Tapping points for drinking water heating systems with circulation (see also ÖNORM B 5019/B 1921)

• a sample at the point where the circulation pipe joins the drinking water heater (TWE). A sampling facility must be provided at this point
• a hot water sample at a suitable point for taking storage tank water (preferably in the lower third or at the storage tank draining device; possibly also at the temporarily shut-off cold water supply pipe)
• Depending on the size of the system, several samples (hot water and cold water) from the supply network, showers or other tapping points, whereby distant and rarely used tapping points should also be sampled. In healthcare facilities, outlets in risk areas should be specified for sampling (e.g. intensive care units, showers for people with weakened immune systems)

In the case of more extensive tests or if necessary, further sampling points and the number of samples must be determined on a problem-specific basis in consultation with an expert familiar with the system.

Sampling points for cold water distribution systems

In the case of large cold water distribution systems, systems in which the cold water heats up due to poor thermal insulation in the pipes or pipes with stagnation, cold water samples from peripheral sampling points must be analysed.

Sampling points for pool baths including whirlpools

The pool water and the water from the water treatment system must be analysed before chlorination.

Tapping points for hot whirlpool tubs

Tub water must be analysed after five minutes of empty operation. When empty, a hot whirlpool tub must be filled with warm water as intended for a bathing process and operated with all massage devices and water and air flows without the use of persons. For more extensive examinations, filling water or heated drinking water must also be taken from a nearby tap.

Sampling points for evaporative recooling systems

Samples should preferably be taken from the circulation water between the running pump and spraying/spraying. A sampling point must be provided at this point. If sampling is not possible at this point, a sample can be taken either directly under the spraying device or as an immersion sample from the sump.

The amount of water required for the test should always be agreed with the respective institute carrying out the tests. Sterile bottles with screw caps are recommended as sample containers. If the water is chlorinated, bottles with added sodium thiosulphate (18 mg/l) should be used.

If the tap has a scalding protection (thermostat) or if this has been deactivated, this fact must be indicated on the sample label. The water temperature is measured and documented when the constant temperature is reached. If it takes an unusually long time to reach constancy, the time required is also recorded.

The sample must be adequately labelled. Water samples must always be accompanied by a carefully and completely filled out accompanying certificate.

Sampling for drinking water heating systems

(see also ÖNORM B 5019 /B 1921)

Routine checks are carried out under normal operating conditions and not during a heating phase. Water samples from peripheral tapping points are taken after brief draining (approx. 15 seconds fully open) without unscrewing shower heads or aerators and without flaming. The conditions are therefore the same as those usually encountered by users when drawing water (showering, washing hands, brushing teeth, etc.).

In order to clarify the question of whether there is a systemic contamination of the drinking water heating system with Legionella or whether there is only a problem in a peripheral pipe or a fitting, additional water samples can be taken from an outlet immediately and after allowing the water to drain for at least 1 minute after the temperature has stabilised.

If samples are taken from the storage tank, it must be ensured that the sample is not falsified by stagnant water from the outlet pipe.

Sampling for cold water distribution systems

If hot water is also analysed at the tap, the sample should only be taken after the heated drinking water has been sampled. After fully opening the cold water outlet, the sample is taken after approx. 15 seconds for routine tests. Depending on the distribution system, other times may also be appropriate for more extensive tests.

Sampling for pool baths including whirlpools

(see also Bathroom Hygiene Ordinance 2012 as amended)

Pool water must be taken as a scoop sample 5 to 20 cm below the water surface and 30 to 50 cm from the edge of the pool. Samples from the water treatment system before chlorination should be taken from a suitable sampling tap after flaming and prolonged draining of water.

Sampling from medical-technical devices

This includes, for example, dental treatment units, ENT units and other rinsing units.

For the purpose of routine control, water should be collected under normal operating conditions and after repeated use. Sampling is carried out directly at the outlet in the same way as the water is used on the patient, i.e. without draining, rinsing or flaming.

Sampling for hot whirlpool tubs

(see also Bathroom Hygiene Ordinance 2012 as amended)

The water sample must be taken 5 to 20 cm below the water surface in the centre of the tub at the end of empty operation. During empty operation, the tub is filled as for a normal bathing process and all bubble devices are operated for at least 5 minutes.

Sampling for evaporative recooling systems

(see also ÖNORM B 5020 )

Sampling must be carried out under normal operating conditions and not shortly after the time of intermittent biocide dosing. In the case of continuous biocide dosing, the sample must be taken upstream of the dosing point.

The sample is preferably taken from the circulating water between the running pump and spraying/spraying from a suitable sampling tap after flaming and prolonged draining of water (at least 30 seconds). If this is not possible, water from under the spraying device or from the tank can also be used for sampling. Biocide residues in the sample must be neutralised immediately during sampling.

Transport and storage of samples

After sampling, the samples must be transported to the test centre as soon as possible. If transport takes place within 12 hours, no refrigeration is required. For storage times of 12 to 24 hours, the samples must be kept refrigerated.

The samples must be processed within 24 hours of collection.

The interpretation of the results of Legionella tests is complex because the measured concentrations of Legionella do not directly reflect the actual risk to people. This is due on the one hand to the very large differences in virulence of the various Legionella strains, and on the other hand to the type of exposure possibilities and the resistance of the exposed persons. If it is suspected that the system has been a source of infection, sanitation measures are required even if low concentrations of Legionella are detected.

In terms of virulence (sum of the pathogen's pathogenic and aggressive properties), strains of Legionella pneumophila serogroup 1 are generally to be classified as more critical than other serogroups of Legionella pneumophila and other Legionella species.

The hygienic assessment of the results from the test reports must be carried out by an expert. Indications for the assessment and the resulting measures are provided by

• ÖNORM B 5019 or ÖNORM B 1921 for drinking water heating systems
• for swimming pools including whirlpools, the Bathroom Hygiene Ordinance 2012 as amended.
• ÖNORM B 5020 for evaporative recooling systems
• for medical-technical devices the Medical Devices Act 2021 as amended.

Institute of Medical Microbiology and Hygiene, Vienna
Centre for Anthropogenic Infections

Währinger Straße 25a | 1096 Vienna
Phone: +43 (0)5 0555-37111
Fax: +43 (0)5 0555-37109
E-mail: wasser.wien@ages.at

Delivery times at the institute: Mon - Thu: 08:00 - 15:00, Fri: 08:00 - 11:00 (except public holidays)

Institute for Medical Microbiology and Hygiene, Graz
Centre for Foodborne Infectious Diseases

Beethovenstraße 6 - 8 | 8010 Graz
Phone: +43 (0)5 0555-61202
Fax: +43 (0)5 0555-61110
E-mail: lebensmittel.graz@ages.at

Delivery times at the institute: Mon - Thu: 07:30 - 14:30, Fri: 07:30 - 12:00 (except public holidays)

Institute for Hydroanalysis, Linz

Wieninger Straße 8 | 4021 Linz
Phone: +43 (0)5 0555-41611
Fax: +43 (0)5 0555-41605
E-mail: hydroanalytik@ages.at

Delivery times at the institute: Mon - Thu: 07:30 - 15:00, Fri: 07:30 - 13:00 (except public holidays)

Samples that are to be analysed for Legionella in accordance with the Epidemics Act must be sent directly to the Institute for Medical Microbiology and Hygiene Vienna.