1. (1) Effluent Sewer Pipe and Header Pipe: The effluent sewer and header must be constructed with materials that conform to state building sewer standards. The effluent sewer and header pipe must have a diameter of at least 3 inches. When the septic tank is fitted with an effluent filter, the nominal diameter of effluent sewer piping may be reduced to at least 1-1/4 inches.
2. (2) Underdrain pipe. Underdrain pipe and fittings must meet or exceed Schedule 40. The underdrain pipe must be perforated in accordance with subsection (4)(d) of this rule or with 1/4-inch slots cut halfway through the pipe at 4 inches center to center.
3. (3) Pressure transport pipe, pressure manifolds, and pressure lateral pipe and fittings must meet or exceed Schedule 40 and be pressure rated. High density polyethylene (HDPE) pipe must be pressure rated under the standards referenced in Chapter 17 of the Oregon Plumbing Specialty Code. Any transitional fittings between material must be manufactured for that purpose.

4. (4) Distribution Pipe and Fittings.

   1. (a) Polyethylene distribution pipe in 10 foot lengths or greater must meet the current ASTM Specification F 667. Pipe and fittings must also pass a deflection test withstanding 350 pounds per foot without cracking or collapsing using the method in ASTM 2412. Pipe used in absorption facilities must be heavy duty. Markings must meet requirements in ASTM F 667.
   2. (b) Polyvinyl chloride (PVC) distribution and fittings must current ASTM Specification D 2729. Pipe and fittings must pass a deflection test withstanding 350 pounds per foot without cracking or collapsing using the method found in ASTM 2412. Markings must meet requirements in ASTM Specification D 2729.
   3. (c) Polyethylene smooth wall distribution pipe in 10-foot length and fittings must meet ASTM Specification F 810. Pipe and fittings must also pass a deflection test of 350 pounds per foot without cracking or collapsing by using the method found in ASTM 2412. Markings shall meet the requirements in ASTM Specification F 810, Section 9.

   4. (d) The three types of plastic pipe described above must have two rows of holes spaced 120 degrees apart and 60 degrees on either side of a center line. For distribution pipe, a line of contrasting color must be provided on the outside of the pipe along the line furthest away and parallel to the two rows of perforations. Durable ink markings must cover at least 50% of the pipe. Markings may consist of a solid line, letters, or a combination of the two. Intervals between markings must not exceed 12 inches. The holes of each row may not be more than 5 inches on center and must have a minimum diameter of 1/2 inch.

      [Publications: Publications referenced are available from the agency.]

Statutory/Other Authority

ORS 454.625 & 468.020

Statutes/Other Implemented

ORS 454.615

History

DEQ 29-2025, amend filed 10/01/2025, effective 01/01/2026
DEQ 11-2004, f. 12-22-04, cert. ef. 3-1-05
DEQ 27-1994, f. 11-15-94, cert. ef. 4-1-95
DEQ 15-1986, f. & ef. 8-6-86
DEQ 9-1982, f. & ef. 6-16-82
DEQ 5-1982, f. & ef. 3-9-82
DEQ 10-1981, f. & ef. 3-20-81