Cal. Educ. Code § 17596

Continuing contracts for work to be done, services to be performed, or for apparatus or equipment to be furnished, sold, built, installed, or repaired for the district, or for materials or supplies to be furnished or sold to the district may be made with an accepted vendor as follows: for work or services, or for apparatus or equipment, not to exceed five years; for materials or supplies, not to exceed three years.