how many liters of water is poured on land during a storm?

Answer 1

You dont measure rainfall in litres per se. You measure litres per hectare of you measure the depth of water as in mm of rain per hour.

Answer 2

First off what is the intensity of the storm, no two storm are alike, some have heavier rain than others. One storm might produce 20 liters another might produce only 10, so it depends on the intensity and strength of that particular storm.