Sewer Requirements

If there will be a plumbing fixture(s) in the basement, which is liable to back-up from a sewer line, a backwater valve is required. Regulations and guidelines for the installation of backwater valves for homes and businesses in low-lying areas of Boston can be found in the BWSC Regulations.

Backwater Valve Brochure

B-14 Backwater Valve Standard Detail

The plumbing of each building must have a separate independent sewer connection(s) to BWSC sanitary/combined sewer system outside of the building.

When there is a separate sanitary sewer in the street, the site's sewer lateral must be connected to the sanitary sewer. When there is a combined sewer in the street, the site's sewer infrastructure must leave the property in a separate pipe from the storm drain system and then connect to the combined sewer via a wye connection once in the public right of way. No connections to manholes are allowed.

Detail of the connection, if it is not being made to an existing wye branch on the sewer, must be shown on the plans. Connection to clay, PVC, concrete, iron, or brick pipes will be made using an approved coring bit and mechanical device.

B-12 Connection Standard Detail

Minimum pitch is 1/4 inch per foot for building sewer connections. Building connections shall be bedded in 3/4 inch minimum crushed stone to at least half the pipe diameter.

When sewer connections are being made to existing wye branches, the distance from a manhole must correspond to the distances shown on BWSC record plan. All existing wyes accessible from the site must be shown, to allow for field changes. New wye branches must connect to the main and not the sewer manholes.

Provide a clean out on the portion of the building sewer on the owner's property at the property line when there is a building set back from the property line.

All chimney connections shall be encased in concrete.

B-15 Chimney Connection Standard Detail

Grease traps or interceptors shall be required on sewer lines for all restaurants and commercial food handling establishments.  BWSC may require grease interceptors for any fixture or drain which introduces large amounts of animal or vegetable fat, oil or grease. All submissions shall be sent to Enforcement for review and approval.

Commercial Kitchen Grease Traps

Gas Oil Separators are required for indoor parking garages for six or more vehicles and indoor parking garages that will be used for automotive purposes other than just storage (i.e., washing, maintenance, etc.), and gas stations. Sewer separators must discharge to the sewer/combined system.

G-01 Gas Oil Separators Standard Detail

The sanitary sewer connections shall be laid at least 10 feet apart from any new or existing water services connections.

All abandonment of the existing building sanitary sewer services must be cut and capped off at the main(s) in the street. All such work must be performed by a Licensed Contractor.

All new sewer connections and manholes must be stationed. When possible, STA 0+00 should be aligned with the corner of the property lines of the building being constructed.

BWSC has the right to inspect building sanitary sewers, building storm drains, and other private sewers, grease traps, oil-particle separators, and other appurtenances tributary to the BWSC's wastewater and storm drainage systems. Inspection points must be delineated on the site plan, along with sign off by a BWSC inspector.

In any existing building, vacant for over one year, to be renovated or substantially rehabilitated, it is required that if the sewer lateral is going to be reused, it must be televised. BWSC will determine if the existing lateral can be reused after review of the video provided by the proponent. A new roof drain must be provided if there is no existing drain in the building.

For all new construction of buildings, the engineer must address the issue of the foundation drain and under drain.

Proposed catch basins and area drains require a "Do Not Dump" plaque that will be purchased from BWSC at the time of the General Service Application.