Lift straight up on the water tank to remove from its housing. Unscrew the cap and fill up the water tank until it reaches the maximum water line. Place the cap back on, reinsert the tank into the cleaner and restart. The cleaner will not work without water to create steam.
Examine the Bissell filter indicator that will alert you when it's time to change the water filter. When the bright green grains turn blue, it's time for a replacement.
Locate the water filter just below the water tank. You can access the filter by removing the water tank. Replace only with a Bissell water filter specific to your model. This will also remedy a clogged filter nozzle.