If a bag doesn’t allow water in, then inversely it shouldn’t allow water out. The most durable dry bags should allow your wet items to stay wet only within your bag, without leaking to the outside. Some users have claimed that they were able to carry water in a dry bag with zero leakage to the outside. The thicker the material your bag is made of and the more secure the seams and openings, the more likely it will contain any water that may be inside. If you are transporting wet items remember to rinse your bag and air dry to prevent mildew buildup.