Here is something I picked up while surfing:
Disinfecting Fresh Water Holding Tanks - Mike RVChem.net The following is the chlorine bleach to water ratio recommended by the US EPA for disinfecting fresh water holding tank systems: 'After the system is relatively clean, it can be disinfected. Six ounces (2/3 of a cup) of liquid chlorine bleach (Clorox, Purex, etc.) should be added for each 10 gallons of water the tank will hold. This makes a very strong (200 parts per million) disinfectant solution as suggested by the United States Environmental Protection Agency. By half-filling the tank, then adding the bleach and finally filling the tank to the top, a thorough mixture of chlorine and water is assured. Every water outlet in the vehicle should be individually opened to allow the chlorine solution to run through it until the chlorine smell is noticeable. This procedure is repeated at one-hour intervals until the chlorine smell is immediately noticeable.' (Credit; Everpure Water Co.)
As for the Black Streaks: Wal-Mart sells a product, I think it is called Black Streak Remover, that I found very helpful. Spray it on and wipe it off before you wash and wax your rig.
I used the Environmental Protection Agency's recommended formula (bleach and water) to disinfect my water tank and lines, and I couldn't get the strong bleach odor (and taste) out of the system for days. I was glad I took bottled water on the weeklong trip, because the water in the holding tank was undrinkable. Whenever I washed my hands or took a shower, my skin smelled like bleach. What a nuisance! Is there a bleach substitute that isn't this bad?
After you run the bleach though,drain the system(including the hotwater tank) and refill the system with a baking soda solution(1/2 cup premixed into a gallon of water)per 40gallon tank. Now run this through all the lines for a couple of minutes each, then let sit for a day. Now drain fresh watertank,hotwater heater and lines. Has worked for me to remove the bleach problem after disinfecting!
Does RV antifreeze act like a disinfectant so that you wouldn't have to use bleach? Has anyone has ever gotten sick from NOT disinfecting the water system?
I always disinfect with bleach before the first trip after winter storage. But I'm not a full-timer, and there may be a few weeks between each of my outtings throughout spring/summer/fall. I add a spoonful of bleach when I fill my tank before each trip and so far I haven't gotten sick. My RV dealer told me that if I drain the system, leave the faucets open, pull open the low-point line drains, and drain the hot water heater (and don't screw the plug back in), that any water left in the system will evaporate and nothing will "grow" in there. IS HE WRONG?