DIY "Sewer Pump"
While looking for an inexpensive dumping solution for my travel trailer, I found one on the internet that works based on the "venturi effect" .  Here is a link to Tracy Oakley's website with complete instructions for construction.  My "Sewer Solution" I have constructed one and am happy with the results.  It is made from readily available parts from your local plumbing supply or home store.  Cost was approximately $40.00.
Parts List:
1 - 3" PVC Cleanout Tee - Cleanout should be threaded
1 - 3" Permanent Plumbing Adapter - Bayonet to 3" threads - Available at RV Supply
2 - 3" x 2" PVC Bushings - reduce 3" to 2"
1 - 2" x 1/2" Bushing - reduce 2" to 1/2"
1 - 2" x 1" bushing - reduce 2" to 1"
1 - 1" PVC ball valve
1 - 1/2" x 12" PVC pipe - cut into pieces as needed
1 - 1" x 12" PVC - cut into pieces as needed
1 - 1/2" PVC Cap - drill a 1/8" hole in cap to make nozzle
1 - 1/2" PVC to 1/2" thread - used to connect to 3/4" water hose connector
1- 1/2" to 3/4" water hose connector
1- 1/2" 90 degree elbow
1 - 3/4" 90 degree elbow
1- 1 1/4" x 25" Sump discharge hose (you may prefer a clear 1" hose, but this is cheap $7.98)
1 - Small can of PVC glue
1 - 3/4" Backflow preventer
Look closely to see water stream - this produces the Venturi effect.  I drilled a 1/8" hole in a 1/2" pvc cap instead of using a brass plug as Tracy Oakley did in his.
I used a 90 degree elbow on the bottom to take care of clearance issues.
The design works as described by Tracy Oakley on his website.  It is nice to be able to back fill the black and gray water tanks from the outside.  After just one use the sensors on my black tank started functioning properly.
UPDATE: 5/07/2005
I added a right angle connector to the end of the hose that can be screwed into a 3" pipe.  I constructed this using a 3" Cap that I drilled a hole thru and then glued the PVC pipe in place.   I also added a sewer connection next to the area where we park our coach at home.  It is now very convenient to wash the tanks and dump at home.
UPDATE: 8/10/2007
I updated the pump using new PVC fittings and reduced the size.  The 1/2" PVC has a 90 deg. bend to direc the water into the drain pipe with a hole drilled in a 1/2" cap as noted above to produce the Venturi effect.
New Parts List:
3" Cleanout coupling with threads to connect to ABS pipe
3" to 2" reducer
2" to 1" reducer
1/2" elbow and cap
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