[Dana]

G.J.B.

We are going to disagree. I cringe when I see an open holding tank valve and a sewer hose leading from it. Maybe the coaches you are used to never have poop build in a pile, but on the ones I have had if the tank is always drained of water because of an open drain valve the stuff piles up because there is nothing to carry it away.

It has been repeated often that the best way to keep the holding tank from ending up with a pile of solids is to allow it to fill a fair amount and the high volume of water will carry the solids out. You may disagree, but you cannot change my mind on this topic.

I especially do not want new inexperienced owners to learn some of this stuff the hard way.

[Ronald]

Badfitter is no longer on this site.

[Dick]

While, in theory, the grey tank drain valve could be left open (if you also have raised the hose somewhere along the way to create a pseudo J-trap) but the black valve should never be left open. The poop pyramid (mentioned above) will form and there’s really nothing to stop it. With enough time, this can be a disaster and require work none of us want to do. Liberty owners have separate issues when dealing with only 1 tank but would still be able to use the grey bypass and the black tank remain closed if I understand their setup correctly.

[Jon]

We’ve had only one RV (our Liberty) so I’ve never had to manage separate black and grey tanks. I like having a single holding tank with grey water bypass to manage. If we were buying a new Liberty bespoke, I’d likely spec a single holding tank five gallons larger than the fresh water tank. Right now I have 200 gallons fresh and 175 holding. You can’t squeeze 200 into 175.

If we’re on FHU’s and clothes are being washed, I’ll leave the valve on the holding tank “open”. With the black and grey sources going through the single tank, I don’t worry about a “pyramid”.

If we’re dry camping without a sewer hookup, I’ll often open the grey water bypass (if I can discretely). Toilet water goes into the holding tank along with whatever else went into the toilet so there is water in the tank to help break up the solids. After a weekend of dry camping at the race track I watch the holding tank dump through a clear plastic elbow and its mostly water.

I’m on a Facebook RV Horror Stories page and some of stories about RV owners who don’t understand their plumbing systems are oftentimes difficult to read. That was the first time I heard the term “pyramid” used in reference to camping and RV’ing.

[gary]

I would like a volunteer who can determine if a pile of poop is a pyramid or a cone.

We look for accurate posts here on PC so this is an important task.

Ignore the effects of rose petals on the geometric shape because those with lesser coaches may not be able to relate to this topic.