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The Johnson Multiple Port Shower Sump collects water from the sink, which runs through a plastic filter tube before entering the sump tank. Once the water reaches a certain level the pump (red item in picture below) is triggered by a water level switch (black item in above below).

The sump needs periodic cleaning, depending on how often water is sent into it and how dirty that water is. It is recommended not to drain solid matter into the tank. Many use a bowl in the sink and throw the contents of the bowl away outside the camper. Cleaning the tank and, more importantly, the filter tube should keep things running smoothly.

Johnson Sump Pump



Sump Not Emptying


  • Pump Failure
  • Water Level Switch Failure
  • Clogged Exit
  • Grey Tank Full


Pump Failure

No noise at all from the pump would indicate a pump failure. Check the break for the pump on the camper breaker panel. Use a multimeter to test the power at the pump. (James Young)

If the pump ‘whirs’ but is not pumping out the water then it may be clogged. Turn off at the breaker and carefully use a small thin item to clear the intake.

(James Young)


If the pump ‘whirs’ but is not pumping out the water then it may have an air pocket. This often happens after cleaning, especially if cleaning involved removing all of the water in the sump. It is a bit hit and miss but cleaning around the pump intake (base of the pump) with a cloth usually either moves air or pushes water into the pump. It often takes me a few rounds of cleaning / switching the breaker back on to get the pump to drain the sump tank.

(James Young)


The inside of the motor can be cleaned and is sometimes the cause of the pump whirring but not taking up water.  The image below shows the black pump top and also a black tab with the screw in it. This tab is the catch to secure the motor. Pull the tab forward and turn the motor counter-clockwise then up to remove it. Check the impeller on the bottom for gunk.

(Dennis York)

johnson sump pump


Protect Sump Tank Cover

The sump tank cover can be prone to splitting at the screw holes. It is important not to overtighten the screws. The force can also be spread over a wider area by using a washer. I tighten the screws until the washer is not moveable underneath the screw head. Then back off the screw very slightly.

Ensure the wires leading out of the tank are neatly aligned when replacing the cover. The cover should fit cleanly over the top of these, the wires able to lay flat on the case underneath.

(James Young)

Sump Tank Cleaning

An old toothbrush of a bottle brush are useful for getting around the pump and switch.

(James Young)


After cleaning, run water into the sump tank to ensure the pump is working correctly prior to re-installing the cover. The pump often requires a bit of debris removal / air pocket removal after cleaning. Ensure it all works before installing the cover.

(James Young)