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This list highlights the most significant revisions to Chapter 8 On-site Wastewater Treatment System (OWTS) Regulations.
  • Regulations Effective Date: July 11, 2026
Summary of Major Changes
Section 8.4
  • Change of Use Review
    • Previously: Policy
    • Updated: Required when proposing a change or expansion of OWTS use (e.g., bedroom addition, commercial use change).
      • System verification required.
      • System must be functioning as intended.
      • Soil testing may be required unless a compliant test is on file.
      • Engineer letter required for engineered systems, evaluating design parameters under current regulations.
  • Residual Head Test (Squirt Height)
    • Previously: Policy under Operation and Maintenance
    • Updated: Testing required for all zones and must be documented in the engineer’s certification letter.
  • OWTS Certified Inspection Review
    • Previously: Required at property sale
    • Updated: Property sale inspection requirement removed.
      • EPCPH retains certified inspection standards, now offered as voluntary.
      • Issued document renamed Notice of Determination.
      • Certified inspections still required for:
        • Change of Use requests
        • Cesspool remediation requests
        • At the discretion of EPCPH for other reasons as necessary
  • Licensing of System Contractors
    • Previously: required and fee for renewal
    • Update: Introduction of renewal fee waiver (details forthcoming by email to licensed installers).
  • Licensing of System Cleaners
    • Previously: Required all trucks to be inspected
    • Update: Individual truck inspections removed.
      • Companies now licensed through certification course submission.
        • Active companies must submit NAWT (or EPCPH‑approved equivalent) certification.
        • Individual employees are not required to hold certifications.
      • Renewal fee waiver introduced; additional information will be emailed.
  • Certification of System Designers
    • Previously: Not included
    • Update: New corrective education requirements apply when:
      • Soil reports require revision or EPCPH staff must meet onsite to resolve deficiencies.
      • Designs require resubmission or revision (applies to PEs and other professionals).
      • Evaluations will occur annually each December and cover the entire year.
  • Certification of Operation & Maintenance Specialists / System Inspectors
    • Previously: required and fee for renewal
    • Update: Renewal fee waiver implemented (additional details forthcoming).
  • Variance Procedure
  • Previously: Included
  • Update:
    • Variance prohibition added for non-functioning cesspools.
    • Clarification on BOH review for “No Closer Than” variances when documented records exist.
Section 8.5 Soils
  • Updates include rupture resistance, cemented soil classifications, and open profile pit requirements for certain zip codes.
  • Implementation Note:
    • Existing soil reports lacking updated details will be accepted through December 2026 although it is encouraged to updated soils reports where able prior to submission.
    • Beginning January 1, 2027, reports must include cementation information; otherwise, revisions will be required.
Section 8.6 Wastewater Flow & Strength
  • Increased design flow (additional 50 gpd) triggered when occupancy exceeds two persons per bedroom.
  • Clarifications for ADUs and accessory living quarters.
  • Addition of TL3ND treatment level to Table 6‑3.
Section 8.7 Minimum Distances
  • Property line setback reduction allowed from 10 feet to as little as 3 feet without BOH variance, when justified and compliant.
  • Additional clarifications added to Tables 7‑1 and 7‑2.
Section 8.8 – Design Criteria: General
  • Changes include:
    • Clarification that hardening spray foams are not acceptable sealants for OWTS components.
    • Secondary safety features are now required in tank risers.
      • Implementation: All tanks installed under permits—repair, modification, new, or alteration—must comply.
        • Permits already issued, and permits issued for applications received prior to July 10, 2026, at 11:59PM, are exempt but encouraged to begin this installation practice immediately.
    • Floodplains and Floodways:
      • Clarifications of specific floodplains and floodways incorporated directly into the regulations.
      • All installations in floodplains or floodways must comply with the EPCPH Installation in Floodplain/Floodway Guidelines.
Section 8.9 – Design Criteria: Components
  • Changes include:
    • All tanks must be a minimum of ¾ bedded prior to installation inspection.
    • Cleanout requirements:
      • When a cleanout is not already installed outside the structure, a two‑way cleanout must be installed as close to the house as practical, but no more than 50 feet from the outside wall.
      • Implementation: This applies to all installations—repair, modification, new, or alteration for all existing permits as well as those to be issued.
    • Schedule 40 Pipe Required
      • Beginning 5’ prior to the tank and all pipe beyond the tank
      • When variance to setbacks are approved
Section 8.10 – Design Criteria: Soil Treatment Areas (STA)
  • Changes:
    • Several new soil types (FBR, DBR, R‑3) introduced and require professional engineer design.
    • Soil types 4A and 5 require pressure distribution systems with a minimum of two alternating zones.
    • Sand filters are not required for some Type R soils when using TL3ND treatment prior to dispersal.
    • Timed dosing is no longer required in R‑2 soils.
    • Introduction of fractured and deteriorated bedrock guidance for determining LTAR.
    • High rock content soils must now include excavation difficulty in addition to percentage of rock content.
    • Table 10‑3 includes updated sizing adjustment factors, separated for soil types 4A and 5.
    • STA installation beneath paved surfaces is now allowed with:
      • Minimum TL2 treatment,
      • Load‑bearing accommodations,
      • Applicable Table 10‑3 sizing adjustments.
    • Gravity flow pipe must be connected as close to center as possible on the distribution header while remaining offset from lateral lines.
      • Preference remains for use of a distribution box.
      • Implementation of this will be expected on all installations moving forward.
    • Pressure distribution design parameters are consolidated into a single section—no major functional changes.
    • Serial distribution designs are prohibited.
    • When the total STA area (excluding endcaps) is 90% or more covered by chambers, the excavation equivalent may be used as the approved square footage.
    • Fill material requirements:
      • When existing fill is present, all fill extending at least 12 inches below native grade must be removed.
      • Imported sand media must then be placed.
    • Remediation technologies require an EPCPH permit and:
      • OWTS Certified Inspections must be submitted every 3 months for one year, unless otherwise specified.
Section 8.11 – Higher Level Treatment Systems
  • Changes include:
    • Media gradations must be dated within 4 months prior to installation and provided on official letterhead from the source gravel pit or independent laboratory.
    • For adjacent sand filters, the bases must be at least 6 feet apart (sidewall to sidewall).
    • Mound systems:
      • Now divided into three distinct categories:
        • All imported material above grade
        • Sand media entirely above grade but base below grade
        • Top installed both above and below grade
      • Numerous design considerations added, including:
        • Appropriate LTAR selection based on sand elevation and wastewater strength
        • Consideration of linear loading rate based on effluent movement and site conditions
        • Requirements specific to wastewater strength received by the mound
Section 8.12–8.14 Other Systems, Technology Review, O&M
  • NDDS systems now require O&M oversight.
  • Sampling guideline references added.
  • Technology approval process streamlined since this is deferred to CDPHE.
Sections 8.15 & 8.16
  • No changes.
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