Checking Contaminated Sites & Polluted Land Before You Buy
An entry in the register of polluted sites does not automatically mean danger — but it deserves a check. This page explains what separates a “polluted” site from one “needing remediation”, where to find a parcel's entry, and what it means for a purchase. Factual, not alarmist.
This page explains publicly accessible registers and does not constitute tax, legal, construction, or financial advice. Consult a qualified professional for legal or tax questions.
An entry does not decide livability, but it does shape possible duties and costs when you rebuild or change use. Knowing it before you buy lets you plan calmly instead of being surprised later.
A polluted site is a place whose soil is polluted by waste — for example a former landfill, a former industrial site, or an accident location. “Polluted” does not automatically mean “dangerous”: the register of polluted sites expressly distinguishes a polluted site from one needing remediation.
Source: Register of polluted sites (FOEN) · Glossary: contaminated sites
Each canton keeps the register of polluted sites. The entries are publicly viewable through the map portal geo.admin.ch and the cantonal GIS portals; as a PLR theme they also appear in the PLR cadastre of an affected parcel.
Source: Federal geodata (geo.admin.ch)
The register classifies sites by need for action: no action needed, monitoring needed, or remediation needed. Only the last category counts legally as a contaminated site. For most polluted sites no measures are needed as long as the use does not change.
An entry is no cause for panic, but a cause for clarification: whoever changes the use of or builds on a polluted parcel may have to investigate and bear the costs. Before buying, clarify with the cantonal contaminated-sites office which classification applies and whether your project triggers measures.
Every fact in an alpflo report carries exactly one of these states — so you can see at a glance what's documented and what isn't.
Confirmed in an official Swiss register. Direct source.
Register queried; nothing on this parcel. The absence is documented.
Derived from a model or an API: real, but not directly from the register. Please verify.
Hit an edge case. Stated honestly at the boundary, never silently discarded.
Is a polluted site the same as a contaminated site?
No. “Polluted” describes soil containing waste; a “contaminated site” is a polluted site that demonstrably causes harmful effects and therefore needs remediation. Most polluted sites are not contaminated sites.
Where do I find out whether a parcel is polluted?
In the cantonal register of polluted sites, publicly viewable through geo.admin.ch and the cantonal GIS portals. As a PLR theme, the entry also appears in the parcel's PLR extract.
Do I have to remediate a polluted site?
Not necessarily. A duty to remediate exists only if the site is classified as needing remediation. With unchanged use, no measures are required for many entries — a rebuild or change of use can, however, change that.
Who bears the investigation costs?
That follows the polluter-pays principle and cantonal practice. Clarify the cost question before buying with the cantonal contaminated-sites office — an entry can trigger investigation or remediation costs.
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