Lake Konsu (, also , , , , or ) is a lake in Estonia. It is located in the village of Konsu in Alutaguse Parish, Ida-Viru County. The water of Lake Konsu is piped to the Ahtme Power Plant, to the northwest, where it is used as cooling water.
The lake has an area of . The lake has an average depth of and a maximum depth of . It is long, and its shoreline measures . It has a volume of .