In Switzerland over 80% of drinking water comes from groundwater sources. The rest is supplied from lake water.

Groundwater is generally of good quality in Switzerland. In the main it can be used for drinking water supplies without any restrictions.

However, measurements show that undesirable substances are often present in groundwater. They include nitrates, pesticides, halogenated hydrocarbons etc. Pesticides have been found in the groundwater at 50% of the measuring points sampled, usually in very low concentrations. Groundwater protection therefore continues to be a priority so that future generations can also benefit from this resource.

The National Groundwater Monitoring programme NAQUA provides a nationwide survey of the status of groundwater (quantity and quality). The data forms the basis for evaluation of the impact of the groundwater protection measures taken and for further measures to be taken promptly if required. It is also used to inform the public of the status of groundwater in Switzerland.

Many cantons have additional measuring points and can give detailed information on the groundwater in their regions.

The federal government defines the legal framework for water protection.

The cantons are responsible for implementation of groundwater protection at cantonal and municipal level. They designate protection zones and monitor them, issue approvals under water protection legislation for construction activities, use of liquids capable of polluting water etc. To guarantee compliance with the specification, the cantons have set up their own agencies.

The federal government is responsible for collecting nationally relevant environmental data. It operates the National Groundwater Monitoring programme NAQUA to determine the quantity and quality of groundwater in Switzerland and take any measures necessary.

The cantons are responsible for collecting environmental data at regional and cantonal level. They manage their own networks to monitor the groundwater in their regions. If a canton discovers contamination, it must determine its extent and causes, assess the effectiveness of any measures to be adopted and ensure that they are actually taken.

Large water providers operate their own measuring points above the catchments to monitor the groundwater and initiate measures at an early stage if problems occur.

Just like surface water, groundwater is in public ownership.

The federal government looks after household use and protection of water resources as part of its responsibilities.

The cantons take care of the water resources.

They are responsible for the actual use of groundwater and sparing treatment of the resource so that water supplies remain guaranteed for future generations.  For instance, the cantons can issue concessions for groundwater use and levy the relevant charges.

Around 400 litres of new groundwater is formed on average per m² of land area in Switzerland every year. The average cost of drinking water in Switzerland is CHF 1.70 per m³ (1000 l) of water. Therefore each hectare of land (10,000 m²) generates groundwater with a market value of some CHF 6800 every year.

Water hardness indicates the lime content of the water.