Drinking Water Regulation

Drinking Water Ordinance - The Drinking Water Ordinance (TrinkwV) sets forth the quality requirements for drinking water in Germany and the obligations of operators of drinking water systems. It transposes EU drinking water directives into national law and protects consumers from water that is harmful to health. For property owners, the obligation to conduct Legionella testing in multi-unit residential buildings with central hot water systems is particularly relevant, as owners must take action and are liable if the limit values are exceeded.

Legionella Testing Requirement for Landlords

The Drinking Water Ordinance requires owners of multi-family buildings with centralized hot water systems to conduct an annual Legionella test if the storage tank capacity exceeds 400 liters or the volume of water in the piping between the heating system and the tap exceeds 3 liters. The testing must be performed by a testing laboratory accredited according to DIN EN ISO 17025.

Limit value: 100 colony-forming units per 100 ml (CFU/100 ml) - if this limit is exceeded, the owner must:

1. Immediately notify the public health department
2. Have a risk assessment conducted by a certified specialist company
3. Implement immediate measures (thermal disinfection, flushing the pipes)
4. Permanently eliminate the causes

Legionella are bacteria that multiply rapidly in warm, stagnant water (25-50 °C). Inhaling aerosols containing Legionella while showering can lead to severe pneumonia (Legionnaires’ disease)-a condition with a significant mortality rate among older or immunocompromised individuals.

Owner’s Obligations

In addition to Legionella testing, the owner of a rental property has further obligations under the Drinking Water Ordinance (TrinkwV):

Reporting Requirement: When a new drinking water system is put into service for the first time or undergoes a significant modification (e.g., renovation of the hot water system, installation of new pipe sections), the system must be reported to the Public Health Department.

Use of Approved Materials: Only materials that meet the requirements of the DVGW regulations and DIN 1988 may be used in drinking water systems (e.g., copper, stainless steel, plastic approved for drinking water). Galvanized steel pipes for hot water are no longer permitted-in older buildings (built before approximately 1970), such pipes may still be present and must be replaced during renovation.

Documentation requirement: Results of Legionella tests, maintenance records for hot water systems, and documentation regarding the piping system must be retained. In the event of damage, the owner must be able to prove that they have fulfilled their obligations.

Violations may result in fines of up to 25,000 euros per violation and, in the event of damage-if a tenant contracts Legionnaires’ disease-personal liability under Sections 823 et seq. of the German Civil Code (BGB).

Measures to Take in Case of Elevated Legionella Levels

If the threshold value is exceeded, the following measures must be taken step by step:

1. Immediate Measures: Notify the health department; if necessary, issue a shower ban; install end-of-line filters on showerheads (as a temporary measure)
2. Thermal Disinfection: Flush all pipes for at least 3 minutes with water above 70 °C - Legionella bacteria are killed at temperatures above 60 °C, and reliably and quickly at 70 °C
3. Risk analysis: Systematic inspection of the system to identify vulnerabilities (dead-end pipes, storage tank temperature too low, stagnant areas)
4. Long-term remediation plan: Elimination of identified vulnerabilities (e.g., removal of dead-end pipes, raising the hot water storage tank temperature to at least 60 °C, circulation optimization)

The cost of thermal disinfection ranges from 300-800 euros for an average apartment building; a risk assessment costs 500-1,500 euros.

Practical Tip for Property Owners in Nuremberg

We recommend that owners of apartment buildings in the Nuremberg metropolitan area have Legionella testing performed in a timely manner by an accredited laboratory and report the results to the Nuremberg Public Health Department within the required timeframe. The cost is approximately 200-400 euros per test, depending on the number of sampling points (typically 1 per 400 liters of storage volume, but at a minimum at the hot water inlet, outlet, and the most unfavorable sampling point).

If elevated levels are detected: Do not panic-thermal disinfection effectively eliminates Legionella in most cases. In the long term, the hot water system should be inspected for vulnerabilities: Dead pipe runs (pipe ends with no flow), storage tank temperatures that are too low (below 60 °C), and stagnant water in rarely used pipe sections are the most common causes. Such vulnerabilities are particularly common in post-war buildings in Nuremberg-proactive management protects tenants and minimizes liability risk.

Frequently Asked Questions

Does the Legionella testing requirement also apply to single-family homes?

No, single-family homes and two-family homes are exempt from the testing requirement, as the Drinking Water Ordinance (TrinkwV) applies only to systems operated as part of a commercial or public activity. A rented granny flat counts as commercial use-here, the requirement may apply if the system exceeds the threshold values (storage tank >400 liters or pipe volume >3 liters). In case of doubt, the responsible public health department will determine whether a testing requirement exists. Owners who are unsure should contact the Nuremberg Public Health Department for informal guidance.

What to do in case of Legionella contamination?

If values exceed 100 CFU/100 ml, the health department must be notified immediately. The owner must have a risk assessment conducted by a licensed specialist company, identify the cause, and take appropriate measures. If values exceed 10,000 CFU/100 ml, there is an acute health hazard-in this case, the health department may issue a shower ban or order the installation of end-of-line filters. As long as the shower ban is in effect, the landlord is generally not permitted to rent out the affected units or must take measures to eliminate the risk.

Can the costs be passed on to the tenants?

The costs of regular Legionella testing are apportionable as operating costs (Section 2 No. 2 of the Operating Costs Regulation (BetrKV) - costs of water supply and system inspection). This is subject to the condition that the lease agreement contains a corresponding operating costs clause. Costs for the elimination of Legionella contamination-i.e., thermal disinfection, pipe renovation, risk analysis-are, however, maintenance costs and must be borne by the landlord; they may not be passed on to the tenants. The lease agreement should clearly stipulate the apportionability of testing costs to avoid billing disputes.

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