A water district, with regulatory approvals and permits from the California Department of Health Services, added chemicals — “secondary disinfectants” — to the tap water system to make the water safe to drink. The water complied with all federal and California drinking standards.
Sounds good. No one wants undrinkable drinking water. Problem was these additives caused copper pipes in private homes to corrode.
The owners brought class actions under both nuisance (tort) and inverse condemnation theories. The Superior Court concluded the claims were preempted by both federal and state law.
In Williams v. Moulton Niguel Water District, No. G053002 (May 3, 2018), the California Court of Appeal affirmed, although for different reasons.
The nuisance claim was out because the District is immune from nuisance liability. Under California Civil Code section 3482, “[n]othing which is done or maintained under the express authority of a statue can be deemed a nuisance.” The



