rely on/upon

1 :  to need (someone or something) for support, help, etc. :  to depend on (someone or something) My mother relied on me for financial support. They rely on a well for all their water.

2 :  to trust or believe (someone or something) She's someone you can rely on. I relied heavily upon your advice. You could always rely on him to disagree.

3 :  to expect (something) with confidence :  to be certain that (something) will happen or exist The economy may improve next year, but it's not something you can rely on.