Zone S1 (Wellhead Protection Zone)

In zone S1, the use of plant protection products is prohibited. 

Zone S2 (Inner Protection Zone)

Special care needs to be exercised when plant protection products are used in Inner Protection Zone

S2. A crucial function of Zone  S2 is to ensure that groundwater approaching a drinking water well is particularly effectively protected. For this reason, the chemicals legislation (available in French/German/Italian), prohibits the use in zone S2 of plant protection products that could enter a drinking water well as a result of their mobility and degradability (specified in the list published by the FOAG). A corresponding requirement is included when a new plant production product is approved if the Federal Office for Agriculture (FOAG) responsible for the approval concludes that the plant production product is not suitable for use in Zone S2. However, the special features of the Inner Protection Zone S2 are not sufficiently taken into account in this assessment in the light of EU Directives. The FOAG publishes a list of plant protection products whose use is prohibited in Zone S2.

The use of plant protection products on railway tracks is generally prohibited in Zone S2.

Of particular relevance in zone S2 are the so-called preferential flow paths along which pollutants can pass rapidly and almost unimpeded into groundwater. To assess whether a plant protection product is suitable for use in Zone S2, these preferential flow paths, together with the short residence time of the groundwater in Zone S2, should therefore also be taken into account.  

A study was commissioned by the FOEN to determine which plant protection products can be tolerated in zone S2 from the perspective of drinking water protection. A summary of the results (in German, with English abstract) was published in the magazine gwa (12/2001).

Zone S3 (Outer Protection Zone)

There are no specific regulations for the use of plant protection products in Zone S3, with the exception of the general prohibition on the use of plant protection products in forests. In addition there is a list of plant protection products whose use is prohibited in Zone S3, which was issued on the basis of earlier assessments during approval of the product:

Area of contribution Z_U and Z_O 

In the areas of contribution the Cantons issue case-specific restrictions depending on the situation for the use of those PPPs that actually pollute the groundwater in that specific case.