LOS ANGELES

WATER has always been an issue in California. But drought conditions, not to mention worries about continued supplies of clean water, are turning water into a growth industry in California and elsewhere.

Big companies like General Electric, Siemens and Veolia Environnement of France have ambitious plans to bring water to developing countries and clean water everywhere. But many small companies are finding niches and doing well these days, too.

Puretec Industrial Water, of Oxnard, Calif., for example, “grew 34 percent last year,” said Jim Harris, the owner and president. The company, with 90 employees, leaped to $18 million in revenue from $13.5 million in 2006. “We have 4,000 customers,” said Mr. Harris, “but we have grown 15 percent or more every year since I started.”

Puretec dates back to 1965, when Mr. Harris started an industrial division of his father’s and grandfather’s water business. They were franchisees of Culligan water softeners, a residential service that removed minerals from local water to make tap water taste better.