Knowing how much water in the tank under the floor was a daunting experience. Our Niagara did not come with a water level gauge. In 2007 there were no companies in the US selling a gauge that would work.
But I found a company in Australia, R.V. Electronics, that sold a kit for under $50 US. A quick phone call and it was on its way. Got here in about a week too!
The kit only has two pieces (above). The sending unit with wiring loom and the gauge.
I did have to drill a hole in the water tank, and that wasn’t difficult (after measuring about 10 times to make sure I did ruin the tank). Once I was sure of the location, I drilled a 7/8″ hole. Then I cleaned all the little plastic burrs around the hole, filled the tank to flush out any debris.
Now I pushed in the probe, it was a snug fit. Turn the top nut one revolution and the probe installation was done.
Next I drilled a hole in the cabinet where I wanted the gauge mounted. Ran the loom from the top of the tank into the interior of the camper, and through the cabinet hole.
Now I plugged the wire loom connector into the back of the gauge and mounted it on the cabinet.