Do I Need to Sanitize My Fresh Water Tank in My RV?

Do I Need to Sanitize My Fresh Water Tank in My RV?

A common question new RVers ask is: Do I need to sanitize my fresh water tank? Many new RV owners do not realize that they need to sanitize their RV’s fresh water tank. This is the only way to ensure that you have safe RV drinking water before you set out on an adventure or road trip. If your RV has been in storage for a few weeks or months, you will likely have bacteria in your fresh water system. In order to make the water potable again, you need to sanitize your fresh water tank.

Do I Need to Sanitize My Fresh Water Tank?

The answer is always yes. However, RVers who barely use water from their RVs are often neglectful of sanitizing their water tank. Simply put, they usually don’t drink that water, so they think sanitizing is just an unnecessary burden. However, you need to sanitize your fresh water tank and lines at least twice a year (every six months). You need to do it even more if you use the fresh water tank as a source for potable water. At the very least, you will be using this water for pets, for brushing your teeth and for washing up. Chances are you may use it for coffee and cooking, too, so it’s important not to skip this simple step.

sanitize my fresh water tank catIf you haven’t been sanitizing your fresh water tank, you should make this a regular part of your RV maintenance checklist. Doing it doesn’t require much money, but it does require some time. In fact, you’ll need several hours for the fresh water tank to become sanitary. You should also sanitize your fresh water tank if you notice a sudden musty or stale odor from the water. Sanitize your fresh water tank again if there has been a boil water advisory or if you’ve had recurring issues with algae or slime.

Don’t skimp on changing the filters, too. They are important for removing sand, dust and rust. However, changing the filter does not substitute a good sanitizing session. Do both and drink safely!

How Do I Sanitize My Fresh Water Tank?

Here are some quick steps to make sure your water source is clean and not a potential for disease. Read through the directions before starting this project. Also, keep in mind that you’ll need approximately 6 to 12 hours to finish the job.

What You’ll Need

  • 1 New external water filter
  • 1 New internal water filter
  • Petroleum jelly
  • 1 Funnel with a flexible clear hose and stopper
  • 1 Water filter wrench
  • Chlorine bleach (unscented and non-gel); You will need approximately 1 oz. of bleach for every 8 gallons of water capacity
  • 1 Anode (if necessary)


  1. Partially drain the fresh water tank so that it’s only half full.
  2. Sanitize the funnel and hose by filling it with a mixture of chlorine bleach and water. After 15 minutes, pour out the bleach mixture into the fresh water fill using the funnel with the flexible clear hose. Never pour straight bleach into the RV fresh water tank. If you have a bypass for the hot water tank, set it to normal use so the bleach mixture will circulate through the hot water tank.
  3. sanitize my fresh water tankFill the fresh water tank until water flows from the overflow hose (that way you know it’s full).
  4. Turn off the fresh water supply and turn on your water pump.
  5. Turn off your hot water heater. Open all faucets (both hot and cold) in the RV until you smell bleach. Turn off the faucets when you smell bleach.
  6. Turn on the fresh water supply and add 3 or 4 gallons of fresh water to the fresh water tank. Wait a minimum of 3 to 4 hours to sanitize the RV water system fully. Ideally, you should let it sit overnight.
  7. Drain the fresh water tank and refill it with fresh water until it’s full.
  8. Turn off the fresh water supply and turn on the water pump. Flush out the water lines by opening the faucets. Keep letting the water run until you no longer smell bleach. You may have to refill and rinse out the fresh water tank a second time if the smell of the bleach is still strong. If after a second rinse, you still smell bleach, you can flush the system with 1 quart of white vinegar and 5 gallons of water to rinse a third time. Some people prefer using a mixture of ½ cup of baking soda and a gallon of water in the fresh water tank until it flushes clean of bleach.
  9. Turn off the water supply and water pump. Remove the external filter. Rub petroleum jelly on the new filter before replacing the old one to make it easier to remove and replace next time.
  10. Flush the water heater next. There are many types of tanks with different configurations. In most instances these are the directions: Turn off the power. Turn off the water and the water pump as well. Open the relief valve to the water heater (very important to prevent air pressure from building up and becoming combustible). Open the drain valve to the hot water tank and drain all the water. You may need to replace the anodes if they seem corroded. Close the relief valve and the drain valve.
  11. You are now ready to refill and turn on the water source to the RV. Make sure the air is completely expelled by opening all the hot water faucets until no air comes out and water is flowing steadily. When you’re sure it’s free of air, you can turn on the hot-water heater.

Your water source is now clean, fresh and ready for drinking!

The information in this article is obtained from various sources. This content is offered for educational purposes only and does not represent contractual agreements. Nor is it intended to replace manuals or instructions provided by the manufacturer or the advice of a qualified professional. The definitions, terms and coverage in a given policy may be different than those suggested here and such policy will be governed by the language contained therein. No warranty or appropriateness for a specific purpose is expressed or implied.