In order to ensure accurate results for Legionnaires’ water testing, it is important that collection process is correct. Here are a few tips for collecting water samples.
If you are collecting water samples in a property where legionella has been recently found, don’t put yourself at risk. Avoid creating an aerosol, do this by running the taps very slowly. For showers or high pressure outlets, use a clean, dry sandwich bag and snip one corner off – place it over the outlet, open it slowly and collect the water as it drains from the bag.
Collecting before and after flush samples
Avoid flushing the water outlets immediately before collecting water samples. Sometimes the legionella bacteria can only be found in the outlets themselves, we call this a pre-flush sample.
If you are trying to determine if legionella are in the distribution pipework, then do a post-flush sample. This involves flushing the outlet for ~ 30 seconds, removing spray inserts, flow directors etc, inject disinfectant (from a wash bottle) inside the nozzle of the tap until it runs out and allow two minutes for the disinfectant process to take place. Finally run the outlet for 2 minutes before collecting the water sample.
Use the right type and amount of neutraliser
The bottles we supply contain small amounts of sodium thiosulphate to neutralise chlorine and other halogens present in the water. If you are treating your water with copper/silver ionisation let us know and we will supply sterile bottles with a chelating agent.
Collecting swab samples
Collect swab samples from areas where there is a build-up of scale. You will first need to pre-wet the swabs using water from the sampling site. You will also need to collect slime, sludge and sediment.
Measuring water temperature
Always measure the temperature of the water sample, the laboratory require this information. Simply place a thermometer in the water stream and note the reading. (Don’t let the thermometer come in contact with any water in the sample bottle). Once you are done in one area, sanitise the thermometer using isopropyl alcohol in order to prevent cross-contamination.
Complete the submission sheet
It’s vital that the laboratory know where the sample was taken from and also the time it was taken.