[Bill]

You didn't say whether your TM is new, but the current specs for all models is for 30 gallons of gray water capacity, and I have no reason to doubt it.

Unlike the float-level gauge in some motor homes, the gauge in the TM is not adjustable. But your idea of using the gallon jug is a good one. How many gallons can you put in before the FULL light comes on - and when the FULL light comes on, how many more gallons can you put in?

When the tank is over-full, it backs up into the bathtub first. Guess how I know this ???

The water heater has both a gas heating element and an electric heating element. The inside switch controls the gas heating element - the outside switch controls the electric element (though I understand that the 2003 models have a separate inside switch for the electric???) You may use either, or both at the same time. Using both, of course, will yield faster recovery as you use hot water - I often turn both of them on as I get into the shower. Normally, of course, if I am in a campground where I have paid for electricity, I use the electric element only and save the propane. But as Windbreaker noted, be sure the water heater tank is full before turning on either element! And be sure to turn both elements off before draining the tank. Same as in your house water heater - you don't want to try to heat an empty tank!

Hope this helps.

Bill