I’ve run across a lot of misuse of “amount” lately and thought I’d give a quick tip for when to use “amount” and when to use “number.” In short, if you can count the thing you’re talking about, you’ll generally want to use “number.” If it’s a collective thing that you would never assign a number to, you’ll use “amount.”
So for example, you would never say “I have seven water,” and so it’s correct to say “I was so parched that no amount of water would slake my thirst.”
But you might say “ten thousand golden daffodils,” and so you would never say “I had never seen that amount of daffodils in my life.” Instead, you would say “I had never seen that number of daffodils in my life” (or, since that’s awfully stilted, “I had never seen so many…”).
A minor point of possible confusion is when you’re taking a collective noun like “water” and parceling it out into countable portions. If you’re talking about cups of water, then the modifier here attaches to “cups” and not “water.” Since you can count cups, it would be correct to write about the number of cups rather than the amount of cups of water.
For a related topic, see my post of six months ago on the distinction between “less” and “fewer.”