#1....if we're lucky you will be electrocuted

#2....use 100% bleach in your drinking water, even better, use fresh
pool chlorine (Na Hypochlorite)

#3....use a blow torch to get the tank real hot and then check for
leaks with the flame

That all depends upon the heretofore unstated RV you are dealing with.
For the most part though, an automatic transfer switch is only capable
of selecting one source of A/C power at any given time. Whether or not
you gen is running, is not really an issue.

Even with the largest of systems, a couple cups of bleach is more than
adequate.

Nope! If it disturbs you, then scrape it clean, and then repaint it.
Otherwise it will take more decades than you will ever expect to live,
before it ever becomes a safety issue.

I see where MsMaryPoppins@webtv.net (ChimChimery ChimChimery)
contributed:

Unless your rig is miswired there is no problem. You either have a
transfer switch or the cord plugs into EITHER the gen output or shore
power.  Not sure how a gen can get started "accidentally" - but I
suppose with kids and drunks. . . .

Will Sill
The list of subjects I care about is shrinking steadily.
Items missing from that list include but are not limited to:
- The views of moronic and anti-American nut cases
- Terminally boring and/or thoughtless commentaries.

Either you have an automatic transfer switch which would activate one
or the other power source.  Or you have a plug that either the shore
power or generator plug into.  If you have anything else, your guess
is as good as anyone's.  

For a twenty gallon tank 3/4 or 1 cup of bleach would be more then
enough.  Put in the bleach fill the tank and run the water through the
faucets until you can smell the bleach.  Then drive around to slosh
the water in the tank let it sit for a few hours or overnight.  Then
drain the tank and flush the system with fresh water.  See this site
for more info. http://www.ehow.com/how_7771_clean-rvs-water.html

The rust won't hurt anything but if you want to get rid of it and keep
it from coming back wire brush if off and then paint it with rust
preventative.  You can get that at any auto store.  Then paint with
the color of your choice.

Take care and Happy Campin...

RichA
"We Get Too Soon Olde and Too Late Smart"

..

which is under the

..

It would be really useful if you'd bothered to state the make, model,
and year of the 'Van Camper'. Or is  this  supposed to be a child 's
guessing game?  

 Anyway,  I know of at least one case where Manchester Tank replaced
the propane tank for free when tthe owner complained about _serious_
rust (flakes and pitting) on the tank on a 2 year-old class B.
Apparently they had known problems with their cleaning or priming during
one period, I'd guess around 2001.

Jim, "Hello? Psychic mechanic's hotlline?"

'02 Roadtrek C190P