By Russ & Tiña De Maris
Here are sure signs you need to disinfect your RV fresh water system:
- Your significant other takes a drink of water and their face wrinkles up like a raisin.
- You take a shower and come out covered with algae.
- You fill up your fresh water tank—and then notice a sign warning a “boil water advisory is in effect.”
Really, if your rig has been snoozing all winter and you remember that you forgot to drain the system down, aside from fixing broken pipes, it’s not a bad idea to do a disinfect. It only takes about one mouthful of “Yecchh!” water to convince you that water can go stale. What to do? Well, this is the same trick we recommend before you use the water system on any “new to you” RV.
Step by step
1. Completely drain the fresh water holding tank. Fire up the water pump and open taps until all water is out of the system. If your water heater is “in the circuit” (meaning not winterized, but holding water), drain it too, using the drain cock on the heater. Big fat caution: Make sure the water is COLD before draining it.
2. Determine the fresh water tank capacity. Easy enough if you have an owner manual. If not, measure the fresh water tank. Break down the feet and inches to decimals, e.g., a 4’6″ run is 4.5′. Multiply the height, width, and depth figures and you’ll have the tank’s capacity in cubic feet. Now multiply the cubic feet by 7.48051945 and voila! You now know the capacity in gallons.
3. Using unscented household bleach (8.25% of sodium hypochlorite) and a clean container (a cleaned up juice jug or empty gallon drinking water jug is ideal), mix up a solution in this way: For each 15 gallons of tank capacity, pour in 1/4 cup of bleach, then top off the jug with fresh water.
4. Make sure your fresh water drain valve is closed (and the water heater, if applicable), and pour this bleach solution into the holding tank. Now completely fill the fresh water holding tank with clean, fresh water. At this point, if you can, move your RV around the block to thoroughly swish and mix the solution in the tank.
5. Turn on the water pump and pump the bleach solution through all the plumbing. You’ll know when you’ve pumped enough as you should smell the bleach solution at the fixture. Let solution stand in the plumbing and fresh water tank overnight. Next day, drain the fresh water tank (and again, the water heater, if applicable), and refill the fresh tank with clean, fresh water.
Get rid of that yucky chlorine taste
If you’re concerned about the remaining chlorine taste or odor, mix up a solution of 1 quart of cider vinegar for every five gallons of tank capacity and dump it in the fresh tank, repeating the same process you did for the bleach job.
Ever get caught somewhere with a dry tank and need to use surface water in an emergency? Or have to use possibly contaminated or questionable water in any emergency? Here’s how you can safely do it.
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##RVT1201


I wish all articles like this one with step by step how-to-do-it was printable.
Hi, Linda. Can you right-click on it and then select Print? Or try Ctrl+P and print it? I hope one of those works for you. Have a great day. 😀 –Diane at RVtravel.com
Thank you, Russ and Tina! What a great article! I plan to do this before we head to Alaska. In the meantime, I have been using a “water freshener” by Camco instead (https://a.co/d/6m0KRHr). Have a great week and safe travels!