Portsmouth Water to use Openreach fibre to listen for leaks

Portsmouth Water will introduce Lightsonic's Distributed Acoustic Sensing (DAS) technology across parts of its network (Water Magazine). The system turns existing Openreach fibre-optic cables that run near water pipes into a continuous listening network. Portsmouth follows Affinity Water and Southern Water in using the service.

What we know

• Detection: the system reads changes in light signals along the fibre caused by vibrations from a leak. Lightsonic says it can locate potential leaks to within 10 metres.
• Infrastructure: it uses Openreach's Full Fibre network rather than new sensors in the ground.
• Track record: Lightsonic says technicians using the Openreach partnership have found up to four times more leaks than with traditional methods. It says the system saves more than one million litres a day for every 100km of network.
• Timing: rollout begins in December 2026, ahead of winter, when cold weather increases bursts.

Chief executive Bob Taylor said the technology would help the company "find more leaks across our network and carry out repairs sooner".

What others are reporting

ISPreview reported the deal on 23 October and adds the limits. The method works only where a leak is close to Openreach cables, and it currently runs on spare fibres rather than live broadband lines. Openreach plans to extend it to active fibre but has not yet done so. The outlet also notes that the service currently depends on Openreach, though alternative fibre networks could offer it in future. Openreach's Trevor Linney said there was "growing interest from water companies".

Background

The technology was first trialled with Affinity Water at five sites around London, covering 650km of pipes. In its first three months it located more than 100 leaks and was estimated to save about 2 million litres a day (The Register). The Register's caveat was blunt: detection saves water only if companies fix what it finds, and it described the wider sector's response as "positive noises" at the time.

Southern Water followed in September, planning to trial the system over the winter. ISPreview reported that Affinity's savings had risen above 4 million litres a day across the 650km (ISPreview). The same report notes that about 60% of England's water mains are 45 years old and 13% are more than 100 years old.

3,336km

Source: Environment Agency ↗

Portsmouth is a small company with a 3,336km network (Environment Agency). That makes its rollout a useful test of how much of a network can be covered from existing fibre.

What we don't know yet

• How many kilometres of Portsmouth's network will be covered, and what it will cost.
• Whether results will be published independently of Lightsonic's own figures.
• When live, rather than spare, fibres will be usable.

What to watch

• First results from Portsmouth and Southern Water over the winter.
• Whether Affinity moves from pilot to full contract.
• Ofwat's leakage reporting for 2026-27, to see whether detection gains turn into lower reported leakage.