There can be four major costs in converting from a septic system to sewer service: the public sewer infrastructure, side sewer construction, septic system abandonment and connection fees. The estimates shown are approximate costs for connection in 2020, and should be adjusted accordingly for later years.
Sewer pipe in street: $4,000 - $25,000+
This cost depends on whether a public sewer is adjacent to your property and suitable for your use. A public sewer is usually eight inches or more in diameter and may be located in a street or a sewer easement through private property. If public sewer is available, you may owe a reimbursement (called a latecomer’s charge) to the installer of public sewer facilities such as pump stations and pipes serving your property.
If no public sewer is available, you would be responsible for extending the public sewer from the end of the City’s existing system to and along the frontage of your property prior to making a connection. The cost to extend a sewer pipe varies, depending on the length of the project, difficulty of the terrain, soil type, need to acquire easements, the amount of engineering work required, pipe and backfill materials specified, methods of construction employed, and surface restoration requirements. In rare cases, you may also owe a latecomer’s charge as described above. Construction of a public sewer requires permitting and inspection by the City’s Community Planning and Development Department at 360.753.8314. To receive a permit, you would be required to submit design plans, conforming with the City’s Engineering Design and Development Standards, for review and approval.
The cost of a sewer extension project can sometimes be shared with your neighbors who also would benefit from the availability of a sewer adjacent to their properties. Longer, shared sewer projects allow for an economy of scale in design and construction that reduces the cost per property, as compared to each property owner sequentially installing a separate, smaller sewer extension project. The City will be constructing a limited number of neighborhood sewers in priority areas. See the Neighborhood Sewer Extension flyer for more information.
Side sewer construction: $4,000 - $14,000
A side sewer is a four– to six-inch diameter pipeline that runs from your house to the public sewer. The property owner is responsible for construction of the side sewer. A design that allows wastewater to flow via gravity from your house to the sewer is preferred. However, the City may allow the installation of an individual privately owned residential grinder pump if elevations don’t permit a gravity flow system. A portion of this sewer (known as a sewer lateral) may have been stubbed out from the public sewer to your property when the sewer main was constructed. Property owners may do work on their own property, but construction within the public right-of-way or City easements requires hiring a licensed contractor registered with the City.
The existing pipeline from the house to the septic tank may be used as part of the new side sewer only if it is a minimum of four inches in diameter. A side sewer is then constructed the rest of the way (sometimes wrapping around the house) to the public sewer. Alternatively, plumbing beneath the house sometimes can be redirected toward the public sewer so as to avoid having to construct a pipeline around the house. The cost is highly variable depending on the side sewer length, terrain, surface conditions, as well as the need for a pump. These costs are paid directly by the property owners to the contractor they hire at the time the work is done.
Septic tank abandonment: $1,200
The Thurston County Environmental Health Program (TCEH) requires that septic tanks be properly abandoned when no longer needed. The existing side sewer as well as the installation of the new side sewer must be completed, inspected and accepted before the existing septic tank is removed from service and abandoned. The abandonment process involves obtaining a permit from TCEH; having the tank pumped out one last time; removing and disposing of the lid or crushing the lid and using it to fill the tank; and filling the empty septic tank with compacted earth, gravel or sand. Specific requirements for septic tank abandonment can be obtained from TCEH at www.co.thurston.wa.us/health/ehoss/.
Connection fees: $2,100 - $12,000
The City collects a number of fees for permits, inspections and providing collection system and treatment plant capacity. These fees are due prior to connection to a public sewer.
- LOTT Capacity Development Charge1: $1,512 - $6,231
- City Wastewater GFC2: $0 or $3,442
- Permits for Sewer Connection: $283 - $2,000+
- Septic Abandonment Permit: $275
1 The property may be eligible for a 50% to 75% rebate on the LOTT Capacity Development Charge. Contact City staff for more information.
2The City Wastewater GFC is waived per OMC 13.08.205(C) for properties with an existing septic system that connect to the sewer system within two years following notice of sewer availability or connect within two years of purchasing the property, and for properties that qualify for a LOTT CDC rebate.