Washington State Septic Systems
Washington State Septic Systems: Glacial Till, Volcanoes, and a State Split in Half by Rain Roughly a quarter of Washington households rely on an onsite sewage system (OSS) — the state’s formal term for septic — and few states pack this much environmental variety into one set of rules. West of the Cascades, homeowners deal with dense glacial till and a water table that rarely drops. East of the mountains, the challenge flips entirely: a rain-shadow desert where the problem…