Drinking Water Ordinance: duties for operators and landlords
The Drinking Water Ordinance of 20 June 2023 makes the operator of a water supply system responsible. For buildings, that means: having certain systems tested for Legionella, notifying and resolving abnormal test results, using only permitted treatment substances, commissioning accredited laboratories, and informing consumers. Which duty applies depends on the system and on whether the water is supplied commercially or publicly.
Who is an operator under the Drinking Water Ordinance?
Under Section 2 No. 3 TrinkwV, an operator is "an undertaking or other holder of a water supply system". A building with a drinking water installation is a building water supply system: a system from which drinking water from the public supply is delivered to consumers through a drinking water installation (Section 2 No. 2(e)). The Ordinance also recognises mobile systems, for example on board vehicles, and temporary systems such as at funfairs.
Many duties depend on how the water is supplied:
- Commercial activity is the supply of drinking water as part of a rental or other independent, regular activity carried out for profit (Section 2 No. 8).
- Public activity is the supply of water to an indeterminate, changing group of people not connected by personal relationships (Section 2 No. 9).
What duties does the operator have?
| Duty | When it applies | Reference |
|---|---|---|
| Notification to the health authority: construction, commissioning, material alteration, change of owner, decommissioning | for buildings, only if the water is supplied as part of a public activity; for mobile systems, for commercial or public activity | Section 11 TrinkwV |
| Testing for Legionella | hot-water heaters over 400 litres, or over 3 litres in a hot-water pipe, plus showers or other atomisation, commercial or public supply; not in single- and two-family homes | Section 31 TrinkwV |
| First Legionella test of a new system | within three to twelve months of commissioning | Section 31(4) |
| Only accredited laboratories | for all testing under the Ordinance, including sampling | Section 39(1) |
| Duties at 100 CFU of Legionella per 100 ml | notify without delay, investigate the cause, written risk assessment, measures | Section 51(1) |
| Informing consumers | for Legionella findings, without delay, about the risk assessment and any restrictions on use | Section 52(3) |
| Only permitted treatment substances | for any treatment, including disinfection | Section 19(3), list under Section 20 |
| Informing about treatment | in writing, about the start of use of a treatment substance and its concentration | Section 26(1) |
| Suitable materials | materials in contact with drinking water must not, among other things, promote the growth of microorganisms; organic materials must meet the UBA's assessment basis | Sections 13, 14, 15 |
Source: German Drinking Water Ordinance of 20 June 2023 (in German), read on 21 September 2026. The table summarises and does not replace the wording.
What applies to landlords and property managers?
Under Section 2 No. 8, renting out property is a commercial activity. If the rented building meets the criteria of Section 31, that is, a hot-water heater of more than 400 litres or more than 3 litres in a hot-water pipe, plus showers, the operator must have the drinking water tested for Legionella at least every three years. Single- and two-family homes are exempt.
If a test result of 100 CFU per 100 ml or more is found, the duties under Section 51 apply: notify, investigate the cause, risk assessment, measures, and inform tenants under Section 52. The individual steps are described on the page Positive Legionella result: what to do now.
What applies to schools, hospitals and other public facilities?
If drinking water is supplied as part of a public activity, Legionella testing applies at least once a year, provided the criteria of Section 31 are met. After three consecutive years without an adverse finding, the health authority can extend the interval to up to three years (Section 31(3)). This does not apply to facilities under Section 23(5) of the Infektionsschutzgesetz (German Infection Protection Act), care facilities, and facilities with patients who have a higher risk of Legionella infection. The duty to notify under Section 11(1) also applies to public buildings.
What applies to mobile and temporary systems?
Under Section 2 No. 2(d), mobile systems are movable systems, including systems on board land, water and air vehicles. There, the duty to notify under Section 11 and the Legionella testing under Section 31 are tied to a commercial or public activity; the health authority sets the testing frequency. A rented-out motorhome therefore falls under commercial activity; a vehicle used purely privately, in our assessment, generally does not. However, the Legionella testing under Section 31 only applies if the criteria for volume and showers are also met.
Temporary systems, such as the drinking water supply at funfairs, must be notified to the health authority as early as possible. The related DVGW guidance is described on the page Drinking water hose and the page Flushing and disinfection.
Frequently asked questions on the Drinking Water Ordinance
Must I, as a landlord, have the drinking water tested for Legionella?
Yes, if the system meets the criteria of Section 31 TrinkwV: a hot-water heater of more than 400 litres, or more than 3 litres in at least one hot-water pipe, plus showers or other atomisation. Renting out property counts as a commercial activity; testing is due at least every three years. Single- and two-family homes are exempt.
Does the duty to test for Legionella also apply to a single-family home?
No. Section 31(1) No. 3 TrinkwV exempts water supply systems in single- and two-family homes from the testing duty. Anyone who has voluntary testing done there and receives an elevated result is best advised to discuss it with the health authority or a specialist firm.
What must I notify to the health authority?
Under Section 11(1) TrinkwV, among other things: construction, commissioning and recommissioning, material structural or operational alterations, a change of ownership or right of use, and decommissioning. For buildings, this only applies if the drinking water is supplied as part of a public activity. If the technical action value for Legionella is reached, the operator notifies this without delay under Section 51. This only does not apply if the operator holds evidence that the laboratory has already notified the result.
Who may take drinking water samples?
Testing under the Drinking Water Ordinance, including sampling, may only be carried out by laboratories accredited for this purpose (Section 39(1)). The federal states publish lists of these laboratories. More on this on the page Sampling and measurement.
May I add a disinfectant to the drinking water myself?
Under Section 19(3) TrinkwV, only substances from the list under Section 20 may be used in treatment. Anyone treating drinking water informs consumers under Section 26 about the use and the concentration. The UBA list requires a trained person to check the remaining concentration daily for continuous treatment. If the condition of a drinking water installation is the reason why the microbiological requirements are not met, the drinking water there may, under Section 23(3), only be disinfected on the order of the health authority, and the operator must remediate the installation. For disinfecting your own water tank in a motorhome or boat, the dosing instructions apply.
Sources
- Section 2 TrinkwV: definitions (in German)
- Section 11 TrinkwV: notification duties (in German)
- Section 31 TrinkwV: testing for Legionella (in German)
- Section 39 TrinkwV: accredited laboratories (in German)
- Section 51 TrinkwV: measures when the technical action value is reached (in German)
- Section 52 TrinkwV: informing consumers (in German)
- Section 19 TrinkwV: treatment (in German) and Section 26 TrinkwV: information about treatment (in German)
This page does not replace legal advice or guidance from the health authority. The version of the Drinking Water Ordinance in force at any given time is authoritative.