Conversion vendor units may use either portable waste holding tanks approved by the department of health or permanently mounted waste holding tanks.

1. (1) All portable waste holding tanks must be listed for the intended use and used per their listing.

2. (2) All permanently mounted waste holding tanks must meet the following specifications:

   1. (a) Tanks must be listed for the intended use, installed per their listing, and be securely installed to prevent displacement during transportation;
   2. (b) Tanks must be easily removable for service, repair or replacement without having to remove any permanent construction;
   3. (c) Neither the inlet nor vent fitting may extend downward into the tank more than 1-1/2 inches;
   4. (d) The drain opening must be located at the lowest point of the tank;

   5. (e) Tanks must be vented at the highest point in the top of the tank by one of the following methods:

      1. (i) A 1-1/4 inch diameter vent pipe;
      2. (ii) A continuous vent serving as a drain from one additional fixture provided the drain portion is increased one pipe size larger than the connected trap arm;
      3. (iii) Two or more vented drains when at least one is wet-vented and each drain is separately connected to the top of the tank;
   6. (f) A fullway termination valve must be installed in the tank; and
   7. (g) No drain connection may be made between liquid and body waste holding tanks upstream of fullway termination valves.

[Statutory Authority: Chapter 43.22 RCW. WSR 99-18-069, § 296-150V-1590, filed 8/31/99, effective 10/1/99.]