Last month, the Washington State Board of Health approved changes to the statewide OSS (On-site Sewage System, or septic system) codes. Here's a summary of the changes:

• Property transfer inspections: Starting in 2027, all OSS must be inspected when the property is sold. The Local Health Officer (for King County, that's Jeff Duchin, and our On-site Sewage System program represents him) may waive this requirement if there's been a recent inspection, and may verify the results of the inspection, require additional inspections, or require repairs on a set timeline. 
• Minor repairs: There's a new definition for "Minor Repair" to clarify that permits aren't needed for some repairs. 
• Repair: The Local Health Officer (in this case, our OSS Program) must:
  • Allow the least expensive repair or replacement of an OSS that meets the rule's requirements.
  • Evaluate all unpermitted sewage discharges and require any that pose a public health threat to be brought into compliance with the rule in a set timeframe.
  • Report OSS failures to the Washington State Department of Health if they are within 200 feet of shellfish growing areas.
  • Not impose more stringent repair requirements on private entities than public entities.
• Remediation: The Local Health Officer (our OSS Program) may develop a policy to allow OSS remediation practices to correct certain problems and failures. This policy can't include remediation practices that damage the OSS or result in insufficient soil treatments. 
• Minimum lot sizes: Minimum lot sizes have been increased by 500 to 1,000 square feet, depending on soil type. 
• Minimum usable land area: New lots that are on OSS must have a certain land area that's usable for OSS installation and repairs. This land can't be under water, paved, impacted by an easement, or otherwise unusable for the OSS. 
• Field verification of proprietary treatment products: OSS manufacturers who use proprietary disinfection and nitrogen-treating treatment components have to verify their products work in the field. This involves collecting samples for 25 installations in Washington to evaluate their performance in the field. 
• Product supply chain: Propriety products can be retrofitted with components that they weren't tested with, if there is a supply chain or other manufacturing disruption. The manufacturer has to provide a statement from an engineer that the retrofit will not impact OSS performance or maintenance. 
• Resilience:
  • Sea level rise: Local Health Officers (our OSS Program) in Puget Sound counties have to identify areas where sea level rise may impact horizontal setbacks to OSS that result in an increased risk to public health.
  • Phosphorus: Local Health Officers (our OSS Program) in Puget Sound counties must identify areas where phosphorus has been found to be a contaminant of concern. They have to identify measures to protect public health and water quality from phosphorus from new and repaired OSS in these areas. In areas where nitrogen is a concern, this is already required. 
  • Nitrogen-based minimum lot sizes for small lots: Lots can be smaller than the minimum requirement if certain safety measures are met and nitrogen treatment is installed on the OSS.