Cal. Health & Safety Code § 25395.70
(a) “Contiguous property owner” means a person who owns a site that is adjacent to or otherwise similarly situated with respect to another site that is, or may be, contaminated by a release or threatened release of a hazardous material and that is not owned by that person, and who demonstrates, by a preponderance of the evidence, all of the following:
(4) The person is not potentially liable, or affiliated with any other person who is potentially liable, for the release at issue through any of the following circumstances: