§ 86.168. Industrial, commercial, or institutional use of graywater.

(a)

Graywater systems used for industrial, commercial, or institutional purposes must be designed to ensure that 100 percent of the graywater will be diverted to the City of San Marcos wastewater collection system or an approved on-site sewage facility during periods of non-use of the graywater system. The discharge from the graywater system must enter the wastewater collection system through an approved backflow prevention device.

(b)

All graywater systems used for process water must be reviewed, approved and permitted by the city prior to installation.

(c)

An industrial, commercial, or institutional graywater system may only be used for the following activities:

(1)

Process water. Graywater used for industrial, commercial, or institutional purposes must be treated to a standard that allows the graywater to be used in operational processes.

(2)

Landscape maintenance. If graywater is used for landscape maintenance, the graywater must meet the following standards.

a.

If the graywater will be applied in areas where the public may come into contact with the graywater, the graywater must meet the following standards:

1.

Fecal coliform, 20 colony forming units (CFU)/100 milliliters (ml), geometric mean; or

2.

Fecal coliform (not to exceed), 75 CFU/100 ml, single grab sample.

b.

If the graywater will be applied in areas where the public is not present during the time when irrigation activities occur or disposed of for other uses where the public would not come into contact with the graywater, the graywater must meet the following standards:

1.

Fecal coliform, 200 CFU/100 ml, geometric mean; or

2.

Fecal coliform (not to exceed), 800 CFU/100 ml, single grab sample.

(3)

Dust control. If graywater is used for dust control, the graywater must meet the standards in paragraph (2)b. of this subsection.

(4)

Toilet flushing. If graywater is used for toilet flushing:

a.

The fecal coliform levels must meet the limits in paragraph (2)a. of this subsection; and

b.

All exposed piping and piping carrying graywater within a building must be either purple pipe or painted purple; all buried piping installed after the effective date of these rules must be either manufactured in purple, painted purple, taped with purple metallic tape, or bagged in purple; and all exposed piping must be stenciled in white with a warning reading "NON-POTABLE WATER."

(5)

Other uses. If graywater is used for other similar activities where the potential for unintentional human exposure may occur, the graywater must meet the fecal coliform limits in paragraph (2)a. of this subsection.

(d)

Graywater used for industrial, commercial, or institutional purposes must be monitored for fecal coliform at least monthly in areas where the public may come into contact with graywater and the records must be maintained at the site. These records must be readily available for inspection by Texas Commission on Environmental Quality and/or the city for a minimum period of five years.

(Ord. No. 2010-39, § 1, 8-3-10)