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Legionella Screen
A commercial plant room: insulated hot water storage tanks and copper distribution pipework with sampling valves

Buildings, cooling towers, spa pools

A sample answers one question, at one point, on one day

Which point, and on which day, is the entire test. We draw the sampling plan on your schematic, take the samples with the temperature and residual recorded beside them, and have them cultured in an accredited laboratory.

We test water, not people. If you are concerned that someone is unwell, contact a doctor or your local health department. Nothing on this site is medical advice.

Four questions

Request testing

We do not ask for temperatures or treatment records here, because they should be read rather than remembered. Bring them to the call.

To withdraw consent, reply STOP to any text or say so on the phone. The number is removed the same day. How the details are handled is set out in the privacy policy.

The plan before the bottles

A sampling plan is drawn on the schematic, not made from the taps nearest the door. Where the samples come from decides what the result is worth.

We sell no treatment

No chemicals, no dosing contracts, no remedial works, no commission on any of them. A company that supplies the treatment has a reason to conclude you need more of it.

We test water, not people

We report what was found and where. We do not interpret a result as a health matter, because that is a clinical judgement and we are not clinicians.

Where it hides

The dead leg nobody can see on a walk-round

A branch to a removed fixture, an oversized run to an outlet nobody uses, a capped tee left after a refurbishment. Warm, still, and connected to everything else. Invisible in the corridor and obvious on the drawing, which is why a sampling plan starts on the schematic.

How sampling points are chosen

Cutaway of a building hot water system: calorifier, recirculation loop, risers, a dead leg and a rooftop cooling tower
Sampling planWater management programCulture methodColony forming unitsDead legThermostatic mixing valveRecirculation temperatureCooling tower driftValidation samplingChain of custody

What a result is worth

One bottle answers one question, on one day

  1. A stainless steel tap on a tiled institutional wall with water running clear

    In use

    An outlet in service, running clear. Nothing here looks like a problem, which is exactly why a sampling plan is written from the layout of the system rather than from what someone noticed.

  2. The same tap with a sterile clear sample bottle held under the stream, its cap resting beside it

    Sampled

    One bottle answers one question, at one point, on one day. What that answer is worth depends entirely on where the point was, whether the outlet was flushed first, and how fast the bottle reached the laboratory.

  3. The same tap now fitted with a thermostatic mixing valve on the exposed copper pipework below

    Controlled

    A result changes something or it changed nothing. Temperature control at the outlet, a dead leg removed, a mixing valve set and logged: that is what a follow-up sample is meant to confirm.

Where this work happens

Five systems, five different questions

A large cooling tower on a flat commercial rooftop at dusk with condenser pipework running to a plant room

Commercial roof

Cooling tower

A hotel plant room with two insulated calorifiers, copper pipework and dial thermometers on flow and return

Hotel plant room

Calorifiers

A hospital corridor handwash basin with a lever tap and a wall-mounted thermostatic mixing valve box

Healthcare

Clinical outlet

A crate of sterile clear sample bottles on a stainless laboratory bench beside a rack of agar plates

Laboratory

Bottles and plates

Insulated copper pipework in a service riser with a dead leg blanked off and a temperature sensor on the flow pipe

Service riser

Dead leg

The system, not the sample

Sampling measures one point on one day. Control is a set of conditions held all year: temperature at the outlets, no stagnant branches, a tower cleaned on a schedule someone signs. A programme built on results alone reacts; a programme built on conditions prevents.

What a programme has to cover

Three questions that come up every time

How many sampling points does a building need?

There is no general answer, and anybody who gives you one has not seen your building. It depends on the size and complexity of the system, the occupancy, what your programme specifies, and what previous results showed. It is settled on the schematic, as described under water management programmes.

Is a test kit good enough?

For watching a trend between scheduled samples on a system already under a documented programme, sometimes yes. If a decision rests on the number, it rests on culture. The trade-off is set out in the advice section.

Someone in the building is unwell. What do I do?

Contact a doctor and your local health department before you contact us. They will tell you what sampling they want, when, and by whom, and sampling ahead of that instruction can complicate an investigation rather than help it. What we do in that situation is on urgent requests.

All frequently asked questions