Jerry Work
September 25, 2022

Sanitizing the Fresh Water System in Your Bus Conversion 

You never know what the visitors that stayed at the campsite you are staying in did before you arrived.  Therefore, it is best to sanitize the entire freshwater system in your bus conversion occasionally to ensure your water is safe to drink, cook with, and brush your teeth.  This article will explain one way of doing this.

The first step is to buy a new freshwater hose, as over time, they tend to get pretty nasty inside and any amount of sanitizing will not clean it completely.  For the sanitizing step, your new drinking water-safe hose and fittings will carry whichever sanitizing chemical you want to use to the rest of your bus conversions’ water system.  The two most common sanitizing chemicals are regular household bleach and hydrogen peroxide available at drug stores or pharmacies.  You can also find hydrogen peroxide just for this purpose sold under different brand names at RV supply stores.

You want to first hook the new hose (and pressure regulator) to the park’s hose bib.  At this point, the hose is empty of water.  Before you attach the other end of the hose to your bus’s fresh water tank fill fitting, elevate the open end of the hose and carefully pour two cups of either standard household bleach or hydrogen peroxide into the open end of the hose.  Either bleach or hydrogen peroxide may ruin your clothes if spilled so handle the open end of the hose with care while you connect it to the bus fresh water tank water inlet.  

You will see references to using one cup per 50 gallons of holding tank water capacity on the internet.  For our initial sanitizing, I recommend two cups for most all sizes of bus fresh water tanks.  Too much won’t hurt anything for the 30 minutes recommended here, but too little may not adequately sanitize your whole system.

Even without a sign, you can never be sure how clean your water source is.

Now you can hook the other end of your hose to the freshwater tank inlet fitting but don’t turn the water on just yet.  Before you do, drain all the water out of your freshwater tank if you can.  Normally there is a fitting on the bottom of the freshwater tank designed just for this purpose.  On my Prevost Country Coach, a covered switch opens a solenoid valve to drain the tank.  If you can’t find a way to drain your fresh water tank, you can proceed without doing that.

Also, before you turn on the water, hook up your sewer hose and drain your gray water tank so you are starting with an empty tank.  Once the gray water tank is empty, close the gray water drain but leave the sewer hose attached.  You will use it soon.

Now that both your fresh water and gray water tanks are empty and your hose with the sanitizing agent inside is attached to your fresh water tank inlet fitting, you can slowly turn on the water at the hose bib.  The incoming water will push the two cups of bleach or hydrogen peroxide through the hose and into your fresh water tank.  

You want that sanitizing water to completely fill your fresh water tank so do whatever is necessary for that to occur on your bus conversion or RV.  On mine, there is a switch that opens a solenoid valve to fill the fresh water tank with incoming water.  Once your fresh water tank is full of sanitizing water, turn off the water at the hose bib and wait for one-half hour.  You want the sanitizing water to cover all the interior surfaces of your fresh water tank and the plumbing lines leading to it.

You never know what critters have been drinking from the water spigot you are using.

Some internet bloggers or videos suggest you leave the sanitizing solution in your tanks and lines overnight.  And some will tell you to bypass the hot water tank.  No need to do either of those.  The National Institutes of Health say the sanitizing solution will do its work in one-half hour.  One-half hour of exposure to the sanitizing water will not damage the hot water tank, either.

After one-half hour has passed, turn on your water pump.  This will cause the sanitizing water to flow from your fresh water tank through your plumbing lines up to and through your faucets as you turn them on.

One at a time, turn on each of the hot water faucets so the sanitizing water will flow into your hot water tank(s), out through your faucets, and into the drains where that sanitizing water will enter your gray water tank.  Let those hot water faucets flow for four to five minutes each to be sure the sanitizing water has displaced all the water in the hot water tank(s) and has touched all the plumbing lines leading from the tank to the open faucet.  

Check to make sure you have used less than half the sanitizing water in your fresh water tank at this point.  If you have used more than that, carefully remove the hose from the fresh water tank inlet fitting and also from the hose bib.  Once the hose has drained of all water, connect it back to the hose bib, carefully pour in more bleach or hydrogen peroxide, reattach the hose to the bus fresh water tank inlet fitting, and refill the fresh water tank with sanitizing water.  Turn off the incoming water at the hose bib once the fresh water tank is full again.

Now start sanitizing the cold water lines and faucets by turning them on one at a time for about two to three minutes each.  Remember that your cold water lines come directly from your tank and not through a water heater, so the solution will come to the faucets sooner. Keep an eye on the level in the gray tank.  If it approaches full, drain it again.  By the time you are through you want sanitizing water to have reached every plumbing line, every fitting, the hot water tank(s), and all the surfaces in your gray water tank.  

If you have a way to attach your old hose to a fitting that will allow the sanitizing water to flow through it, do that.  While it won’t fully sanitize the old hose, it will clean it somewhat.  It is best to relegate that old hose to garden work and only use your new hose for your new, clean fresh water system in the bus.  

Wait another 30 minutes.

Now you can empty the gray water tank and with the water pump on, turn on all the faucets in the coach at the same time until the fresh water tank is nearing empty.  Don’t run your water pump dry, so be sure to close all the valves and turn off the water pump before you run out of water in the fresh water tank.

Congratulations!  You now have a clean and sanitary fresh water system all the way through the whole bus.  

Article written by Jerry Work

Jerry Work spent his professional career in technology management, first as the founder and CEO of two moderate-sized computer software companies and then as the Associate Laboratory Director for the Pacific Northwest National Laboratory (PNNL), one of the DOE multi-program laboratories. At PNNL, in addition to overall Laboratory management, he oversaw the laboratory’s work in the energy, transportation, medical and information technologies.

After retirement, he and his wife Sharon purchased a Beaver Patriot motorhome and began a cold turkey four years of full-timing which they enjoyed greatly. They then purchased a 1907 former Masonic Temple in rural Southern Oregon, restored the building and remodeled it into his studio and gallery on the first floor and living quarters on the second floor. There he designs and handcrafts fine furniture. He is well known for his many articles and tutorials about how to get the most from Festool and other-high end woodworking products.

They purchased the first of what became two fully restored GMC motorhomes, those iconic and swoopy front-wheel drive units from the 1970’s. They found the second of their two GMC’s in an air-conditioned building in Naples, FL, with just 11,000 miles on the clock following a ground-up restoration in 1984. Both of those motorhomes found their way from Mexico to Alaska and from the West to the East coast. He wrote extensively about his experiences with GMC’s and gave many a presentation at GMC club events over the years.

A few years ago they decided to go back out on the road again for longer periods of time than they could support in the GMC motorhomes so purchased a low mileage 1997 40 foot Country Coach Prevost bus conversion which is now home for more than six months out of the year. Visitors always welcome no matter where in their travels is their motto.

You can reach Jerry Work by email at:

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