Cal. Pub. Cont. Code § 20483

(a) All bids for construction work shall be presented under sealed cover and shall be accompanied by one of the following forms of bidder’s security which amounts to 10 percent of the bid:
1. (1) Cash.
2. (2) A cashier’s check made payable to the legislative body.
3. (3) A certified check made payable to the legislative body.
4. (4) A bidder’s bond executed by an admitted surety insurer, made payable to the legislative body.
  The amount so posted shall be forfeited to the municipality if the bidder does not, within 15 days after written notice that the contract has been awarded to the bidder, enter into a contract with the municipality for the work. Upon an award to the lowest bidder, the security of an unsuccessful bidder shall be returned in a reasonable period of time, but in no event shall that security be held by the legislative body beyond 60 days from the time the award is made.
(b) The faithful performance of the contract shall be secured by an undertaking in that penal sum as the legislative body requires, but not less than 25 percent of the contract price, satisfactory to the legislative body. When the proceedings include the acquisition or construction of works, appliances, or improvements to be owned, managed or controlled by a public agency other than the municipality making the acquisitions or ordering the work done, the legislative body of the municipality may require that the undertaking also inure to the benefit of the public agency to the extent of its interest in the entire project. The contractor shall also furnish a labor and material bond as required by law in a sum not less than 50 percent of the contract price.