Clean water tank shock

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benmack1

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Perhaps this question has already been answered in one of the previous discussions on the topic of sanitizing the clean water tanks.  I see that there are recipe's for shocking the tanks with a cup of bleach and some for adding a cap of bleach for normal usage maintenance of a tank.  My question is when this water containing bleach is flushed through the toilet and rinsed down the shower or sinks does it kill off the good bacteria I need in the waste tanks.  I am especially concerned about the shock treatment to sanitize the first time.  I have noticed all the threads suggesting no chemicals or enzymes need to be added to the waste tanks so I assume that means these are acting like a septic tank and there is some natural digestion going on with bacteria.  Is this correct?
 

MonacoMoe

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As far as sanitizing the fresh water tank a cup or so of bleach is great, then dump your water tank and flush out 1 time, then fill and use as normal.  As far as ruining "good bacteria"  in the grey or black tank, I haven't heard anything positive or negative about this since it is not a closed system like a septic tank that needs to have bacteria to keep the solids digesting and the liquids spilling out of the tank in a runoff field.  Since the porpose of an RV holding tank it wxactly that to hols the waste water, the only thing you have to worry about is dumping and thats it.  Bacteria good or bad is a non issue.  You can however use waste tank additives to breakdown and mostly COVER UP THE SMELLS and there are formaldihyde based or enzyme based and which type you use depends on EPA standards in the state you live or travel in.  But again the main point here is to mask the smell (IMHO). 
 

Gary RV_Wizard

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I agree - the bacterial action in the black tank in not a major contributor to waste disposal - it is  a holding tank more than a septic system.    And sanitizing the fresh tank once or twice a year is't going to impact it anyway, since you are dumping the chlorinated water when you flush it out.  And there's no need to put any of the super-chlorinated water through the black tank - you can drain it directly onto the ground through the fresh tank drain or via the gray tank system.

Normal levels of chlorination in potable water won't bother a septic system - most public water supplies are chlorinated these days anyway, so septic systems get chlorinated water all the time. It's anon-problem.
 

Carl L

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I am especially concerned about the shock treatment to sanitize the first time.? I have noticed all the threads suggesting no chemicals or enzymes need to be added to the waste tanks so I assume that means these are acting like a septic tank and there is some natural digestion going on with bacteria.? Is this correct?

First of all, you drain the santizing solution from the fresh tank and refill it with domestic water.? ?Concentrations of bleach at the level of the sanitizing solution will clean out your intestinal flora -- this is a really bad idea, especially at the start of a vacation -- so don't drink it. 

Septic action is irrelevant in the gray water tank.  The tanks are normally left open in camp, and solids are few and fine grained.

Septic action is more important in a black water tank.  This tank should remain closed until at least 2/3s full and then dumped.  This can be as long as 5-7 days.  Septic action will take place and does serve to break up solids and paper.  Muncipal engineers find that significant septic action takes place in sewage as it heads down sewers to the treatment plants.  It is not complete digestion, but it is significant in their calculations.
 

benmack1

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Thanks for the answers.  I guess my concern for killing any helpful bacteria in the black tank were based on concerns that others in the forum suggested no chemicals in the tanks was the best way and I assumed that there was some septic action ongoing to keep the smells down. 

For some reason I am concerned abou this whole process so if you will allow me to here is what I plan to do.  Please correct if I am wrong.

1) add a cup of bleach to a few gallons of water in a bucket and add to the water tank. 
2) Fill the tank (do I need to completely fill this thing with 100 gal of water?)
3) Run the shock solution through all the lines and faucets. 
4) Let sit for a few hours or overnight. 
5)  Drain the tank through the tank drain. 
6)  Flush with clean water once and drain.
7)  Refill for normal use with just water 

My concerns were the flushing the lines would get alot into the black tank.  However once I think about it there doesn't seem to be alot of reason to worry about the toilet water quality as I really don't have any plans to drink that.  I never know about my dog.  His kisses are suspicious sometimes.  Anyway, I think I get it, that there isn't much concern about this since most of the flushing of the lines is into the grey tank anyway.  I would appreciate any corrections if I have the process screwed up as outlined above. 
 

Gary RV_Wizard

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Here is a link to Clorox' recommendation for purifying drinking water (used when the water added to your tank is not known to be safe for drinking). The last line gives a stronger dose for sanitizing, which is what you refer to as "shocK".  Make sure the dosage you use is consistent with these recommendations.

Yes, you really should fill the tank, so that the chlorine solution comes in contact with as much of the tank surface as possible and also flow into the overflow line. Bacteria collect everywhere not just in the bottom of the tank.  If practical, it is best to drive the rig around the block with the solution in the tank, to splash it up on the parts that are not immersed. I don't do this myself, but it is s a good idea if you are worried about the waer system.
 
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