Interior designers this season are loving gray, a hue topping many a trend chart. But homeowners concerned about conserving water also are going gray.

Only a few years ago, "graywater" systems were part of the eco-underground, bootlegged by do-it-yourselfers determined to bypass onerous government regulations that made getting a legal permit to use recycled water almost impossible.

But that all has changed. The practice of diverting water from washing machines, showers and bathroom sinks to irrigate plants is coming clean.

Changes in the state plumbing code, most significantly a relaxing of regulations that lets homeowners install their own laundry-to-landscape systems without a permit in most jurisdictions, have made it easier to save water that otherwise goes down the drain.

"There's a huge amount of awareness now and a lot of people installing systems," said Trathen Heckman, executive director of Daily Acts, a Petaluma-based nonprofit that promotes green living practices and has facilitated at least 50 new systems.

"Given the drought reality we're in, we need to make sure we're using water wisely by using less and recycling as much as we can."

It's not just "greenies" tapping graywater. Cities like Cotati, Windsor, Petaluma and Santa Rosa, as well as the Sonoma County Water Agency and the county of Sonoma, all tout graywater. Santa Rosa offers rebates for qualifying systems.

Some municipalities, often partnering with Daily Acts, hold workshops for homeowners to learn how to install their own laundry-to-landscape system. Each participant gets a free kit with virtually everything needed to do it themselves. Experts provide support, even coming out to people's homes to troubleshoot.

Graywater systems are like tapping into a well without drilling. They divert untreated wastewater from bathtubs, showers, bathroom sinks and washers into pipes that carry it out into the landscape. It can be a safe and water-savvy way to irrigate fruit trees, shrubs and ornamentals, but is not recommended for root crops or edibles that touch the ground.

Graywater users need to use detergents made safe for graywater use, brands like Oasis, ECOS and Dr. Bronner's. It must be not only biodegradable but "biocompatible," without the salts that can build up in your soil. Such soaps also are available for the bathroom.

Graywater is different from "blackwater," which comes from toilets, dishwashers and kitchen sinks and contains human or organic food wastes, as well as grease and oils that could present a health risk or clog pipes.

There are several types of systems: a clothes washer system that is inexpensive, doesn't require a permit and can be a weekend project, or a more complex system for bathrooms that involves tapping into your plumbing and does require a permit.

Older top-load washing machines use 40 gallons a load, so the savings can be significant.

"A family of four can recoup anywhere from 7,000 to 15,000 gallons of water a year," said Ryan Johnson, who oversees residential projects for Daily Acts.

After a 2012 workshop, Elaine and Chuck Newman were able to install a laundry-to-landscape system themselves in 2012 that waters four fruit trees in their backyard.

Then they hired a professional installer to put in a complex system to capture water from an upstairs bathroom, which irrigates a new low-water-use landscape in front that Daily Acts volunteers helped plant.

The bathroom system involved tapping into a sewer pipe, easy for the Newmans because their old 1900 house has exterior plumbing. A switch valve diverts the graywater into a second, 2-inch pipe that extends down the side of the house and into the landscape through subsurface irrigation pipes.

Graywater can also be discharged to the ground surface into mulch basins covered with at least 2 inches of mulch, rock or soil, something the Newmans learned how to do at the Daily Acts workshop.

The Newmans ran a flexible 1-inch hose from the washing machine into the yard. As a condition, laundry systems need a valve switch, clearly marked, to divert wastewater into the sewer if the load includes diapers or clothing exposed to paint or other toxins.

Graywater flows into a series of emitter boxes dug into mulch pits filled with bark, which absorbs water to prevent it from ponding. Roots of nearby trees grow into the pit.

Advocates are excited about the potential water savings from the fledgling movement.

"You walk down the street and look at almost every house," Johnson said, "and you can see a graywater spring waiting to be tapped in a big way."

You can reach Staff Writer Meg McConahey at meg.mcconahey@pressdemocrat.com or 521-5204.