With the Suburban 6 gal gas heaters, you can take a four or five minute shower. It's capable but you can't dawdle. It takes about 10 minutes to reheat a tank of water for a second shower.

Gard

Gard -

I'm gonna have to live off my 35 gal fresh water tank for a weekend.  Have you got any idea how many gallons total one of those 4 to 5 minute showers would take?

Thanks.

 Your water pump probably puts out ~3 gal/min, and depending on the flow rate of your shower head, the length and interior diameter of your plumbing, you could conceivably use a maximum of 15 gallons in five minutes. Most faucets and shower heads have restrictors, and even when fully open, will use less water than your pump's capacity. This is the reason your pump will often cycle on and off, or run at variable speeds when it's being used; otherwise it would run continuously.

So my answer would be something less than your pump's capacity, times the number of minutes it's being used. Sorry I can't be more specific. There are many variables that would effect the outcome.

You can save almost half of your shower water by getting wet, and turn off the water while you apply the soap. Then you turn the water back on to rinse off.

Gard

After all that in my other posting, there's a simple answer to your question. Take a gallon container, hold it under your shower head until its full, and time how long it took to fill. You can then extrapolate this time to a full shower. That will give you an idea of how much water you will use while taking your shower, and you can plan accordingly. 

Gard