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Water tank cleaning and refreshing 100 gallons

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RV stored in Florida for two years with Well water in tank (100 Gallons). Want to refresh and clean out house water tank. Read in an RV book:

1. Drain water tank completely refill halfway with clean water

2. Mix 1/4 of a cup of household bleach for every 15 gallons of tank capacity in a container with a gallon or two of clean water.

3. Pour this mixture into the water tank and top off the water tank with fresh water.

4. Drive the rig around the block a few times to mix the solution.

5. Pump the bleached water out of every faucet, at least a quart. Run the water through the hot water tank thoroughly.

6. Let water stand for a few hours. Then drain the entire tank including the hot water tank.

7. To remove bleach odor mix 1/2 cup of baking soda with a gallon of water and pour into the fresh water tank. Circulate that water through all faucets and hot water tank.

8. Let sit for a few days drive the rig around the block a few times then drain the system and fill with fresh water.


Any other ideas or any corrections to what I just wrote would be greatly appreciated thank you,

Mitchell Goldman

Monaco Diplomat 40' 2001

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41 minutes ago, Adam_C said:

A half tank is excessive.  Last time I did mine I used 10 gallons of bleach solution for three sinks, a shower, and an ice maker.

This is what I do, I'll rill the tank with enough water for the pump to pick up and then run each faucet both hot and cold water to push the solution through.  I'll run the hot water a little longer to circulate the solution in the tank.  

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Use plain bleach not scented or any other additives.  I don't leave it in for 1 or 2 days, I don't know if it will damage plastics etc. or infuse a taste or smell I can't get rid of.    I don't think it matters very much if you do 1/2 tank or more especially if you drive it some which I like to do.


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your formula does not meet the Parts Per Million level for sanitizing a a home and/or a well system.  Most public boards of health or the various federal and state agencies recommend 250 PPM.  To achieve that you need a CUP of bleach for every 15 gallons of water.  I checked a few references….some locales will let you get by with 200. The Clorox site is lower.  If you read the copy and paste from my Monaco manual below, it is pretty straight forward.  If you multiple the tank volume by 0.13….that is the OUNCES of bleach needed.

Next is the time.  You need a a free chlorine residual for about 4 - 8 hours….  You run the system until you get a bleach smell from every faucet or outlet….including icemaker and W/D. A quart is excessive,,…but it will work.

Water Filter.  Monaco is saying….i THINK….remove the filter housing….don’t bleach it.  I have a short bypass hose that Monaco provided. I remove the winged fittings from the filter and then install the short bypass line.  I do that for winterization also.  I would not put the bleach into the icemaker…disconnect the line….and manually open and flush it 

 You need to probably dilute the bleach in a 5 gallon bucket….maybe use a 1/4 th and fill it up and then use a hose and funnel and pour into the tank.  Do that 4 times.  You do not want to dump all the bleach in at once.  If you filled the tank about 1/3 full…then put in say half the amount the the rest at 2/3.  The final filling of the tank will do the mixing.  I would FILL THE ENTIRE SYSTEM.

As far as leaving the baking soda in…your call.  

One thing that would work….assuming you have a hose available.  This also assumes you can dump “chlorinated water” on a driveway or street.  Grass will not like it. Drop the entire tank volume.  Then hook up your hose and use the city supply to purge the plumbing.  Then mix up the neutralization solution of sodium bicarbonate in the fresh tank and then purge the plumbing ….the quart is a good rule.  Top off the fresh tank and let it sit to suit you.

There was a lot of debate over the years on the Yahoo site.  I did a lot of research and the Monaco information is correct.

Good Luck

Disinfecting Fresh Water
Disinfecting the water system with household bleach protects against bacteriological or viral contamination from common water sources. Read the following instructions completely before attempting to disinfect the fresh water system.
When to disinfect the fresh water system:
 If the motorhome is new.
 If the motorhome has been in storage.  Every three months during use.
To Disinfect the Water System:
1. Remove water filter element and re- install the filter housing.
2. Drain the fresh water tank. Close drain Valves when empty
3. Prepare a disinfecting solution using
one of the following methods:
 Combine one gallon of water and 1⁄4 cup
of household bleach. Use 1 gallon of this solution for every 15 gallons of tank capacity.
 Multiply tank capacity (in gallons) by 0.13. The result is the amount (in ounces) of household bleach to pour into fresh water tank. These methods will yield a
50 PPM (parts per million) disinfecting solution in the water system that will act as a quick-kill dosage for harmful bacteria, viruses and slime-forming organisms. Concentrations higher than 50 PPM may damage the water lines and/or tanks.
4. Pour the solution into the gravity fill opening.
5. Top off tank with fresh water. 6. Turn on the water pump in the
7. Open each faucet and run water until
you smell a distinct bleach odor. 8. Turn off all faucets and allow the
system to stand for four hours. 9. Drain the fresh water tank of the
mixed solution.
10. Fill the water tank with fresh water.
Thoroughly flush hot and cold lines with fresh water. Repeat this process until the chlorine bleach smell is no longer detected in the water.
11. Install new water filter.
Household bleach is 5.25% Sodium Hypochlorite. Higher concentrations increase PPM Ratio


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On 10/6/2022 at 6:00 AM, mitchellg2241 said:

Also is it bad to leave the bleach solution in the tank for a day or two?

