Corresponding paperwork must be completed for each sample taken containing the same information as above.
Corresponding paperwork may also contain the following information:
Sufficient detail to enable sample to be taken from the same location;
Unusual features when taking the sample, i.e. smell, appearance or flow rates.
1.3.2 Sampling Procedure
Samples only to be taken using an un-tampered sterile bottle.
Single use disposable gloves are to be worn. A new pair will be worn for each sample taken and disposed of immediately after the sample has been taken. The disposable gloves shall be kept in their original supplied packaging until the time when they are required [ensure the user is not sensitive to the disposable gloves supplied].
Pre flush sample shall be taken (regardless of sampling for Legionella or bacteriological). The outlet will not be disinfected prior to taking the sample. The sample of water will be taken without letting any water run to waste. (This type of sample is most representative of the risk to individuals and is the only sample that should need to be taken from systems where there is evidence of adequate, sustained control and low risk).
Post flush samples shall be taken (regardless of sampling for Legionella or bacteriological).
Sample taps are disinfected before being sampled. Disinfection methods by using a 1 in 10 dilution of a commercial grade sodium hypochlorite solution (containing in the range 12% to 14% available chlorine Sodium hypochlorite solution.
The outlet shall be disinfected in accordance with BS7592:2008.
Flaming method is not to be used.
When taking samples the bottle is held in one hand and the bottle cap removed with the other hand, ensuring the top or the neck of the bottle doesn’t come in contact with hands or the outlet.
Do not rinse out the bottle or the cap.
Do not place the cap on any surface, it should remain in your fingers.
Turn on the water so a gentle stream is flow, fill the bottle leaving a small air gap at the top, do not allow to over flow.
Replace bottle cap immediately taking care not to touch the top or the neck of the bottle.
The bottle should then be placed into a cool, dark, insulated container for transporting to the laboratory (see below for more detail).
Sample delivery times to the laboratory:
Legionella samples within 24 hours but no more than 48 hours.
Bacteriological samples should be as soon as possible, not exceeding 24 hours if stored correctly (see below).
Transportation of sample:
Legionella samples should be protected from heat and sunlight, kept at ambient temperature not exceeding 20OC. Hot and cold samples to be packaged separately.
Bacteriological should be kept in dark, insulated storage containers which are regularly disinfected. The temperature of the sample should be kept at 2-8OC.
If during sampling accidental contamination is suspect the sample should be discarded and a fresh sterile bottle used to take a new sample.
a) If limited outlets or count 20-40 = Re-sample at once, and disinfect if repeated again.
b) If more than 20% of outlets or counts 40+ disinfect at once, and review procedures.
TVC, E.coli, coliforms
Representative outlets as agreed with the consultant (specify)
TVC = >100
E.coli = >0
Coliforms = >0
a) If limited outlets give TVC counts of 100-500 then re-sample at once. If similar results from second sample then disinfect tank and system.
b) If more than 20% of outlets give TVC counts 100+ disinfect at once, and review procedures.
c) If TVC results give counts >500 sample the mains cold water unit a clear result is achieved. Then sample the cold water storage tanks, if these results are clean then no further action. If the results are returned positive then clean the cold water storage tank.
Re-sample. Disinfect if fail.
Disinfect at once and review systems.
TVC, E.coli, coliforms
1 MCW
1 of each Tank
2 TCW taps
2 DHWS taps
TVC = >100
E.coli = >0
Coliforms = >0
a) If limited outlets give TVC counts of >100 = Re-sample at once, and disinfect if repeated again.
b) If more than 40% of outlets give TVC counts 100+ disinfect at once, and review procedures.
c) If TVC results give counts >500 sample the mains cold water until a clear result is achieved. Then sample the cold water storage tanks, if these results are clean then no further action. If the results are returned positive then clean the cold water storage tank.
d) If any outlet returns E.coli or coliforms of >0 disinfect.
LOW
(e.g. staff areas)
LEGIONELLA
(species and numbers)
1 MCW
1 of each Tank
2 TCW taps
2 DHWS taps
>100
>1000
Re-sample. Disinfect if fail.
Disinfect at once and review systems.
TVC, E.coli, coliforms
1 MCW
1 of each Tank
2 TCW taps
2 DHWS taps
TVC = >150
E.coli = >0
Coliforms = >0
a) If limited outlets give TVC counts of >120 = Re-sample at once, and disinfect if repeated again.
b) If more than 40% of outlets give TVC counts 120+ disinfect at once, and review procedures.
c) If TVC results give counts >500 sample the mains cold water until a clear result is achieved. Then sample the cold water storage tanks, if these results are clean then no further action. If the results are returned positive then clean the cold water storage tank.
d) If any outlet returns E.coli or coliforms of >0 disinfect.
(*) These are for guidance. The risk assessment will indicate need to disinfect as a combination of factors may need to be considered.
Samples for Legionella shall be tested by a UKAS accredited laboratory that takes part in the HPA Water Microbiology External Quality Assessment Scheme for the isolation of Legionella from water.
