Septic to Sewer

Septic tank

Switching from a septic system to City sewer

Septic systems have limited life spans and frequently fail, impacting the environment and the community's water quality. The City offers a variety of incentives to encourage and assist property owners who may be interested in converting from an existing septic system to public sewer.

View the Neighborhood Sewer Extension List to see if sewer is coming to your neighborhood soon.

Frequently asked questions

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

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.

The following loan is currently available, follow the link for details:

Connection is generally voluntary. However, if your septic system fails or if you plan to expand your home beyond the septic system capacity, the City will require you to connect to the sewer if your property is within 200 feet of an available sewer. See the OSS Permitting Flowchart for more information. The City does not plan to make the conversion of properly functioning septic systems to the public sewer system mandatory. That may change if recovery plans developed by the State of Washington identify the conversion of septic systems as a required action to clean up impaired water bodies within the City of Olympia.

  • It may be required. If your septic system fails or if you plan to expand your home beyond the septic system capacity, the City will require you to connect to the sewer if your property is within 200 feet of an available sewer.
  • Environmental considerations. Even well-maintained septic systems put more stress on the environment, especially in urban areas. Failing septic systems pose a risk to surface water, groundwater and public health.
  • Expansion options. A septic system may limit the ability to expand your house or build (or garden) over portions of your property.

Once connected to the public sewer system, a property owner is required to pay a monthly sewer utility bill. This bill covers the operation and maintenance costs for collection, treatment, and disposal of wastewater, and renovation of the sewers and wastewater treatment facilities. The 2020 sewer rate is $54.32 - $62.52 per month. Sewer rates are set by City Council and the LOTT Cleanwater Alliance annually. State law requires customers to be notified in advance of future increases and allowed an opportunity to be heard and protest.

More than 800 properties currently served by septic systems are adjacent to and eligible to connect to a public sewer. You can reference this Sewer Lookup Map to see if sewer service may be available in your neighborhood.

To determine the actual availability, restrictions, and requirements for connection to the sewer contact Wastewater Utility staff at 360.753.8562 or

When an existing public sewer is available, or a new sewer extension has been constructed, follow the steps in the appropriate guide below to connect to the public sewer.

If you are not sure which type of service applies to you, please contact Wastewater Utility staff at 360.753.8562 or

  • Waiver of the City Wastewater General Facilities Charge (GFC): This incentive is intended to motivate the owners of properties where the sewer is currently available as well as properties benefiting from sewer extension projects. The City’s GFC ($3,442 in 2020) will be waived for properties that abandon a septic system and connect to public sewer within a 2-year time period following formal notification of sewer availability. The City will notify property owners by mail when the sewer becomes available. If you know that the sewer is currently available to your property, there is no need to wait for notice from the City to benefit from the GFC waiver. The GFC will also be waived if you have owned your property less than two years. However, new property owners will NOT be notified of the waiver by the City. Finally, if the property qualifies for a LOTT capacity development charge rebate (see below), it will also be granted a GFC waiver.
  • Rebate for the LOTT Capacity Development Charge (CDC): This incentive is offered as part of the Septic Conversion Incentive Program from the LOTT Cleanwater Alliance. In 2020, the CDC is $6,231. The typical rebate amount is 50% ($3,116 in 2020) with an additional 25% ($1,558) available to property owners who meet the criteria for hardship status. Funding is limited and is available on a first-come, first-served basis. Contact Wastewater Staff at 360.753.8562 to obtain application materials.
  • Neighborhood Sewer Extension Program: The City has funding available to construct a limited number of neighborhood sewer extension projects. Property owners who choose to connect with a new sewer project will be required to reimburse the City a portion of the cost of constructing the sewer infrastructure. The City will pay the rest of the cost. View the Neighborhood Sewer Extension List to see if a sewer is coming to your neighborhood soon.

The City has funding available to construct a limited number of neighborhood sewer extension projects. Property owners who choose to connect with a new sewer project will be required to reimburse the City a portion of the cost of constructing the sewer infrastructure.

See the Neighborhood Sewer Extension Flyer for more information and view the Neighborhood Sewer Extension List to see if sewer is coming to your neighborhood in the next few years.

Most public sewer mains can be designed and completed within a year. If significant street repaving is involved, that work may be delayed until the weather is warm enough to allow the paving materials to be installed properly.

In urgent situations (e.g. septic failure), a public sewer can be designed and constructed in less than three months.

A property’s side sewer should connect to the sewer main in the street on which the property fronts. To facilitate the orderly extension of sewer mains, a side sewer may not extend across an adjacent property to connect to a sewer main. There are some extraordinary circumstances, particularly where sewer mains are located within easements and not the right-of-way, in which side sewers may be permitted to be installed within easements across adjacent properties.

Maintenance is key to preventing the failure of your septic system. If your system has been properly designed, sited, and installed, the rest is up to you. Pump regularly, avoid excess water use, and watch what you put down the drain and flush down the toilet. For more operations and maintenance tips, visit the Thurston County Environmental Health Program's website at

Signs of a failing septic system may include slow draining toilets and drains, an odor of sewage, and wet areas on or near the drain field.


Contact Wastewater Utility staff at 360.753.8562 or

Note: The Thurston County Environmental Health Program (TCEH) is the agency responsible for permitting septic systems throughout Thurston County including within Olympia’s city limits. For information about maintenance, expansion, enhancement, replacement or abandonment of septic systems call 360.867.2673 or visit