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2nd Amendment to the Drinking Water Ordinance (TrinkW)

On 14 December 2012, the 2nd Directive on Amending the Drinking Water Ordinance (TrinkwV) came into force. This sets out a number of amendments and clarifications compared to the 1st Directive on amending the Drinking Water Ordinance, from 3 May 2011, especially with regard to tests for legionella.

2nd Amendment to the Drinking Water Ordinance

The following information is also available as a customer information sheet that you can download from our download area .


Each year, at least 20,000–32,000 people in Germany become ill with lung infections caused by legionella. Up to 15% of the cases are fatal. Added to this are 10 to 100 times as many cases of pontiac fever, which is also caused by legionella, but which has milder effects. In no way is it acceptable to restrict ourselves to only introducing technical measures once legionella occur, and to avoid undertaking preventative tests to recognise the possible risk. This last instance means being prepared to accept that people will become sick and die from this important water-related infection disease. After all, our own internal tests (< 3,000) have shown that every second sample is legionella-positive and that every fifth sample exceeds the technical measure value.

Reporting obligation/Inspection obligation

The previous obligation to notify the authorities of possession of large systems for heating drinking water, which are used to issue water for commercial (= renting) but not public purposes has been withdrawn. For these types of buildings, the obligation to carry out tests has been reduced from annually to at least every three years. However, the results must be voluntarily made available to the relevant health authority if the technical measure value is exceeded. The first inspection must now take place no later than 31/12/2013 – instead of 31/10/2012. Furthermore, the term ‘large systems’ has been more precisely defined and integrated into the Drinking Water Ordinance. “A large system for drinking water heating is defined as a system with storage drinking water heating or central flow-through drinking water heating, in each case with a content of more than 400 litres, or more than three litres’ content in at least one pipe between the drinking water heater’s outlet and the taps. Any possible circulation pipe is not taken into account in these calculations. Such systems in buildings housing one or two families are not regarded as large systems for drinking water heating.” (Source: section 3, no 12 of the TrinkwV). Property owners and landlords, but also people managing buildings of residential flats for rental, are still obliged to actively implement the new regulations.

Technical measure values

The newly introduced technical measure value for legionella remains 100 CFUs/100ml. However, further measures are only required if this value is exceeded (so from 101 CFUs/100ml). Previously, technical measures were necessary when the technical measure value was reached. If, however, this value is exceeded in a drinking water installation, this is generally a reliable indication that there are avoidable technical faults in either the drinking water installation or how it is operated.

Sample points

In conjunction with adherence to the technical measure value, it is made clear that a random sample is not sufficient to be able to establish whether there is a possible legionella contamination. Section 14 of the TrinkwV therefore stipulates that systemic inspections must be made at multiple representative sampling points. It refers to the sampling scheme set out in the DVGW’s technical rules (worksheet W 551), in conjunction with current Federal Environment Agency) UBA recommendations. According to this, the water heater’s outlet, the circulation’s return flow and every end pipe must be sampled and analysed. In certain cases, not every riser needs to be sampled, but technical hygiene expertise is however necessary before the scope of sampling can be reduced. The business operator must also ensure that appropriate sampling points are fitted with suitable means of sample withdrawal (taps) in accordance with generally recognised technological standards. Furthermore, the nature of the sampling is also set out. You must also not extract the water samples yourself.

Inspection centre

The inspection centre contracted for taking and analysing the samples must be listed in a current publicly available state list, in accordance with section 15, paragraph 4, and must meet the criteria set out there. This approval then applies across Germany. The Institut Kirchhoff Berlin GmbH is accredited to DIN EN ISO/IEC 17025:2005 and named in the list, in accordance with section 15, paragraph 4 of the TrinkwV. Not only can the institute determine legionella, but also all other parameters contained in the Drinking Water Ordinance, as well as expert sampling and provision of expert advice.

Findings of legionella

If the findings of legionella exceed 100 CFUs/100ml, the client must notify the respective health authority within two weeks of receiving the results. Legionella findings equal to or smaller than 100 CFUs/100ml must not be reported. In the event that the technical measure value is exceeded, the owner is obliged to act without delay, without being asked to do so by the responsible health authority.

The cause must be dealt with by an on-site inspection of the affected drinking water installation, in order to assess the danger and also to check whether generally recognised technological standards have been applied. The resulting technical measures required must be carried out on the basis of recommendations of the Federal Environment Agency and in accordance with recognised technological rules. Furthermore, affected tenants must also be informed immediately in a suitable form (for example, a sign).

Measures required if the technical measure value is exceeded

The measures depend on the extent of the legionella contamination. In principle, assessment is on the basis of the least favourable findings. In the event of findings up to 1,000 CFUs/100ml, the DVGW’s worksheet W 551 requires further tests to be carried out at different sampling points within 4 weeks. In the event of findings of up to 10,000 CFUs/100ml, the further tests detailed above must be undertaken immediately and decontamination must be considered. If findings exceed 10,000 CFUs/100ml, a direct emergency response and decontamination are required.

A direct emergency response would involve usage restrictions (eg showers forbidden), or the installation of special filters in shower heads, as well as disinfection. Disinfectation can occur by thermal or chemical means, as well as by UV radiation. Thermal disinfection involves every tap being opened for at least three minutes while a temperature of at least 70° is reached. A week after successful disinfection, further tests must be carried out. In order to monitor the success of decontamination measures, two further inspections must be carried out, in each case after three months. If, despite renewed disinfections, similarly high contamination levels are determined after these shorter intervals, wider-ranging renovation of the system, whether by operational or constructional measures, becomes unavoidable.

Sanctions for breaches of the Drinking Water Ordinance 

Whoever intentionally or negligently breaches the inspection, recording or informational requirements, or who does not properly maintain or operate his or her drinking water supply system, commits an offence under section 25 of the TrinkwV. Furthermore, the intentional or negligent provision of microbiologically or chemically contaminated drinking water also represents a criminal offence under section 24 of the TrinkwV.

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