Commercial Leak Detection Services: A Business Guide

Reviewed by the DCI Leak Detection team · Last updated June 2026

A leak in a commercial building rarely announces itself. It shows up as a water bill that has crept up for no clear reason, a damp patch in a stockroom, or a tenant complaint about pressure. By the time it is obvious, water has often been escaping for weeks. For a facilities manager or landlord, that is lost money, a disruption risk and a possible insurance headache all at once. This guide explains why commercial leaks matter, how to spot one early, how detection works on a larger building, and where insurance fits in.

Why hidden leaks matter for a business

Water loss is a national problem before it ever reaches your premises. House of Commons Library research found that around 3 billion litres a day are lost to leaks across England and Wales, the equivalent of roughly 1,200 Olympic swimming pools, according to figures published by the Liberal Democrats and broadly in line with Ofwat's leakage data of around 2,869 megalitres a day in 2024-25. On your own site, a hidden leak hits the business in four ways at once.

• Cost. A leak on a metered supply runs up the bill every hour it goes unfound, and you pay for water you never used.
• Damage. Escaping water rots floors, undermines screed and drywall, and can reach stock, equipment and electrics.
• Downtime. A burst or a flooded area can close part of a building, stop trading, or force a tenant out while repairs happen.
• Liability. Where a leak affects a neighbouring unit or a tenant's goods, the question of who pays can land on the landlord or the occupier.

None of these get cheaper with time. A pinhole leak found this month is a small repair; the same leak found after it has soaked through a suspended floor is a much bigger one.

Signs of a leak in commercial premises

Commercial buildings hide leaks well. Plant rooms, voids, long pipe runs and solid floors all mask the source. These are the signals worth acting on.

• A rising water bill with no change in occupancy or use. This is often the first clue on a metered supply.
• A meter that keeps moving when everything is switched off. Take a reading last thing at night and again first thing, with no water used in between.
• A drop in water pressure across taps, washrooms or processes.
• Warm patches on the floor, which can point to a leak on a hot supply or a heating circuit.
• Damp, staining or a musty smell in stockrooms, basements or near walls, with no obvious spill.
• Unexplained mould or peeling finishes on walls and ceilings.

If your only clue is the bill, the same pattern affects homes and businesses alike. Our guide on a high water bill with no visible leak walks through the early checks before you call anyone out.

Who is responsible for the leak

This is the question that decides who pays, and it catches a lot of businesses out. The boundary of your property is the dividing line. The water company maintains the mains and the communication pipe up to your boundary. From the boundary into the building, the supply pipe is the property owner or occupier's responsibility, with the split between landlord and tenant set by the lease. Ofwat sets out this responsibility for non-household customers, and the same principle runs through every water company's guidance.

So if a leak sits on your side of the boundary, it is almost always yours to find and fix. That is why pinpointing it early, with as little excavation as possible, keeps the cost down. If the leak is on the water company's side, report it to them, but you will still want it confirmed rather than assumed.

How detection works at scale

Finding a leak in a large or busy building is about locating the exact source before anything gets opened up. The same non-invasive methods used in homes apply to commercial sites, scaled to the building. A specialist will typically work through several of these together.

• Thermal imaging. A thermal camera reveals temperature differences where water tracks under floors or behind walls, especially on hot supplies and heating circuits.
• Acoustic detection. Ground microphones and correlators listen for the distinct sound a pressurised leak makes, which helps trace buried and concealed pipes.
• Tracer gas. A safe gas mix is introduced into the pipe and rises to the surface at the leak, pinpointing it through solid floors and long runs.
• Moisture mapping. Digital moisture meters confirm how far water has spread, which sets the boundary of any access work.

On a multi-unit building or a site with long pipe runs, the survey is methodical: isolate sections, narrow the area, then confirm the exact point. The payoff is a single targeted repair instead of a guess that opens three floors. For the underlying technology and how it applies across business types, the commercial leak detection service page sets out what a survey involves. The same approach underpins general water leak detection on any premises.

The insurance angle

Water damage is one of the biggest categories of property insurance claims. The Association of British Insurers reports that insurers pay out around £1.8 million a day for escape-of-water damage, and escape of water accounts for more than a quarter of property claims. Those headline figures cover the whole market, but the lesson for a commercial property is the same: a leak found and fixed early is far cheaper than the damage it causes if left.

Many commercial property policies include trace and access cover, which pays to find the leak and to put right the damage caused by reaching it, such as lifting a floor or opening a wall. What it covers and the limit vary by policy, so check your schedule. The detail that makes a claim run smoothly is an insurer-ready report: a clear record of how the leak was found, the methods used and the access required, with photographs. To understand exactly what this cover does and does not pay for, see our guide to what trace and access cover is.

What to do if you suspect a leak

1. Confirm the loss. Take meter readings overnight with no water used to see whether the meter still moves.
2. Limit the damage. If a leak is active and you can do so safely, isolate the affected section at the stopcock or local valve.
3. Check responsibility. Establish whether the leak is on your side of the boundary or the water company's.
4. Check your cover. Confirm whether your policy includes trace and access, and note the limit and excess.
5. Get a professional survey. A specialist pinpoints the source with non-invasive equipment and documents everything for your records and any claim.
6. Repair and reinstate. With the exact location known, the repair stays small and the building keeps running.

Commercial leak detection in Cornwall & Devon

Across Cornwall and Devon we survey shops, offices, units, schools, care settings and rental properties, finding hidden leaks with the least possible disruption to trading. Most surveys happen with the business open, and where access work is needed it is targeted to the exact spot. You get the leak located fast, with the documentation an insurer needs and a clear picture of what the repair involves. If you manage a portfolio or a single site and the numbers are not adding up, that is usually the moment to have it checked.

Frequently asked questions