Sanitizing the Fresh Water

What is one of the most important things we need to sustain life? Fresh water! And how many RVers would you guess set out for camping with stale water? More than you can imagine! Very few campers know even the basics of onboard water storage and maintenance! In fact, many weekend warriors in the south, where we don’t winterize our units, might have have years old water in their fresh tank because they never use it, since they’re hooking up every weekend locally! And I’m willing to bet you would never guess that water is still safe to drink, would you?

I would like to take a few minutes in this article to address some of the points you should know, and also teach you how to properly maintain and sanitize your freshwater tank if you choose to do so. I also want to dispel some of the Facebook and Internet myths, fairy tales and total untruths. So let’s start off with that!

Part One: Myths, Fairy Tales and Untruths

Water in your freshwater tank goes bad after xx number of days, weeks, months

False!   Water does not go bad in your tank! If you found a 1,000 year old RV with a full freshwater tank, it would STILL BE DRINKABLE! According to Dr. Truls Krogh, director of the Department of Water Hygiene at the Norwegian Institute of Public Health:
“If the water is covered and of good quality to start with, in principle it can last a thousand years,” he says. This also goes for water from the faucet.

Q  So why do people sanitize it?
A  Simple, since water is a universal solvent, water in your RV freshwater tank and PEX pipes tend to take on the molecules from the plastic, resulting in a “stale” or more accurately, plastic smelling water supply.

Q  So, If water doesn’t get bad, why is there a shelf-life date printed on the bottle cap when we buy it in the store?
A  Another easy question! This is the result of a bureaucratic decision. BUT, there’s the smell and taste! The simple fact that water is drinkable doesn’t mean it still smells or tastes good!

Old water isn’t dangerous to drink but it can taste bad! THIS is one of the reasons for expiration dates on water bottles, and the reason we, in the camping world, sanitize our RV tank and pipes! Know it or not!

You only have to sanitize your fresh water system once a year

False!   One sanitizes their water supply as needed. I will sanitize my water usually once every two to three months or when the wife complains about the odor. We find ourselves more and more these days at campgrounds with full hookups, so the little water we keep in the tank can get stale. It’s not a problem when camping, just when traveling and using the water from the tank. This however, is a personal preference! If the odor doesn’t bother you, you don’t need to sanitize at all!

You Should Use a Treatment Made for RVs

False!   RV products are marketing hype and nothing but hype! If you actually check the active ingredients in almost any ANY RV product, you can duplicate them with ordinary products, sometimes at 1/50th of the cost! There are no special ingredients in RV products! All of the products sold for sanitizing your freshwater tank have one active ingredient, bleach! You can duplicate this product with a $0.99 bottle of generic bleach and some water from your faucet. All the manufacturers do is mix it for you, put on a fancy label, add a little perfume and then charge you $9.99 for a bottle of bleach water!

Using Bleach in my Freshwater Tank May Damage the Tank or Pipes!

False!   Your tank and your pipes are made from plastic. So is the bleach bottle! Even Muriatic Acid comes in plastic bottles! Plastic is immune to the corrosives found in chlorine bleach…

Bleach will make me sick!

False!   Unless you’re allergic to chlorine, bleach will not harm you in small amounts! Putting a cup or two of bleach into a 70+ gallon tank will dilute it to the point where it will not aggravate even those allergic to it! But when done properly, all of the bleach will be flushed out of the system anyway, so really no worries here!

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Part Two: The Process

So you’re ready to sanitize for whatever your reason and you bring up YouTube for some wonderfully produced videos by the actual experts, right? I mean, they look really professional, some are even dealers, and all of them have great intros and a LOT of wonderful comments! These guys HAVE to know what they’re doing! Right? Yeah, maybe not…

Don’t Be Fooled!

Almost ALL of the so-called expert videos have one fatal flaw! They DON’T SANITIZE THE FRESHWATER TANK! All these “RV Gurus” are teaching you how to sanitize your PIPES, not your TANKS! Yup, if you’re using your winterizing feature or hooking up and adding the bleach water to your water pump port, you are BYPASSING the freshwater tank!

Using the winterizing feature: The winterizing feature draws water directly into the water pump from your water bay's winterizing port. The water pump then pumps the bleach water through the pipes. The freshwater tank is, by design, protected by a backflow valve so water from the pipes cannot backup into the tank!
Using the water pump port: The same reasoning applies to the water pump port. This port is built into the diaphragm of the pump, which also prevents backflow to the tank! This is a WINTERIZING PORT, not a sanitizing port!

