Feasibility, fluid measurement

I have a machines that have 2 DC pumps pulling fluid periodically through out the day. I want to calculate the fluid that moves through each day. Would approaching it by counting the revolutions of the pumps with a tachometer be the simplest?

rustybro:
Would approaching it by counting the revolutions of the pumps with a tachometer be the simplest?

Only if there is a precise volume delivered with every revolution. You know the sort of pump you are using. We don't.

You can get flow meters that can be fitted to pipes.

...R