RV Holding Tanks

Rule #1: Think before you panic!

A recent call I made on a customer reinforces the adage that one should

first, think things through with rv holding tank problems before hitting the panic button. This individual recently purchased a used 5th wheel and was living in it. One of the first things he told me was that he had experience with RV’s…but I am not so sure.

Once he had possession of the 5th wheel and was living in it, he discovered

his black tank dump valve was stuck open. He thought this was better than

having it stuck shut, but that is not true either.

Any experienced rv’er with a motorhome, travel trailer, or 5th wheel knows the

black tank should only be used with the dump valve CLOSED so that liquids and solids are together.

If there are no liquids in the black rv holding tank this obviously leaves only solids which eventually will lead to black tank flush problems. I was there to replace his black tank dump valve and once

I was into the job I discovered I didn’t have the correct dump valve to complete the job

therefore, I left everything as I had found it…valve open as he had been using it. By mid afternoon he called the office with what he thought was a problem, of course caused by no one else than “yours truly”.

I called him for the specifics of his problem and this is what he told me. “My toilets plugged so you must have done something to cause this.” I responded that I left the black tank valve “open” just as I had found it. I then calmly asked him this question : Are you telling me you filled your black rv holding tank since I left you? (He was assuming his tank must be full) After being presented with this question and pondering over it, he knew this likely was not the case. All he knew was that his toilet was plugged. (Yuk!)

I called on him later in the day and found the toilet full to the brim. I turned

the water off, flushed the toilet and to his chagrin it flushed normally. How

about that, I thought!

Rule #2: Toilets with angled pipe to the black tank require lots of water to properly flush.

I have also learned this the hard way with our Holiday Rambler 5th wheel. Angled

pipes from the toilet to the holding tank plug easily but the good news is its

easy to diagnose. Here’s some pointers :

– if you notice any change in the flushing action of the water in the bowl when flushing you, know you either have a partial obstruction in the pipe under the toilet OR your tank is full.

“It’s one or the other.” (A total or partial obstruction will cause the water to bubble up rather than immediately flush as normal)

– once an abnormality is noticed in flushing you should first verify the fill level of the tank. (This is not always as easy as checking the black tank monitor because they rarely perform accurately)

– After either dumping the tank or verifying it is not full, flush the toilet, hold it open and let it fill at least half way with water.Yes this is scary but you are probably in this situation anyway after ignoring the warning signs, I have just listed.Now with ample water in the bowl use a plunger and attempt to clear the plugged pipe.

Normally this procedure will be successful (if the tank is not full). If it is not successful and the tank is not full most likely this problem has been developing and growing worse with time in an rv that is not used on a regular basis, and guess what? This blockage has had time to sit and dry out…only exacerbating the problem. Your option now is to let it sit and add an environmentally safe substance that will hopefully break down the blockage. If time is of the essence someone (like me) is going to have to try to ream the blockage out or the last resort, tear things apart.

The moral of the story is as this report started out. Think before you panic. My customer

could have saved himself an unnecessary service call because it was highly unlikely

that his tank was full. Had he thought this out he could have determined he most likely

only had a blockage and he could have attempted to clear it out.

RV holding tank problems can be exasperating.. but think before you leap. In most cases, things probably are not as bad as you may think.

Read More by Ray F Oberreuter

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