Does this make sense to you? Think about the winterizing process. Winterizing your RV bypasses the tanks. When you winterize, you drain your tanks and winterize the pipes. This is done by using the winterizing port in your water bay or directly at the pump. Both are actually the same process, one is just more conveniently located!

The ONLY WAY to add bleach water to your freshwater tank is via the tank fill option!

Below is my motorhome water bay. Notice I have a valve driven system with a winterizing port on the far right. My city water connection is multipurpose; it is also my tank fill. I simply move the colored valve handles to the desired position. This is the hardest system to sanitize, because you don’t have a direct access port to the freshwater tank. I have to remove my city water line, switch my valves to tank fill, and insert a line with a funnel to access the freshwater tank. I can also simply disconnect the pressure regulator, and fill an empty garden hose with the desired amount of bleach, and then connect it and turn it on. Either way works just as well.

These are a few other styles. These are the easiest to use, since they have a dedicated port directly to the freshwater tank:

So now that you see some of the different options, what you’re looking for is a port labeled, Tank Fill, or Fresh Water, or Potable Water or the like. In many cases, your hose may not actually screw on, but rather plug into the port. When the tank is full, the hose will eject itself and excess water will run out the overflow hose underneath your coach.

Now that you have an understanding about how the fresh water system actually works, let’s get down to the actual sanitizing!

Forget about everything you have already read in Facebook groups or from the “scientific” videos! I know, all the “experts” say one teaspoon of bleach mixed in every five gallons… blah, blah, blah. Let’s put all that behind us and move on! Here’s MY rule of thumb! MORE IS BETTER! THERE IS NO SCIENTIFIC MEASUREMENT!

I personally use about a quart of generic bleach in my 100 gal tank. I say generic because all you’re paying for with brand names are perfumed bleach water and fancy labels. Neither apply here! We want the basic 99% water, 1% chlorine bleach here!

If you’re lucky enough to have a separate port to fill your tank, all you need is a funnel. If you’re like me, an empty garden hose hooked up to the water supply will do.

  1. Pour the bleach directly into your tank. No, you do not need to mix it in a bucket… ugh!
  2. Connect your hose to the port and fill the tank all the way to the top and then some!
  3. Turn off the water and go inside your coach and turn on your water pump.
  4. Start at the faucet that is furthest away from the water pump. open the cold water and run it until you smell bleach. Close it and do the same with the hot water.
  5. Move on to the next faucet, toilet, shower and any other fixtures that have running water.
    NOTE: If you have a fridge with a ice maker or a stand alone ice maker connected to the plumbing, make sure they are off and bypassed before sanitizing or you’ll have to run three or four buckets of ice through them afterwards. You should also bypass any water filters as well.
  6. Move to the outside of the coach and repeat the process on your outdoor kitchen and outdoor shower if applicable. Open your low point drain for the freshwater tank for five seconds or so and then close it.
  7. Turn the water supply back on and refill the used water until it overflows again.

Theoretically, you can continue to the drain and rinse procedure in about 15 minutes because the bleach has done its job and mixed with all the water inside your coach’s plumbing. I prefer to wait about three to six hours, or even overnight if I don’t have the time to continue on, but waiting is not necessary. We are not killing bacteria or other organisms here, we are simply mixing the bleach with the stale water and evacuating it.

This entire process can actually be done successfully with no chemicals at all, but according to the customer service representative at Dow Chemical who was nice enough to do some research for me; plastic that comes in contact with chlorine bleach actually slows the leaching process of the plastics. So, the water will stay fresher, longer, and one Internet story proves true, however that’s probably the only one!

Final Step – The Flush

The flush is best to do at a campground with full hookups. I have hookups in my storage, so that’s a plus for me! Remember, do not hook up the city water! We’ll be running off the pump and tank here! Some municipalities will also allow you to dump fresh water into the street/storm drain system. Check with your local water board before making assumptions. While I can dump mine into the street at home, just a few blocks away in the next town, local ordinance prohibits any fluids leaking from a vehicle.

  1. Turn off your water heater.
  2. Hook up your sewer hose and open your gray water waste valve.
  3. Turn on your water pump.
  4. Open all sink and shower valves and run both hot and cold water at the same time – flush the toilet a few times and run your outside fixtures as well.
  5. Run all sinks and showers wide open until your pump starts to labor from running out of water. Turn off your pump at this time.
  6. Go outside and open your tank drain and any/all low point drains until all of the water runs out.
  7. Refill the freshwater tank to overflow and repeat this procedure.
  8. After the second flush, both your tank and your pipes should be both sanitized and flushed. If you still smell bleach repeat a third time, but twice should be enough.

Congratulations! You have completed the sanitization process!

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