A sump refers to any location that is used to collect drainage or excess water in order to avoid flooding of other areas. Sumps are necessary in both surface and underground mining.

Other than to avoid flooding, mine water collected in a sump may be:

• treated if necessary before being discharged to avoid environmental concerns
• used for dust control, reclamation or make-up water in a processing plant

Sumps are usually rectangular in shape but are made to fit the contours and topography of the mine site. It is recommended to use when possible a series of sumps for greater efficiency. Water can be then pumped in stages from the deepest sump to the surface at a lower energy expenditure.