1503.6 Prohibited Location — 2025 California Plumbing Code

Where there is insufficient lot area or inappropriate soil conditions for adequate absorption, no gray water system shall be permitted.

ALTERNATE WATER SOURCES FOR NONPOTABLE APPLICATIONS

TABLE 1503.4 LOCATION OF GRAY WATER SYSTEM [7]

MINIMUM HORIZONTAL DISTANCE IN CLEAR REQUIRED FROM	SURGE TANK (feet)	SUBSURFACE AND SUBSOIL IRRIGATION FIELD AND MULCH BED (feet)	DISPOSAL FIELD
Building structures1	52, 9	23, 8	5
Property line adjoining private property	5	58	5
Water supply wells4	50	100	100
Streams and lakes4	50	1005, 10	1005
Sewage pits or cesspools	5	5	5
Sewage disposal field10	5	46	46
Septic tank	0	5	5
On-site domestic water service line	5	0	0
Pressurized public water main	10	107	107

For SI units: 1 foot = 304.8 mm

Notes: 1 Building structures do not include porches and steps, whether covered or uncovered, breezeways, roofed carports, roofed porte cocheres, roofed patios, carports, covered walks, covered driveways, and similar structures or appurtenances. 2 The distance shall be permitted to be reduced to 0 feet for aboveground tanks where first approved by the Authority Having Jurisdiction. 3 Underground tanks shall not be located within a 45 degree angle from the bottom of the foundation, or they shall be designed to address the surcharge imposed by the structure. The distance may be reduced to six (6) inches (153 mm) for aboveground tanks when first approved by the Enforcing Agency. 4 Where special hazards are involved, the distance required shall be increased as directed by the Authority Having Jurisdiction. 5 These minimum clear horizontal distances shall apply between the irrigation or disposal field and the ocean mean higher high tide line. 6 Add 2 feet (610 mm) for each additional foot of depth more than 1 foot (305 mm) below the bottom of the drain line. 7 For parallel construction or crossings, approval by the Authority Having Jurisdiction shall be required. 8 The distance shall be permitted to be reduced to 1 1 ⁄ 2 feet (457 mm) for drip and mulch basin irrigation systems. 9 The distance shall be permitted to be reduced to 0 feet for surge tanks of 75 gallons (284 L) or less. 10 The minimum horizontal distance may be reduced to 50 feet (15 240 mm) for irrigation or disposal fields utilizing gray water which has been filtered prior to entering the distribution piping.