I'll tell you what the instructions were for our 37-gallon fresh tank that came with our manual.
Pour in one quart of bleach, fill the tank (full) with fresh water, let it sit for about 30-45 minutes. Drain it, then refill it; drain it again and then it is ready to be refilled for use.
You will see a lot of variations about the amount of bleach to use, about whether or not to do the water lines and hot water heater. All I ever do if the fresh tank itself and I do it 2-3 times a season depending upon how long it has been sitting empty between trips.
Eric
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My "Basic RV" book by Bill and Jan Moeller, recommends cleaning out your fresh water holding tank annually, after a lengthy storage or after de-winterizing. A little bleach treatment will do the trick. It is also recommend doing this if you have a brand new or used RV before using it the first time.
To disinfect the tank, prepare a solution of 1 gallon of water to 1/2 cup of plain chlorine bleach. With the tank empty, use a fill spout (a new oil funnel works great) to pour in 1 gallon of solution for each 15 gallons of capacity. Note, some of the newer RV's actually have a sucker pump built into the fresh water system to refill the fresh water tank, check your owner's manual.
Once the water tank is full, open all faucets, both hot and cold, and let the water run until you can smell bleach coming from the faucet. Shut off all faucets and let the water remain in the tank and the system for 3 hours.
After three hours, drain the enter system. Then fill with fresh water.
If a chlorine taste remains in the water, prepare a solution of 1-quart vinegar to 5 gallons of water. Pour the solution into the fresh water tank and fill it with water. Let the solution set over night or drive the rig around to agitate the mixture. Flush and drain, then fill with fresh water.
Good luck!
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I just followed the instructions as my camper is sitting 5 feet from the house and I'm letting it sit over night. Super easy. Anyone have experience on how many flushes it takes to let it all out? My tank is 50 gallons so off a city connection it's a lot of flushing and draining.
It doesn't really take any flushes if you have not used an excessive amount of bleach. If you do want to rinse it out, remember that you only need to rinse the surface of the tank, not the entire volume of it, so there's no need to actually fill it up and then drain.
After you drain out the bleach water, you could put in a few gallons of fresh water, drive around the block to slosh it around, run it through the faucets, drain that and fill the tank.
I suspect that most folks who have to do a lot of rinsing have just used too much bleach; for a 50 gallon tank, you need less than a cupful since the standard health industry recommendation is 1/4 cup per 15 gallons of capacity, which is less than any of the recommendations earlier in this thread.
jeanspach wrote: Anyone use grape seed extract to sanitize? I don't like to use chlorine.
I'm a definite follower of trying to use 'green' methods of cleaning. I use vinegar on a great many things, for instance, and stopped purchasing a lot of chemicals years ago.
But I'm not sure that grapeseed does the job chlorine does. I've read about it (as you obviously have), but I not read anything definitive that shows that it will work, as a universal disinfectant, as chlorine will (which IS proven).
I have a private well in my house, so I use the bleach to clean the system (called "shock chlorination") on a fairly usual basis. I would make the exception, in this case, and use the bleach. You only need a quart of it, and only need to do this once a year (unless you're in a very warm, humid area where water sits in freshwater tank for periods of time).
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