Wednesday, August 29, 2012

Plumbing Mods

From the first time I looked under the curb-side dinette seat, I wondered what Scamp had in mind when they scattered fresh water system stuff haphazardly. Out of sight, yes. Out of mind, nope! With the parts in hand to install a water transfer pump, it's time to reorganize a bit under the bench. By the time I took this picture, I had the bench top removed and the convenience outlet dismounted from it's original location. Also discovered that one of the tank hold-down straps had pulled loose.

I dismounted the pressure pump and moved the tank forward almost to the grey water vent line. This moves 100 pounds of weight (12 gallons) forward about 8 inches and inboard 3 to 4 inches.

This left room to move the pressure pump to the back, shortening both lines to it. I would have re-positioned the pump differently, but I didn't want to mess with the tee in the line from the street pressure connection.

The output from the transfer pump needed to be plumbed to the tank somewhere. I was hoping to tee into the gravity fill line, but I wasn't successful creating a tee to fit the 1.25 inch smooth bore hose and the half inch outlet from the transfer pump, so I ended up with a tank fitting that I didn't trust enough to put on the side of the tank. The fitting goes into a 1.125 inch hole and then is tightened, compressing the black rubber seal.

The transfer pump pulls from jerry cans through a 6 foot long half inch flex hose. It feeds from the pump to the tank via half inch PEX. I seated the fill port with 3M 5200 sealant. The drop on the gravity fill port remains the same as it was but the gradient is less given the longer distance.

The project was a fair amount of work just to avoid pouring 50 pound jerry cans through the gravity fill port while trying to avoid the drips, but it sure is nice. 'Sides that, it's sure easier to get to the tank drain valve now that the hatch is installed.


  1. It looks great, John. And fine quality work as always.

  2. John: I very much like this mod. It is just what I have been looking for. What make and model of transfer pump did you use? And I gather the inlet just goes into a hole you cut in the top of the water tank? Bob Karrow, Oak Park, IL

    1. I got nearly two years life out of a cheap pump from Harbor Freight. It served to prove the concept. I now have a new Shurflow pump on the shelf waiting for me to get a bunch of other projects finished.