Calibration law for water and heat meters

Calibration law for water and heat meters

In Germany, calibration is mandatory. This obligation is regulated via the Measurement and Calibration Act (MessEG) in the version of July 25, 2013 (BGBl. I p. 2722), last amended on April 11, 2016 (BGBl. I p. 718) and in the Measurement and Calibration Ordinance (MessEV) of December 11, 2014 (BGBl. I p. 2010), last amended on August 10, 2017 (BGBI. I p. 3098), which is based on it.
The aim of this law is to protect consumers when purchasing measurable goods in the course of business.

Commercial transactions are understood as the use of measuring devices with which heating, hot water and cold water costs are billed. The basis for billing is the meter reading. All measuring instruments used in business must be calibrated.

A Notified Body, such as the Physikalisch-Technische Bundesanstalt (PTB), checks whether a measuring instrument meets the legal requirements. Among other things, the measurement accuracy and the measurement stability are checked. The type approval is certified with a certificate. All measuring devices of this type must comply with the characteristics described here.

Before a measuring device may be used, it must be calibrated. This means that the measuring instrument is adjusted under precisely defined conditions and checked for compliance with the calibration error limits.

In the past, all measuring instruments in Germany were calibrated by calibration offices or state-approved testing laboratories. In the course of harmonization in Europe, a European Measuring Instruments Directive (MID) was created, which allows manufacturers to declare the conformity of the devices themselves. The declaration of conformity is considered equivalent to a calibration. In order for a manufacturer to be allowed to declare the conformity of his equipment, he must undergo certification by a Notified Body (e.g. PTB). During this certification, the manufacturer’s quality management system is checked and it is further verified that the manufacturer can produce and calibrate the measuring instruments with the required accuracies. Annual audits ensure consistent quality.

In Germany, the MessEV regulates how long a measuring device may be used. The calibration validity (calibration period) is 5 years for heat meters and hot water meters and 6 years for cold water meters. The calibration period begins at the end of the year in which the meter was calibrated. This means that a heat meter that was calibrated in April 2018, for example, must be replaced by the end of 2023.


A conformity marking is affixed to each calibrated device. This labeling includes:

  • a CE mark
  • the year of the year in which the meter was manufactured
  • the number of the Notified Body that performs the quality audits at the manufacturer’s premises
  • the number of the type approval

In general, the calibration period begins with the year of marking. In exceptional cases, however, equipment may not be placed on the market until the following year. The calibration period then begins later and must be supported by the original manufacturer’s delivery bill including serial numbers.


Anyone who intentionally or negligently uses non-calibrated equipment in commercial transactions commits an administrative offense. This can be punished with fines of up to €10,000 in accordance with the MessEG (§60 Para. 2).


  • The notification requirement states that the following data must be reported on the website within 6 weeks of commissioning:
  • The type of device
  • the manufacturer
  • the type designation
  • the year of calibration
  • the address of the user
  • Ensure that settlements are made only with calibrated equipment and that equipment is replaced with new equipment before the calibration period expires.

Nico Hartig
Ing. metrological Department
Engelmann Sensor GmbH
Rudolf Diesel Street 24-28
69168 Wiesloch-Baiertal
Tel.: +49 6222 98 00 594
Fax: +49 6222 98 00 50

Ulrich Kunstein
Dipl. Ing. Head of metrological Department
Engelmann Sensor GmbH
Rudolf Diesel Street 24-28
69168 Wiesloch-Baiertal
Tel.: +49 6222 98 00 46
Fax: +49 6222 98 00 50

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