Murray

In January 1986, plaintiffs Leonard and Mary Murray discovered a water leak in their home caused by a break in a one-half inch conventional L grade copper pipe carrying hot water from the hot water heater in their garage to a bathroom in the house. The pipe was about 23 inches below the concrete slab floor. As a result of the leak, the ground underneath the pipe settled, causing a crack in the slab perpendicular to the pipe.

Experts agreed that the leak was caused by a process known as electrolysis, precipitated when the pipe was exposed to a combination of moisture and acidic soil. (See generally Walnut Creek Elec. v. Reynolds Constr. Co. (1968) 263 Cal.App.2d 511, 514 [ 69 Cal.Rptr. 667 ].) One of the experts described electrolysis as involving “a chemical reaction of dissimilar metals in the presence of an acid solution. The transfer of electrons from one metal to another relieves that one metal of a portion of its thickness and structural integrity as evidenced by accelerated corrosion.” The process resulted first in a pinhole and later in a serious rupture of the pipe.

The Murrays presented a claim for damages to defendant State Farm Fire and Casualty Company with…