Onsite Sewage Systems
Older and poorly maintained on-site sewage systems can leak sewage that enters Puget Sound.
Indicator Lead: Jeremy Simmons, Washington State Department of Health
Data last updated on June 28, 2017

Indicator and target description

What is the indicator?

This indicator is onsite sewage inventory, inspection, and repair.

This indicator tracks and advances the proper use and care of onsite sewage systems (septic systems) in sensitive and high-risk areas of Puget Sound, in order to protect public health and water quality. The indicator consists in three distinct measures: inventory, inspection and repair of onsite sewage systems in designated areas. The designated areas include Marine Recovery Areas and other areas with comparable requirements. State rules require all homeowners to regularly inspect and maintain their onsite sewage systems. However, in Marine Recovery Areas and other designated areas, local health jurisdictions engage more directly with homeowners to help ensure systems are inspected and maintained to reduce public health risks.

The 12 Puget Sound local health jurisdictions (LHJs) report data semi-annually to the Washington State Department of Health (DOH). Data for the 2020 target were compiled starting in 2011 and four reporting cycles have now been completed.

All 12 Puget Sound local health jurisdictions have adopted comprehensive management plans for onsite sewage systems under the state onsite sewage rule. The management plans frame the local Operation & Maintenance programs. While the 12 local Operations & Maintenance programs have common elements, they are all uniquely designed and implemented. The Department of Health oversees the statewide onsite sewage rule and collects and interprets local data for the Puget Sound targets.

What are the targets?
2020 targets
  1. 1. Inventory all onsite sewage systems in Marine Recovery Areas and other specially designated areas; be current with inspections at 95%; and fix all failures.
  2. Phase in an expansion of Marine Recovery Areas and other specially designated areas to cover 90% of Puget Sound's unsewered marine shorelines.
Interim targets

Link to interim targets (PDF)

Progress summary and data

Is the indicator making progress toward the 2020 target?

The results for this indicator are mixed.

The 2014 interim target for inventories was met, but the interim target for inspection rates fell short.

  • Collectively, local health jurisdictions have inventoried more than 65,000 septic systems. Of these, 95 percent are fully documented, generally meaning that the county has a record of the system in their database, including its condition and inspection status.
  • Local health jurisdictions have made advances in inventorying and inspecting septic systems since 2011. Most recently, more than 27,000 systems were up-to-date with inspections, or 42 percent of the inventory.
  • Progress on fixing failed septic systems is not yet available. This indicator is still being developed.
Did this indicator meet its 2016 interim targets?
Inventories of systems in designated areas are 85 percent complete.
Yes Inventories are 95 percent complete. 
Onsite septic systems inspection levels at 75 percent in designated areas.
The target is not met but there was progress. Inspection rate was 42 percent at the start of 2015.
85 percent of identified failures in designated areas are repaired or mitigated 
No data Data tailored to the target are not yet available.

Latest Data




Source: Washington State Department of Health, Office of Environmental Health and Safety

Progress toward the 2020 target to inventory, inspect and repair onsite sewage systems in designated areas is mixed. There have been advances in inventorying and inspecting septic systems. However, the analysis of progress on fixing failures of septic systems is pending due to lack of data.

The 12 Puget Sound local health jurisdictions (LHJs) have inventoried nearly 67,000 onsite sewage systems in Marine Recovery Areas and other specially designated areas since 2011. The inventory includes septic systems with official records and that are current with inspection, systems that are overdue for an inspection, and systems that are suspected to exist but are not officially documented. Since 2011, the baseline reference year, nearly 14,000 additional septic systems were added to the inventory. The overall percentage of onsite sewage systems that have been inventoried and documented rose from 86 percent to 95 percent during this period and reflects progress toward the 2020 target of 100 percent.

The percent of septic systems that have been inspected and the inspection is current increased from 33 percent to 41 percent between 2011 and 2016. Although there has been progress relative to the baseline reference, the indicator is still far from reaching the 2020 target value of 95 percent. Working with homeowners to ensure and track ongoing regular inspections is challenging and costly. State and federal funds have provided additional resources for work on the 2020 targets.

The third measure of this target is to fix all failures in the designated areas. The analysis is pending due to lack of data tailored to the target. The Washington State Department of Health (DOH) is working with the LHJs to standardize an approach to track and report system repairs.

Why is it happening?

The local health jurisdictions are currently working to adapt and align their programs to fit with these ambitious regional targets.

The Puget Sound Operations & Maintenance (O&M) programs in local health jurisdictions are inherently complex and costly to implement. They all work from the same rule requirements and core elements, but are all tailored to local conditions, budgets, and ways of doing business. They require significant planning, infrastructure, personnel, public education, political support, community buy-in, financial resources, and smart execution.

At all levels of government, funding for decentralized wastewater programs and infrastructure dramatically lags behind public investment in centralized sewer systems. State financial support for the Puget Sound O&M programs has never materialized at a scale originally envisioned when the state onsite sewage and Marine Recovery Area laws were enacted. Most O&M program costs are covered locally and are complemented by state and federal grants. The Washington State Department of Health (DOH) surveyed the local programs in 2014 to determine financial need. The analysis documented highly variable local expenditures ($6+ million including grants) and needs, and estimated total annual need at more than $14 million to implement current programs, and more than $24 million to carry out baseline services regionally.

The targets provide a small window into the workings of the local O&M programs. These programs include such diverse activities as financial lending for system repairs, code enforcement, homeowner inspection training, data management, certification of O&M professionals, homeowner notification and reporting, and community outreach.

Management—characterized here as O&M—has long been recognized as the weak link in the widespread use of onsite sewages systems when compared to centralized sewers. The picture is gradually changing in the Puget Sound region as local O&M programs take root, but it will continue to take significant investments and smart thinking to effectively design and deliver these utility-style programs and services on an ever-expanding scale.

Homeowners and elected officials alike are increasingly seeing the need for and benefits of these programs. The Action Agenda and regional targets will continue to shape and guide these efforts.

Target 2: Program extension to unsewered shoreline.

There has been no progress toward the target of expanding Marine Recovery Areas and sensitive area designations to 90 percent of Puget Sound's unsewered shoreline. The Department of Health estimates that the existing designated areas cover approximately 450 miles of unsewered Puget Sound shorelines. This represents about 20 percent of Puget Sound’s unsewered shorelines, only a fraction of the target for 2020 (90 percent).

The law can only be applied in areas with documented water quality impacts associated with existing onsite septics, and there may be additional legal and administrative issues limiting the expansion of MRAs to meet this target.

DOH and LHJs have asked the Partnership to revisit and reconsider this part of the target due to concerns with its feasibility