Legionella
Culture testing for Legionella species, including Legionella pneumophila, the main cause of Legionnaires' disease.
Legionella water sampling & testing
Sampling gives you laboratory proof that your control measures are working. Our engineers take samples the right way, from the right outlets, and we explain the results in plain English, along with exactly what to do if anything comes back high.
What we test for
Laboratory analysis we arrange
Total viable counts (TVC)
A general measure of bacterial activity in the water, used to spot problems in tanks and systems early.
E. coli & coliforms
Indicators of contamination, used for drinking water checks and after tank cleaning or disinfection.
Pseudomonas aeruginosa
Required in augmented care areas in hospitals under HTM 04-01, where patients are most vulnerable.
Dental unit waterlines
Microbial testing of dental waterlines to support HTM 01-05 compliance and CQC inspections.
Post-disinfection checks
Samples after chlorination or tank cleaning to confirm the system is clean before it goes back into use.
When is sampling needed?
Sampling isn't always required, but sometimes it's essential
Your assessment says so
Where temperature control is hard to achieve, or where users are particularly vulnerable.
Healthcare & care
Routine sampling in hospitals, augmented care and some care settings, as part of the Water Safety Plan.
After works or a positive result
To confirm disinfection has worked, or to track a system back to safe levels.
Investigating a concern
Complaints about water quality, a suspected case, or a system that's been out of use.
Understanding results
What your Legionella results mean
A simplified summary of the HSE's suggested actions for hot and cold water systems (HSG274 Part 2). We'll interpret your results for your specific site.
| Result (cfu per litre) | What it suggests | What happens next |
|---|---|---|
| Not detected / under 100 | Controls are working | Carry on with your monitoring programme |
| 100 to 1,000 | Control may be slipping, especially if several samples are positive | Resample, review your control measures and risk assessment, and fix any problems found |
| Over 1,000 | Significant colonisation | Resample urgently, review controls straight away, and consider disinfection of the system |
A summary only. Always follow the advice for your site, and act sooner if users are vulnerable.
Done properly
How we sample
Planned sampling points
We choose outlets that represent your system: sentinels, high-risk areas and anywhere your assessment flags.
Correct technique
Pre- and post-flush samples where needed, sterile bottles, neutralising agents for chlorinated water, and temperatures recorded.
Chain of custody
Samples kept cool and delivered to the laboratory with full paperwork, within the required time.
UKAS-accredited labs
Analysis by UKAS-accredited laboratories, so results stand up to scrutiny.
Clear results
We explain what the numbers mean and what, if anything, you need to do.
Joined-up follow-up
If results are high, the same team can arrange disinfection, remedials and resampling.
FAQs
Water sampling questions
Does a negative result mean my water is safe?
Not on its own. A sample is a snapshot of one outlet at one moment, and Legionella can be present elsewhere in the system. That's why sampling supports a risk assessment and monitoring programme rather than replacing them.
How long do results take?
Legionella is cultured in the lab, so results usually take around 10 days. Tests such as TVC and coliforms are quicker. We'll let you know as soon as results are in.
Do landlords need to test for Legionella?
Not usually. For most rented homes, the HSE doesn't expect routine sampling. A good risk assessment and simple controls are enough. We'll only recommend sampling if there's a real reason for it.
How many samples will I need?
It depends on the size of the system and why you're sampling. We'll recommend the number and location of samples when we quote.
Related services
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From the blog
Related articles
Legionella in care homes, schools and dental practices
Care homes, schools and dental surgeries each have their own Legionella risks. What's different about each and what inspectors tend to look for.
Positive Legionella sample result: what happens next?
A positive Legionella result is worrying but manageable. What the numbers mean under HSG274, who to tell and how to get the system back under control.
Reopening a building after closure: getting the water safe
Water that's sat still for weeks is a Legionella risk. A practical guide to flushing, checks and sampling before you reopen an office, shop or school.
Need water samples taken?
Tell us about your site and why you need sampling, and we'll recommend the right tests and quote.