August 6, 2026 · 4 min
If you are looking for a diagnosis, this is the wrong website
Around 480 people a month search for legionella disease testing. Most of them need a doctor, not a water sampler. Here is the difference, said plainly.
We test water. We do not test people, we do not diagnose anything, and we are not clinicians. If you arrived here because you are worried about someone’s health, the correct next step is a doctor or your local health department, and it is a more urgent step than anything on this website.
That is the whole of the advice. The rest of this article exists because the two kinds of testing get confused, and the confusion wastes time that occasionally matters.
Clinical testing is done on a person
Diagnosing an infection is a medical procedure carried out on a patient by a healthcare provider, using clinical specimens, ordered and interpreted by a clinician. It answers the question of whether a specific person has a specific infection.
We have no role in that. No sample we take, and no report we write, is capable of answering it. Nothing on this site should be read as medical advice, and no result we issue tells anybody anything about their health.
Environmental testing is done on a building
Sampling a water system answers a different question: whether the organism is present and growing in a particular part of a particular system at a particular moment. Which part is sampled decides what the answer covers, as set out in where to sample in a building. It informs how the building is operated and maintained, through the programme described in what a water management plan contains.
That is our work, and it is described under testing services. What one of our results establishes, and the longer list of things it does not, is in what a legionella test tells you.
Where the two genuinely meet, and who leads
When a clinician identifies a case, public health authorities may investigate possible environmental sources, and environmental sampling can be part of that investigation. In that situation the investigation is led by the health authority, not by a facility and not by a laboratory the facility has retained.
If a case has been associated with a building you are responsible for, the first call is to your local health department. They will tell you what sampling they want, when, and by whom. Sampling ahead of that instruction can complicate an investigation rather than help it.
What we will do if you call us in that situation
Tell you to contact the health department first, and then do exactly what they ask, on their timetable, with the chain of custody they require. We will not offer an opinion on whether a building caused an illness, because that is not a question sampling can answer on its own.
Urgent environmental sampling, when it is what has been asked for, is described under urgent requests.
If your question is about a building, we can help
If it is about a person, please contact a doctor or your local health department first.
Legionella Screen samples building water systems and cooling towers and has the samples analysed by culture in an accredited laboratory. It does not diagnose illness, does not treat anyone, and gives no medical advice of any kind.