An aquifer is a saturated permeable geologic unit that is capable of transmitting significant quantities of water under ordinary hydraulic gradients or is permeable enough to yield economic quantities of water to wells. In Jamaica, there are three general types of aquifer:
Alluvium aquifer is composed mainly of gravel and sand with some silt and clay which are deposited by physical processes in river channels or on flood plains. Limestone aquifer is composed of members of the White Limestone Group and exhibits mature karstic features such as a very high infiltration capacity, predominant subsurface drainage, and highly compartmentalized subsurface conduit flow.
Coastal aquifer is composed of raised reefs of the Falmouth Formation, which are highly karstified limestone aquifers with high permeability and low groundwater storage potential.