This is from my owner manual for sanitizing
Sanitize the fresh water tank and piping approximately every
three months, and whenever the motor home sits for a prolonged
period. This will discourage the growth of bacteria and
other organisms that can contaminate the water supply. Use a
chlorine/fresh water rinse as follows:
1. Prepare a solution of 1/4-cup household liquid chlorine bleach
(5% sodium hypochlorite) to one gallon of water for each 15
gallons of tank capacity.
2. Close drain valves and faucets, pour the chlorine solution into
the exterior fresh water tank filler spout, and complete filling
with fresh water.
3. Turn water pump switch ON. (Be sure you have 12-volt DC
power.) Open all faucets individually until water flows steadily,
then turn them off. This will purge any air from the lines.
4. Top off water tank with fresh water and wait three hours.
5. Drain the entire system by opening all fresh water tank
valves, faucets, and plumbing line drain valves.
6. Flush the system with drinking quality water. Let the fresh
water flow through the system for several minutes to flush out
the chlorine solution.
7. After you stop the flushing, close the tank valve, faucets, and
drain valves. You can now fill the tank with fresh water, and
the system is ready to use.
We don't have a freeze problem in our area so I normally leave water in the tank, about 1/2 full with a cup of bleach. I drive it about every 6 weeks and the water sloshes around with the motion. That is probably not a easy method with a 5'r.
2008 Bounder 38P F53 24/30K V10, 2013 Kia Soul Basic 6 speed manual, Ready Brake Elite tow system (previous equipment 1996 Pace Arrow Vision w/Acme Dolly)