How long does flow water last?

Could you please elaborate on the concept of "flow water" and its duration? I'm interested in understanding the factors that determine how long this flow persists. Could it be dependent on the source of the water, such as a river or a tap? Also, does the duration vary based on the volume of water flowing or the rate of consumption? It would be helpful if you could provide some examples or scenarios to illustrate this concept further. Thank you for your assistance in clarifying this matter.