If it's a clean dehumidifier, it's just collected water vapor. However, since I can't say what else was in your basement air like pollen, spores, gases, fumes and such, you probably do not want to put it in the tank.
75g Planted Barbs Denison, BlackRuby, Tiger, Albino Tiger, Green Tiger, Cherry, Gold, Checkered, Odessa.
NonBarbs Cardinal, Neon, RummyNose, Bloodfin Tetras, Z. Danios. 1RTS. Amano, Bamboo, Ghost & RCS. 20g Long Shrimp Tank RCS, Tiger, Amano.