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Starting in July, the Tacoma-Pierce County Health Department will require stress tests of drainfields for property sales inspections of gravity and pump to gravity systems. This document outlines the requirements and policies for repairing or replacing septic tanks, including details with regards to testing procedures, repairs, and replacements of defective tanks. 

Requirements for Repairing Septic Tanks: 

  •  Only two repairs permitted before replacement is required: Tanks can only be repaired twice before requiring replacement. This includes fixing cracks and holes. 
  • Certification and Testing: Only certified septic professionals can perform repairs, and they must conduct a watertightness test post-repair, either over 24 hours for unoccupied systems or 8 hours for occupied homes. 
  • Reporting: Repair details and test results must be reported in the OnlineRME system, documenting the duration of the watertightness test. 

Requirements for Replacing Septic Tanks: 

  • Compliance with Regulations: All replacement tanks must comply with the Environmental Health Code and relevant standards and guidelines. 
  • Initial Inspections: Every tank replacement requires a full operation and maintenance inspection, including a stress test for certain systems to assess the drainfield’s functionality before proceeding. 
  • Installation Requirements: New installations must include outlet filters, and existing systems may require updates like risers or control panels to meet current standards. 
  • Design and Location Consistency: Replacement tanks should match the original in size and location unless approval for changes is granted. This is crucial for maintaining system integrity and ensuring proper functionality. 

Special Cases exist for pump tank and aerobic treatment unit replacements – contact the Tacoma-Pierce County Health Department. 

System Stress Test 

Specific testing procedures must be followed by certified septic professionals. These procedures vary slightly depending on whether the residence is occupied or not. Testing simulates typical water usage.  

Performing the Stress Test: 

  1. Volume: Water is added based on occupancy: 120 gallons per bedroom for unoccupied systems, and 120 gallons per residence for occupied ones. 
  1. Method: Water is introduced directly into the septic or pump tank or via the distribution box using straightforward methods like a 5-gallon bucket or a flowmeter. 
  1. Observation: The test checks if water returns to the tank or distribution box, indicating blockages or leaks. This is typically done 24 hours after the  

If the tank fails the Test: 

  • Further Investigation and Action: Failure prompts further investigation and possibly extensive repairs or replacement of the system. 
  • Documentation: Deviations and failures must be documented by certified professionals. 
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