You should be fine if your Dip doesn't have a Aquahot system.

The bleach will start reacting with the copper tubing in the AH, so you don't want to leave it in that for an extended time.

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Just remember to thoroughly rinse all bleach out before your wife washes her hair.  Luckily my friend's marriage is still going strong after that. 😆

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One of about 10 articles out there.  


there MAY be some Non Chlorine or Hydrogen Based “bleaches” out there that would work,…all the ones I read and skimmed say no or maybe.

In addition, the accepted standard by most Boards of Health and the CDC is to use a chlorinated bleach for disinfecting potable water supplies such as wells, as well as the potable systems in a hime or commercial building.  There are no “PPM” calculators for a non chlorinated bleach.   From  a “clean water store” site

Peroxide is not a good disinfectant in water, compared with chlorine. If you have bacteria present, you might want to use chlorine instead of peroxide, or use the peroxide to oxidize iron and sulfur odors, and install a UV sterilizer or bacteria filter as a final stage.

OK….finally from the “Bulk Peroxide” site….

How To Purify Water Using Hydrogen Peroxide – Drinking Water

The second category we’re talking about is drinking water. This is probably the most important category as you will be ingesting this water, meaning it should be completely safe and clear.

Even the slightest of impurity in drinking water can prove to be detrimental. Therefore, you should be extra cautious in this regard! Moreover, this is why you should opt for perhaps the best antimicrobial agent out there! (Edit note….are they implying use a Chlorine based product?)

What You Need

For this method, you should use 3% hydrogen peroxide. Higher concentrations may affect the pH of water itself and cause irritation or burning sensations when you drink it. DO NOT use chlorine for this method as it and its by-products are toxic to our body’s internal environment. You will require:

How to Use

When going about this approach, you should be extremely cautious of the concentration you are using. Always use it on a small sample first. In the case, it is not drinkable and you attempted it on a large scale, the water will not remain viable any longer.

Pour the 3% hydrogen peroxide into the liter of tap water. Hydrogen peroxide is an extremely fast-acting disinfectant so it should not take it long to clear the pollutants found in the water.

Once you see there is no active reaction taking place, you can try it out to see if it is drinkable and should be done on a larger scale or if adjustments need to be made.

BUT….if you buy 3% H2O2 at Walgreens, it says “use as a mouth wash” or you find “Food Grade” H2O2….then you would need 12 -15 OZ or maybe a pint.  It would need to be mixed in the tank and then immediately dispersed into the plumbing as the reaction is quick.  Chlorine, whether in drinking water or in a swimming pool depends on the “free chlorine” available or the “residual”.  The Formulas for that were posted earlier.  Once you achieve that concentration, you circulate or mix and allow the free chlorine to kill or destroy (oxidize) any bacteria.  Obviously a swimming pool doesn’t require the same PPM or free Chlorine residual…..but you will not “swim” nor ingest the 50 PPM that the agencies or CDC recommend.  You flush it out….and then use the sodium bicarbonate to neutralize (chemically) any chlorine residual (I may be wrong, but it is technically a mild, very mild HCl or Hydrochloric acid…).

 Then you are good to go….but don’t rinse your hair in it….sorry…but that was a great example. That brought back a tale.  I can tell you from a costly “experiment” that two chemists, not me….THANK GOD…did to descale a commercial cooling system that went awry when they left early to go fishing and forgot to tell the maintenance employees how to neutralize and flush the system.  We had to replace about $100k in piping and water cooled injection molding dies and the molding department was down for 2 weeks.  I later inherited those two….after the fallout….which lead to a managerial change….and I then had to keep making more repairs….as there was hidden and collateral damages throughout the entire operation.  These guys were synergistic and brilliant….but when they messed up, it was almost nuclear…..

That’s my take….options may exist…just a matter of standardization….which is what Monaco and the agencies recommend…l would stick to bleach and know the concentration and follow Monaco’s guidance….

Good Luck….



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On 10/9/2022 at 10:29 AM, Steven P said:

Just remember to thoroughly rinse all bleach out before your wife washes her hair.  Luckily my friend's marriage is still going strong after that. 😆

That's a great comment.  Wow - your friend must have over achieved in the chlorination of his system - sometimes more is not better and the unintended consequences can lead to a very bad performance review.  As the saying goes, dilution is the solution.  So rinse rinse rinse all that chlorine out when the job is done.

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7 hours ago, Frank McElroy said:

That's a great comment.  Wow - your friend must have over achieved in the chlorination of his system - sometimes more is not better and the unintended consequences can lead to a very bad performance review.  As the saying goes, dilution is the solution.  So rinse rinse rinse all that chlorine out when the job is done.

I should have mentioned he drives a Tiffin. 😜😜

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