Drinking water from the tap - intended for drinking or cooking - does not require any other treatment. Water treatment or water softening in the household must never lead to hygienic disadvantages (e.g. bacterial contamination of the system with subsequent bacterial contamination of the water).
In addition to devices for softening, there are also devices on the market that are designed to filter out harmful substances such as heavy metals and chlorinated hydrocarbons. The use of these often very expensive devices is superfluous, as drinking water from the waterworks is of food quality. It is therefore generally unnecessary to boil drinking water from the tap. Drinking water quality can even suffer as a result of post-treatment in the household if the installed appliances are not properly maintained. Even devices that promise certain effects through magnetic fields or electrodes without chemicals have not yet been able to prove their positive effect.

The Drinking Water Ordinance stipulates at what intervals and to what extent the operator of a water supply must carry out quality tests.
In order to prevent the spread of dangerous intestinal diseases, additional microbiological tests are required. For example, no coliform bacteria or Escherichia coli must be detectable.

The public health department checks the water analyses that the operator must submit at specified intervals and regularly inspects the individual parts of the drinking water system.

A wide range of influences from the living and non-living environment can affect the quality of water, meaning that the relevant catchment areas and sources must also be protected and monitored in order to ensure that the population is supplied with safe drinking water. So-called water protection zones are therefore designated by the responsible water authority. In these water protection zones, special rules of conduct and restrictions apply in order to protect the groundwater that is used to produce drinking water from contamination, particularly from behavioral factors.

Water extraction from surface waters, springs and groundwater-supplied wells, drinking water treatment and distribution via the pipe network is ensured by the water supply companies, unless the water is obtained from an in-house water supply system. The quality of the water is monitored from extraction, treatment and distribution via the public pipe network and domestic installations right through to the tap. Regular quality assurance measures include monitoring inspections of the water protection zones and water supply facilities by the public health department and, in particular, tests for physical, chemical and microbiological components of the water in specially qualified independent testing laboratories. The results of these tests are checked by the public health department.

The quality of drinking water can also be impaired after it has left the waterworks. This can be caused by the materials of the pipes used in the public water pipe network and especially in domestic installations. In accordance with scientific findings, requirements have been established for reasons of preventive health protection, which have been reflected in standards and technical regulations, among other things. Compliance with these standards and technical regulations is necessary for drinking water quality, so that only experts and specialists who are registered in the water supply companies' register of plumbers are permitted to carry out work on drinking water supply systems.

In addition to public water supplies, private water suppliers are also subject to monitoring by the public health department. Here too, the parameters of the Drinking Water Ordinance must be adhered to and the structural condition must comply with the general rules of technology.

These can be found, for example, in schools, daycare centers, hospitals and retirement and nursing homes.

In addition to regular inspections of the public water supply and private water supply systems, the public health department carries out random checks of domestic installations from which water is supplied to the public as part of annual screening programs.

The public health department monitors the quality of drinking water and observes the influences on groundwater and drinking water quality from the environment and advises on all matters relating to drinking water hygiene:

• Drinking water quality (for example brown water, ingredients, quality, hardness),
• private domestic installations,
• public domestic installations
• Advice for homeowners, wells and individual water supplies,
• Investigating complaints in this regard, including at public events
  (non-stationary supply systems) and
• Advice on non-drinking water systems (rainwater utilization systems)