Thousand Oaks is encouraging residents and businesses to oppose a water rate hike proposed by California American Water.

The company, a subsidiary of American Water Works Co., is proposing rate increases between 5 and 25 percent depending on usage, according to the city. The rate increases will provide money for the company’s “operating, maintenance and capital costs, including costs in other water systems throughout Southern California,” the city says on its website.

In testimony before the California Public Utilities Commission earlier this year, the city said the increase is not based on the cost to provide water to customers. Also, since California American Water only serves part of Thousand Oaks, the rate increase would create “an unfair disparity in rates among customers living in the same city and consuming water from the exact same source.”

The California Public Utilities Commission is the government body that approves rates. Thousand Oaks has retained a lawyer familiar with the commission. The city estimates the rate increase would affect 47 percent of its residents.