my crosswave smells terrible, like mildew, even after i empty the dirty tank.

Diagnosis

The pungent, mildew-like odor in the Bissell CrossWave 1785A is caused by the accumulation of organic biofilm and stagnant moisture within the internal recovery plumbing. While you are emptying the dirty water tank, the actual internal hose and the intake manifold (the area between the floor nozzle and the tank) remain coated in a layer of slime consisting of hair, dust, and old cleaning solution. Over time, this residue traps moisture, creating a breeding ground for mold and bacteria. Because the machine uses a vacuum motor to pull air and water through these narrow tubes, the airflow pushes the scent of this decaying organic matter directly back out through the exhaust and the nozzle, making the smell apparent even when the tank is empty. You can confirm this by smelling the air exhaust vent at the rear of the machine; if the scent is strongest there, the contamination is deep within the internal recovery path.

How to Fix It

To eliminate the odor, you must perform a systemic flush of the internal recovery path using a mild acidic solution to break down the biofilm.

1. Remove the dirty water tank and the filter located at the top of the tank. Rinse both thoroughly with hot, soapy water and let them air dry completely.
2. Remove the brush roll and the nozzle assembly from the bottom of the machine to expose the internal intake port.
3. Prepare a cleaning solution consisting of 2 cups of warm water and 1/2 cup of distilled white vinegar. Do not use bleach, as it can degrade the internal rubber seals.
4. Pour the vinegar solution directly into the recovery intake port (where the nozzle usually connects).
5. Tilt the machine forward and shake it gently to ensure the liquid coats the internal walls of the recovery hose.
6. Let the solution sit for 15 to 20 minutes to break down the mold and slime.
7. Fill the clean water tank with warm water and a small amount of CrossWave formula.
8. Run the machine on the "Max" setting over a wet surface or a shallow tray of water for 2-3 minutes. This forces the internal system to flush the vinegar solution and any loosened debris into the dirty water tank.
9. Empty the dirty tank immediately after this process to ensure no residue remains.

If That Didn't Work

• Deep Clean the Filter: The filter on the 1785A often traps odors in its fibers. Soak the filter in a mixture of warm water and a drop of dish soap for one hour, rinse it thoroughly, and leave it to dry for a full 24 hours. Using a damp filter will actually worsen the mildew smell.
• Sanitize the Brush Roll: The bristles of the brush roll can hold onto bacteria. Remove the brush and scrub it with a stiff brush and a mixture of vinegar and water. Ensure the ends of the brush roll are clear of hair wraps, which trap moisture and rot over time.
• Internal Hose Flush: If the smell persists, use a flexible pipe cleaner or a thin zip-tie to gently clear any physical clogs from the intake port. Sometimes a "plug" of hair and debris is trapping the mildew, and the liquid flush cannot reach it.
• Enzymatic Cleaner: Replace the vinegar solution with a specialized enzymatic cleaner designed for pet odors. These enzymes "eat" the organic matter causing the smell. Follow the same flushing procedure as described in the FIX section.

Heads Up

• Dry the System: After every single use, leave the dirty water tank off the machine for 30 minutes to allow the internal recovery path to air dry.
• Avoid Over-sudsing: Do not use standard dish soap or non-approved cleaners in the clean water tank; excessive foam can leak into the motor housing, causing permanent odors and electrical failure.
• Filter Replacement: If the filter has been exposed to heavy mildew, no amount of cleaning will fix it. Replace the filter every 3-6 months depending on usage.
• Empty Immediately: Never leave dirty water in the recovery tank overnight. The stagnant water creates an immediate breeding ground for the smells you are currently experiencing.