State Tightens Septic Tank Rules, Favors Sewer Line Installation

State water officials, seeking to prevent ground-water contamination, adopted tougher restrictions on septic tanks Monday but stopped short of requiring developers to install sewers in fast-growing rural areas of Los Angeles and Ventura counties.

For residents of Acton and Agua Dulce, the California Regional Water Quality Board’s decision was a “moderate win,” said Charles Brink, a member of the Acton Town Council. Residents had feared that sewers would bring unwanted growth to their communities, he said.

Existing houses with septic tanks are not affected by the water board’s decision, which was prompted by studies that blamed septic tanks in part for the presence of nitrates and other pollutants in some ground water.

Septic tanks catch waste materials from household drains and toilets. Solids are trapped in the tanks while liquids are allowed to percolate through the earth and into ground water.

Under the new policy, developers who want to install septic tanks on lots between one and five acres must conduct a study and demonstrate that the tanks will not harm ground water.

The study will address such issues as development trends, the amount of sewage to be generated by the project, its impact on ground water and provisions for possible future connection to a community sewer system.

No study will be required for lots larger than five acres. Developers will not be allowed to use septic tanks on lots smaller than one acre, but individual owners of lots of less than an acre may be able to get septic tanks approved.

The new interim policy will apply until the water board concludes work on a permanent policy, probably in about a year, said Anne Saffell, chief of the board’s planning unit. She said the permanent policy will probably put more restrictions on septic tanks.

The policy adopted Monday is less restrictive than the version proposed by the board’s staff in April. That plan would have required a minimum of two acres for a septic tank and would have required developers who use septic tanks to install sewer lines in areas deemed likely to need a sewage treatment system eventually.

Under the newly adopted policy, the water board “strongly recommends” that developers install sewer lines for eventual hookup but does not require them.

“We’re trying to protect against problems down the line,” Saffell said. “It makes sense to put in a dry sewer at the time of construction rather than digging up the driveway later.”