Question on toilet overflow hole.

[Kevin K]

Will toilet overflow hole prevent gas's from escaping from black water tank.

[Donna D.]

Good question! I've never filled the blackwater tank to the point of overflowing.

Inquiring minds want to know....

[Frederick L. Simson]

Originally Posted by Donna D.

Good question! I've never filled the blackwater tank to the point of overflowing.

Inquiring minds want to know....

Is that a porcelain bowl?
My Aqua Magic V Hand Flush is plastic and does not have that feature.

However, I have filled the blackwater tank to the point of overflowing. It seeped out between the base of the toilet and the floor.

[Francesca Knowles]

I don't think he's asking about overflowing contents of the tank- his question relates to gases/odor getting into the trailer.

My bet is that there's some kind of a trap in that line to prevent gases from moving up it. Though how water would get to the trap to form the seal unless it overflows is a bit of a mystery.

Francesca

[Frederick L. Simson]

Originally Posted by Francesca Knowles

I don't think he's asking about overflowing contents of the tank- his question relates to gases/odor getting into the trailer.

True. But how would that hole facilitate "overflow" if the Black tank contents were not overflowing? What IS the purpose for having it?

[Brian B-P]

From a web page about toilet odours:
RV Sewer Odor

There are many different makers of toilets and many different models within those makers so you will have to use a little thought on this one. There is an "overflow" hole at the top of most of the plastic Thedford toilets. You will most likely never spot this overflow hole unless you get down close and look for it. It will be about 7/8" in diameter. Look for this hole somewhere near where the water enters the toilet. This overflow hole is attached to a hidden 1/2" hose that leads to the black tank in case there is a problem and the toilet starts to overflow. This 1/2" hose will have a loop in it that performs the function of a P-trap in your home plumbing system. If water evaporates from the loop then there is a direct path for "sewer-gas" to make its way from your black tank into your RV. All you have to do here is to pour some water into that "overflow" hole and that will re-establish the vapor lock function. It will not take much water, a 1/2 cup should do the trick.

Another one:
http://www.rvforum.net/SMF_forum/ind...?topic=28927.0

A lot of people don't know that many RV toilets have an overflow hole near the top rim. That overflow tube has a J trap as most drains do, but if there is no liquid in the trap, odours will come up. Most of the time there will be no liquid in the trap because how often do you let your bowl get that full?

Not all toilets have this type of system, but if they do (as Kevin's apparently does) the features and operation should be similar.

[Kevin K]

I think I will try and put some water in the over flow hole to keep the gases from coming out of the black water tank.

The question relates to gases/odor getting into the trailer from over flow hole in the toilet. Not about an over flowing black water tank coming up into the toilet.

[Francesca Knowles]

Originally Posted by Frederick L. Simson

True. But how would that hole facilitate "overflow" if the Black tank contents were not overflowing? What IS the purpose for having it?

The overflow- if that's what it is- is FOR the toilet...in case it overflows, presumably from water running into it.

Though now that I think about it...are we sure that's not what we're looking at??? A water feed for the toilet, or perhaps a rinsing port??? If this toilet is foot-actuated, there may be a second rinse-type function one gets by half-depressing the pedal.

Francesca

[Kevin K]

Found the information I was looking for.
"There is a J trap built into the base of the toilet for the overflow passage.. If the toilet gets flushed frequently enough, rinse water from under the rim should keep enough water in the J trap.. But most don't get enough use to keep the J trap filled and will need a shot of water before each trip."

[Francesca Knowles]

There ya go!

Time to add a turkey baster to the trailer tool kit...but you may NOT keep it in the kitchen utensil drawer

Francesca

[honda03842]

When we dump, I usually dump the black tank, when done close the black tank valve. Go back inside and fill the toilet up and flush, in the process getting water into the overflow. I repeat the filling of the toilet a couple of times. Go back outside and dump the black tank again before dumping the grey.

As a rule we dump about every 3 days.