What exactly do you mean by "stops taking water"? That the soil dries more slowly? That the plant wilts when watered? That you stop giving them water???
Slows, yes. They suck up more water while growing flowers and will naturally use less as flower production ceases. It's not a huge difference, though. I'd think it strange if they started going more than 1/3 longer between waterings. Most grows harvest before this effect becomes too pronounced. Also, fertilizer and impure water residues can build up in the soil over time, trapping moisture.