West Marin Septic Inspections, Repairs & Replacements

Septic is the norm in West Marin

Inverness, Point Reyes Station, Olema, Marshall, Nicasio, and most of the San Geronimo Valley have no public sewer, so homes rely on individual septic systems permitted by Marin County Environmental Health Services. Many were installed decades ago, before current standards, on lots with shallow soils, clay, steep slopes, or groundwater close to the surface. That makes regular pumping, good maintenance, and a careful inspection before buying especially important here.

Point Reyes Station, Inverness & Olema

Inverness homes are spread along steep, wooded slopes above the bay, often on narrow lots with limited room for a leach field and its reserve area. Point Reyes Station and Olema mix village lots with ranch and agricultural properties. Common issues include aging tanks, fields that struggle in wet winters, and older systems serving homes that have grown over the years. Alternative systems, such as mounds, sand filters, and pressure-dosed fields, are common where conventional fields won't fit.

Marshall, Tomales & the Tomales Bay shoreline

Along the east shore of Tomales Bay, homes sit on a narrow strip between the highway and the water, which leaves little room for a conventional field and puts systems close to the bay. Tomales Bay's water quality is closely watched, and septic systems are one of the sources regulators consider, so shoreline repairs and replacements can face tighter setbacks and more review. Inland around Tomales and Dillon Beach, ranch properties often have older systems serving several structures.

Nicasio & the San Geronimo Valley

Nicasio's ranches and rural homes are on septic, as are most homes in Woodacre, San Geronimo, Forest Knolls, and Lagunitas. In the valley, many homes sit on small, shaded lots near Lagunitas Creek and its tributaries, home to one of the region's most important coho salmon runs, which means creek setbacks matter. The county has studied community wastewater options for parts of the valley over the years, but individual septic systems remain the rule.

Bolinas & Stinson Beach

Bolinas is split. The Bolinas Community Public Utility District runs a small sewer system, with roughly 160 connections, but around 420 Bolinas homes are on septic overseen by the county, including much of the Mesa. The county has been investigating surfacing wastewater along the Big Mesa bluffs. Stinson Beach is different again: its roughly 750 septic systems are overseen by Stinson Water, which runs its own inspection program.

Rules to know in West Marin

• Short-term rentals. A Marin STR license application or renewal requires the county's septic inspection form, completed within the past 12 months by an approved professional. See STR and home-sale inspections.
• ADUs and remodels. Building permits trigger a septic review, and major remodels or expansions can require bringing the system up to current code. See ADU and remodel septic reviews.
• The septic program update. Marin is revising the rules that set inspection triggers, permits, and repair and replacement requirements. Expect changes, and confirm current rules with the county before major work.
• Approved professionals. Marin publishes lists of septic contractors and alternative-system service providers it recognizes.

Septic trouble or an inspection deadline in West Marin? Call (707) 867-1221 or request an inspection or estimate from a local septic contractor.