Thank you for your question and I understand your concern.
Generally speaking the common cause of water collecting in the vent hose is because of a restriction or blockage in the vent hose or vent cap where the vent exits outside. If the moisture being removed by the dryer cannot exhaust through the vent hose to the outside, moisture will collect inside the vent hose.
Check the outside vent for a blockage and make sure the flapper door is opening when the dryer is running. You will likely find a blockage somewhere in the vent system or a stuck flapper door.