of CO₂ a year, simply because less water needs to be abstracted, treated and moved around the network.
Spotting leaks early also reduces emergency repairs and unplanned roadworks. That means fewer vehicle miles, less disruption for communities and lower carbon impacts from maintenance.
UK policy is also increasingly shifting toward stricter expectations on leak management, long-term resilience, and better use of existing infrastructure.
Using what’s already in the ground
One of the most sustainable aspects of this approach is its simplicity: it builds on infrastructure that already exists. Openreach’s full fibre network is widespread. It needs no new sensors, no extra plastic or power-hungry devices, no new excavation.
It’s a circular approach - creating more value and more resilience from the network we already have.
Smarter repairs, smaller footprint
DAS provides 24/7 monitoring, detecting leaks as they begin - not weeks later. Machine learning helps to filter out background and pinpoint issues to within a few metres. For water companies that means:
- Faster, more targeted repairs
- less exploratory digging
- fewer emergency callouts
- far less inconvenience for residents, commuters, and businesses.
And because the system runs over Openreach’s network, it can be scaled across the UK rapidly, without the environmental cost of installing new equipment.
A glimpse of the future
Fibre sensing doesn’t stop at water. The same approach can help detect gas leaks, structural issues in bridges and tunnels, and security disturbances along utility corridors.
By using our existing infrastructure to protect critical services, we can cut waste, reduce emissions and strengthen the UK’s national resilience.
The early results are already clear: fibre networks can be a powerful ally in the fight against climate change - saving water, cutting carbon and reducing disruption. All made possible by the broadband lines already connecting our homes.
As this capability scales, it opens the door for wider future collaboration across utilities - supporting shared resilience planning and more efficient management of critical infrastructure as climate driven risks grow.
