A reservoir that receives drainage; a drain or receptacle for hydroponic nutrient solutions used for growing cannabis.
Merriam-Webster Online Dictionary
sump (noun)1.
a pit or reservoir serving as a drain or receptacle for liquids as
a) - cesspool
b) a pit at the lowest point in a circulating or drainage system (as the oil-circulating system of an internal combustion engine)
c) chiefly British - oil pan
2.
British - crankcase
3.
German literally, marsh, from Middle High German
a) the lowest part of a mine shaft into which water drains
b) an excavation ahead of regular work in driving a mine tunnel or sinking a mine shaft
4.
something resembling a sump - sink
reservoir, basin, catchment, cistern, collection chamber