Osterville septic help: West Bay, the Bumps River and where the new sewer is going

One village, two estuaries

Osterville sits between Marstons Mills and Centerville on the south side of Barnstable, about 3,591 people in ZIP 02655 at the 2020 census and far more in July. The village splits along its drainage. Wianno, Seapuit and the land around East Bay and West Bay drain into the Three Bays system, which the state lists as nitrogen impaired. The east side, along the Bumps River, drains into the Centerville River and East Bay system, which has its own state nitrogen TMDL from 2007. On a septic question, the first thing to know is which of the two watersheds your house sits in, because the town code and the sewer schedule treat them differently.

The flow cap on Three Bays lots

Barnstable Town Code Section 360-45 limits septic design flow inside the Three Bays and Popponesset Bay watersheds to 440 gallons a day per 40,000 square feet of lot. A like for like repair of a failed system is not caught by it, but a new house, an added bedroom or a change of use usually is. On small Osterville lots near the water that often means a nitrogen reducing innovative or alternative system rather than a plain tank and field. The cap does not cover the Bumps River side, where state Title 5 and the Board of Health rules govern alone.

Where sewer pipe is going in Osterville

Osterville is the first south side village outside Hyannis to see new town sewer. The Route 28 West Sewer Expansion, part of Phase 1 of Barnstable’s 30 year wastewater plan, runs pipe on Route 28 from Phinney’s Lane to Route 149, on Osterville West Barnstable Road from Flint Street to Bumps River Road and from there to the Cape Cod Collaborative School, and on Old East Osterville Road, Oldham Road and Marquand Drive. Construction closed about 0.7 miles of Bumps River Road between Osterville West Barnstable Road and Pond Street. A bid listing for the FY25 contract shows $27,689,854; confirm with the town. Osterville Woods and the neighborhoods around it are a separate planned project with mostly gravity sewer, some low pressure pipe and at least one pump station. If your street is on one of those lists, ask the Division before you spend on a full replacement; a sewer connection may be the better money.

Wells, COMM water and setbacks

Most Osterville homes drink public water from the Centerville Osterville Marstons Mills Water District, which pumps from 19 wells across the three villages and keeps its office at 1138 Main Street, Osterville. The district began in 1938 as the Centerville Osterville district and took the COMM name in 1986. A public supply well means a Zone I and a Zone II around it; a septic design close to one of them gets closer review, so a designer will check the district map first. Houses still on a private well need the Title 5 setback from well to leach field on their own lot and on the neighbor’s.

Permits, sales and money

Every repair needs a Disposal Works Construction Permit from the Public Health Division in Hyannis; the town fee schedule revised 20 March 2026 lists $100 for a failed system repair. A Title 5 inspection is due within two years before a sale, and a seller inside a nitrogen sensitive area discloses it under the 2023 state changes. As a Barnstable County village, Osterville can use the Cape Cod AquiFund loan, alongside the state septic credit. Next door, Marstons Mills shares Three Bays and Centerville shares the Bumps River side; the Barnstable page covers the whole town and the service areas page lists every town and village.

Sources: ZIP 02655 count via the zip-codes.com Barnstable County listing (2020 census); Three Bays and Centerville River watersheds via the Cape Cod Commission 208 watershed summaries and the MassDEP Centerville River and East Bay TMDL (EPA approval 18 Dec 2007); Section 360-45 via eCode360 as on our Barnstable page; Route 28 West streets via CapeCod.com and the town engineering RFP; Bumps River Road closure via Patch; FY25 bid figure via a ConstructConnect bid listing; Osterville Woods scope via a ConstructConnect project listing; COMM district wells, office and history via commwater.com, capecodfd.com and the MassDEP SWAP report; fee schedule (rev. 20 Mar 2026) as on our Barnstable page; all read 11 Nov 2026.