There is provided a container for absorbing water vapour from ambient air, the container having an opening to permit water vapour to enter the container, a perforate shelf positioned above the base of the container and having a water-absorbing agent disposed thereon for absorbing water vapour, and an airway which allows air to flow into the region of the container beneath the shelf, wherein the container comprises an indicator for providing information on the operation of the container, the indicator operating when the liquid in the container has reached a predetermined level.