Graywater systems not meeting the requirements of 20.7.3.810 NMAC shall meet the following requirements.

1. A. The installation of separate graywater systems shall be authorized for residential units and shall be located on the lot served. The capacity of the on-site liquid waste system shall not be decreased or otherwise affected by the existence or proposed installation of a graywater system servicing the lot.
2. B. All information required in 20.7.3.402 NMAC for the issuance of a permit shall be required.

3. C. Design flows for graywater systems shall be calculated by the following:

   (1) 20% of the liquid waste design flow for the segregation of laundry waste; and

   (2) 33% of the liquid waste design flow for the segregation of the bathroom (showers, tubs and wash basin) waste.

4. D. For graywater systems on lots where the residential unit is served by a sewerage system, the minimum lot size set forth in 20.7.3.301 NMAC shall not be required.
5. E. Clearance requirements for graywater systems shall meet the requirements of 20.7.3.303 NMAC.

6. F. Setback requirements for graywater systems shall meet the requirements of 20.7.3.302 NMAC except for the following:

   (1) property lines, two feet for disposal area;

   (2) building or structure, two feet for disposal area; and

   (3) building or structure, zero feet for above ground tanks.

7. G. A treatment unit shall be required for all graywater systems. If a tank is utilized as the treatment unit:

   (1) the tank may be a single compartment;

   (2) the tank shall be sized to accommodate one day design flow; and

   (3) access to the tank shall be provided by a tamper resistant lid installed to grade.

8. H. Graywater should be utilized within 24 hours of collection unless additional treatment is provided.
9. I. Tanks installed below ground shall meet the requirements of 20.7.3.501-502 NMAC except for the requirements in Subsection G of this section. Tanks shall be protected against possible floatation.
10. J. Above ground tanks shall be constructed of solid, durable materials, not subject to corrosion or decay and shall be approved by the department. Above ground tanks shall be set on a three inch minimum concrete pad. Metal tanks shall not be authorized.
11. K. All tanks shall have an overflow drain with a permanent connection to the building drain or building sewer. The tank shall be protected against sewer line backflow by a backwater valve.
12. L. Each tank shall be vented as required by the New Mexico plumbing code.
13. M. Each tank shall have its rated liquid capacity permanently marked on the unit. In addition, a sign “GRAYWATER SYSTEM, DANGER – UNSAFE WATER” shall be permanently marked on the tank.
14. N. The disposal system shall be constructed in accordance with 20.7.3.804 NMAC.
15. O. The graywater system shall have no direct or indirect cross connection with potable water systems.
16. P. Graywater use for purposes other than irrigation or toilet flushing is prohibited. Irrigation of edible food crops except for fruit trees or nut trees is prohibited.

[20.7.3.809 NMAC - Rp, 20.7.3.811 NMAC, 9/1/13; A, 9/1/13]