SANTA ANA, Calif. — California swimming pool companies just regaining their financial footing after the recession are now facing a new challenge: a devastating drought that has put the state’s ubiquitous backyard pools under the microscope.

More than three dozen water agencies and cities are cracking down on water use in swimming pools with rules that range from requiring a pool cover to prevent evaporation to banning residents from draining and refilling older ones that need repairs.

So far, the rules implemented by water districts haven’t put much of a dent in business, but those in the industry worry that could come if the drought lingers and restrictions tighten.

And, at a time when wells are running dry in some parts of the state and water-conscious homeowners are ripping out lawns, swimming pools have an image problem that could affect the business long-term if dry conditions persist. The uncertainty has pool builders looking at other bone-dry locales as far away as Australia for ways they can adapt.

“They’ve got a lot of pressure and it’s only getting hotter, it’s only getting drier,” said Alan Smith, the owner of Alan Smith Pool Plastering Inc., which drains and repairs 900 aging pools a year in Orange County.

Backyard pools range in volume from 10,000 to 30,000 gallons of water and the biggest Olympic-sized commercial pools hold more than 650,000 gallons. A typical backyard one, left uncovered, will lose an inch of water a week due to evaporation.

Thirty-seven cities or water districts statewide have implemented some level of restrictions on swimming pools, said Jennifer Persike, spokeswoman the Association of California Water Agencies.

The California Pool & Spa Association has pushed back hard and says that by the third year after installation, a backyard pool uses less water than a traditionally irrigated lawn would and using a pool cover reduces the water footprint even further. Currently, only about 30 percent of pool owners use covers, which can cut water loss from evaporation by up to 90 percent.

“What agencies … should be doing is trying to get savings across the board instead of targeting specific industries. You don’t see nurseries on the list, do you?” said John Norwood, the pool association’s president.

In southern Orange County, where new pool rules sparked anger, the water district will vote later this month to pull back the ban on filling new pools if the homeowner can show that the pool and decking would use less water than traditional turf, said Jonathan Volzke, water district spokesman. The agency has designed an interactive program so homeowners can do the math before applying for a permit.

The drought comes at a particularly bad time for the industry, which saw many pool companies go out of business during the recession while others lost up to 70 percent of their jobs. Shrinking backyard lots and a trend toward large community pools at new housing developments instead of a pool in each backyard also hurt.