I pulled the freshwater tank to address a few leaks around the defunct level float and decided to make the original gauge work again.

I used four inexpensive float switches and four resistors to cause the gauge to read (approximately) E, 1/4, 1/2, 3/4, and F.

The system works great! And, "welding" the cracks with a large soldering gun, and HF heat gun, a high-temp glue gun, strips cut from a milk jug, and high-temp glue sticks (eventually) produced a leak free tank!

One more check mark off the list!

Level sensors: http://www.amazon.com/gp/product/B01J3WGAYU/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

Project pictures: http://www.gmcmhphotos.com/photos/g7159-fresh-water-tank-restore.html


My Potable water tank appears to be made of a fibre glass material. Made in layers and the outside layer is crackled, like some of those lighting fixture globes. I had water in it shortly after I bought it but because of some PO modifications to the lines, such as the overflow line dumps in the bathroom?????? have not used it since.
-- This is an OEM tank for the 1974 Motorhome production run. I have toyed with the idea of using resin and Fibre glass cloth to cover the outside layer to strengthen it and maintain the water holding abilities. I have not found a tank that will fit in the same area where the OEM is without some modification to the back area including the bed area.
-- The float ( level ) system needs to be upgraded as well and I have pondered adding a top access to the tank for inspection using a marine deck plate.
Planning to eliminate the outside water hose connection on the driver side as it is made of plastic which is much too old now to trust from breaking under pressure.