Unplug your dishwasher or turn off the circuit breaker before performing any manual checks on the hose or pump.
Use a cup or bowl to scoop the water into a bucket.
If you have a small cylindrical fixture on your sink (the air gap), pop off its chrome cover and check for debris inside.
If your dishwasher drains through a garbage disposal (very common in the US), a clogged disposal will block the dishwasher drain.
If you have checked the filter, cleared the hose, and the disposal works, but the dishwasher still won't drain, you may have a failed or a broken float switch . At this point, it is usually best to contact a professional appliance repair technician.