The Washington Court of Appeals recently issued a published opinion involving downhill homeowners' claims against neighboring uphill homeowners and a neighboring uphill undeveloped property owner for damage to their residence caused by a clogged private sewer line shared by the homeowners. The Court affirmed the trial court's order directing the neighboring uphill homeowners (who used and benefited from the sewer line) to pay an equal share to repair the sewer line, dismissing the claims against the neighboring uphill homeowners for damage to the residence, and dismissing all claims against the neighboring uphill undeveloped property owner (which did not use or benefit from the sewer line). The Court held that no controlling legal authority imposed an affirmative duty on the parties to inspect the sewer line.
During the course of its opinion, the Court discussed a property owner's potential liability when the roots of trees on the owner's property invade a neighboring property and cause damage. It pointed out that the Washington Supreme Court resolved a 1945 dispute involving such facts by holding that "it is the duty of the one who is the owner of the offending agency to restrain its encroachment upon the property of another." Luckily for the neighboring uphill undeveloped property owner in the recent case, the roots of the tree on its property clogged the portion of the sewer line underneath its property but did not invade any neighboring property.