Legionella Sampling
Purpose
To collect water samples for Legionella testing, keeping the sample clean from collection to the lab.
Required Equipment
Clean 1L sample bottles (with sodium thiosulphate), cool box with ice packs, chain of custody forms, marker pens
Required PPE
Gloves, apron
Required Tools
Sample bottles, cool box, ice packs, labels, chain of custody forms, pen
Step-by-Step Method
- Pick the right tap - use a normal tap, not a mixer valve. Sample before the mixer if you can.
- Remove any attachments (shower heads, aerators, flexible hoses).
- Put on gloves.
- Label the bottle with date, time, location, tap name, and your name.
- Run the water for 2-3 seconds only. Do NOT flush for a long time.
- Open the bottle and hold it at an angle so you do not touch the tap.
- Fill to the neck, leaving some space at the top.
- Cap it right away and tip gently to mix with the sodium thiosulphate.
- Put in cool box with ice packs (keep at 2-8 degrees C - do NOT freeze).
- Fill in the chain of custody form.
- Get it to the lab within 24 hours.
- Write down what you did in the site records.
Pass Criteria
Sample at the lab within 24 hours at 2-8 degrees C. Chain of custody form complete. Bottle labelled correctly. No contamination.
Fail Criteria
Sample arrives after 24 hours. Temperature outside 2-8 degrees C (frozen or warm). Chain of custody incomplete. Bottle not labelled or contaminated.
Common Problems & Corrections
False low results - Caused by flushing too long before sampling. Only run for 2-3 seconds. False high results - Cross-contamination from touching the tap or bad bottle handling. Lab rejects sample - Temperature wrong or delivery too late. Plan your logistics. Chlorine not stopped - Make sure the bottle has sodium thiosulphate for chlorinated systems. Mixer valve samples misleading - Sample before the mixer valve where possible.