It all depends on the last few metres
On the way from the water meter to the tap, drinking water can be contaminated by a variety of substances from the installation materials. The most notorious of these is lead. This heavy metal was used for a long time as a material for water pipes due to its excellent technical material properties. However, lead dissolves in water in concentrations which bear a risk to health and is therefore not suitable as a material for drinking water installations. It should be replaced completely as soon as possible by more appropriate materials. Already since 1 December 2013 a new limit value of 10 µg/l for lead in drinking water is valid. From 12 January 2028 on, this limit value will be further lowered to 5 µg/l. As a consequence, certain lead-containing alloys currently assessed as hygienically suitable for the contact with drinking water will not be accepted anymore. Furthermore, the amended Drinking water ordinance (TrinkwV), which became effective on 24 June 2023, states the prohibition of lead pipes. According to that lead pipes as well as parts have to be removed until 12 January 2026.
Materials in contact with drinking water
In the drinking water installations area, a variety of materials - such as plastics and metals for pipes, sealing materials and valves - are used which might be partially released into the water and, in doing so, would affect its quality. Organic substances in particular can also enhance the growth of bacteria and lead to the microbial contamination of drinking water.
Design and planning of drinking water installations
However, the planning, construction and operation of a drinking water installation are also critical for the quality of the water. Unnecessarily long pipes, “dead” pipe sections (dead ends), little-used pipe sections, poorly insulated pipes and insufficiently high temperatures in water heating all serve to decrease the quality of drinking water. The planning and execution of a drinking water installation have to be carried out by specialised companies.
What users can do to maintain drinking water quality
As a user you too can do a few things to maintain drinking water quality, for instance by flushing standing water (stagnant water), regularly flushing through little-used pipeline sections and alerting the operator (owner, administration) to any instances of maladministration.