The quality of tap water is regulated by the Drinking Water Ordinance. This specifies which chemical, biological, and physical parameters must be tested at regular intervals. There are two suppliers for the Mainz city area. Mainzer Netze GmbH supplies all districts except Laubenheim and Ebersheim, which are served by Wasserversorgung Rheinhessen-Pfalz GmbH. The water suppliers always publish the latest analysis data for their supply area on their websites. You can find these in the list of links below.

In general, the analysis values for the entire city of Mainz are very good. For example, the nitrate values for the area are all well below the limit of 50 mg/l, with 1.5 mg/l for the old town and 5.3 mg/l for Ebersheim. The water hardness, which is an important factor for detergent dosage, for example, is classified as "hard" throughout the city. The only remedy for this is to descale electrical appliances and fittings regularly. In principle, however, the high lime content is not harmful to health.

The Drinking Water Ordinance applies up to the house connection; after that, compliance with quality standards is the responsibility of the owner. If you have any doubts about the quality of your tap water, the health department is an important point of contact. They will provide you with the contact details of drinking water laboratories in your area and you can send in a water sample. Private laboratories also offer tap water tests. Simple tests with few parameters cost around €40. You can find more information via the links below.

But even tap water has an expiration date. According to the Federal Environment Agency, water that has been standing in a pipe for more than four hours should no longer be used for drinking. Contamination can occur due to prolonged contact with the pipes. Our drinking water is not sterile, but the microorganisms it contains are usually harmless. In larger concentrations, if there has been sufficient time for them to multiply, microorganisms can cause health problems. It is best to let the water run briefly until it is cooler and fresher. The water that has run out can be collected and used, for example, to water flowers.

Problems with excessive lead levels in drinking water caused by old lead pipes are now rare, except in old buildings that have not been renovated. Since December 1, 2013, the limit value for lead has been 0.01 mg/l. This can only be complied with using lead-free installations. If in doubt, contact your landlord or property manager to clarify whether there are still lead water pipes in your house. If so, these should be replaced as soon as possible.

The current guide "Drinking water from the tap" published by the Federal Environment Agency provides many more helpful tips on this topic. Here you will also find the Federal Environment Agency's position on additional purification systems, such as installations for decalcifying water. Use the link below to download the guide.

It is important to drink plenty of fluids, especially on hot summer days. If you would like to use tap water but don't want to carry around a large, heavy water bottle, you can use the refill stations in the Mainz city area.  The concept behind the stations is simple and straightforward. Shops with a refill sticker on their window or door will fill your water bottle with tap water free of charge. The Mainz environmental shop is also a refill station. You can find out where the other stations are located by clicking on the link below.