What is the effect of presumption affecting the burden of producing evidence?

The effect of a presumption affecting the burden of producing evidence is to require the "trier of fact to assume the existence of the presumed fact unless and until evidence is introduced to support a finding of its nonexistence in which event the trier of fact determines the existence or nonexistence of the fact from the evidence and without regard to the presumption." (Evid. Code, 604.) In other words, when met with "contradictory evidence," the presumption "disappears." (Craig v. Brown & Root, Inc. (2000) 84 Cal.App.4th 416, 421.)