Black water valve closed?

[klarowe]

Sorry for the newb question, but I guess that is what this section is for. I was reading through some topics to learn what I can before picking up my new toy hauler and saw a post about making sure to always leave the black tank valve closed until ready to dump (when at a site with full hook-ups). I was wondering why it is done this way? I would think that you want that******(pun intended) out of the camper as quickly as possible. My mother in law has a class A and I could have sworn that she leaves the valves open and then just flushes them out when she's ready to leave... Is there a specific reason to not leave the black tank valve open?
Thanks in advance.

[wa8yxm]

I Have heard of the infamous Poop Pyramid but I have two better reasons.

IN another thread they mention a park where the sewer backed up.... INTO SOMEBODY's RV via an open gray valve (I do admit to leaving one of my gray's open, but .. Well, Not one park I have ever been in could back it up that far).

However,,,, Have you ever seen the ads for expensive chemical treatments that show the stinky RV.. Well, I found out how to make my RV Stinky once.. In fact at the very campground Im at now but 4.5 years ago.. I left a valve open.

Yup, sewer gas backed up from the hole in the ground, and out the vent on the roof making for one very stinky RV.. Two ways to prevent this.. A water trap (Which might or might not work for assorted reasons) in the hose, however there is a problem there. OR,, close the valve.

NOTE: Expensive chemicals will NOT HELP.

Las Vegas (Or Clark Co NV, not sure which) has a law that the dump hose must slope towards the sewer inlet in a continouse downward slope. Thus putting a water trap in the stinky slinky is illegal there.. Only place I know of that has that law.. but then I'm not up on all the laws in all the places.

How do you make a water trap? Well, I use a Slunky (Sewer hose support) system to comply with the Vegas law and beacuse I like it.. All you do is end the support short of the hole in the ground, that way the hose Dips at least 4 down and forms a water trap (if the outlet is high enough)

But closing the valve works better.

My rig has 3 tanks, Gray 2 (Wash waste) empties via a 3/4 inch hose so you only need about a 1" rise for it.

[Ron3rd]

westend wrote:
There was a thread, recently, by a gal in FL that left a tank valve open and left her new trailer. While she was gone, the campground sewer system became blocked and flooded her trailer with sewage. IIRC, the trailer was a total loss.

X2. After reading that post, I won't even leave the gray tank valve open.

To the OP; the idea of dumping your black tank involves flushing out with lots of water. So even if you used the black for 1 day and there is very little in it, the best thing to do is add a LOT of water so you get a good "woosh" when you drain the black tank.

[navegator]

A good working sewer system normally has a gradient of 2%, less than that and the fecal matter and paper sotp, more than 2% the water carring the matter tends to run off leaving the matter behind.

The black water tank may or may not have a gradient built into it, so you flush the toilet and the matter hits the bottom and the water splashes away from the clumps, some matter remains some moves a short distance and the water runs off,
now the fecal matter starts drying in place slowlly and eventually will become hard as concrete, no repair shop will want to clean this mess when the toilet can no longer be used, they will replace the tank, with a higher labour cost.

Leaving the valve closed and dumping when it is 3/4 full is recomended so that most of the fecal matter and toilet paper get flushed out of the tank, and even then there will be some matter left, thats when you get a cleaning wand attached to a water hose, a back flush adapter or you install a tank fushing gismo, calculate how much water you are dumping into the toilet so that you more or less know when to dump, there are chemicals that help control odor and start decomposition of the fecal matter.

Some tank chemicals have formaldahide in them and that chemical is now being banned in some states and RV parks with septic tanks, remember the jars with specimens in biology class in high school, preserved in formaldahide, unles you want to preserve you crapp I do not recomend those chemicals!

navegator

[westend]

There was a thread, recently, by a gal in FL that left a tank valve open and left her new trailer. While she was gone, the campground sewer system became blocked and flooded her trailer with sewage. IIRC, the trailer was a total loss.

[therink]

And make sure you start the tank out with a good amount of water before dropping the trout. I start with 5 gallons clean water. The tanks are usually quite flat and wide therefore lots of liquid is needed to move out solids upon dumping.

[RoyB]

Thats what we always do is leave the BLACK WATER closed until we dump. I like to dump when the black tank is at least 3/4 full then we get a full force of water flow to help clean it out. We always dump the black first then the grey last which cleans the hoses best for us If we left it open at the camp site all the time it would only drain with a small water flow force and start building up the dreaded POOP PYRAMID... You don't want that believe me.

BUMPYROAD - I have heard the POOP PYRAMID forms from the top down in Australia... Everything must be upside-down there...

Roy Ken

[Jaxom]

Flies, gnats and other no-seeums can also get into your sewer system, then into your RV through the drains. Then you have the issue of getting rid of them.

Some have said not to dump until the tank is 3/4 full. I guess that's fine if you have tank gauges...and you trust them.

[klarowe]

Ahhh ok, that actually makes a lot of sense (so much that it's pretty sad I had to even ask... haha). I will check with her and make sure she isn't leaving hers open.

[rugermark2]

Bumpyroad wrote:
yes, do a search for "poop" pyramids.

This is exactly right. Your sani flush will not be able to clean it out either.

[Bumpyroad]

yes, do a search for "poop" pyramids.
bumpy

[popeyemth]

Because you don't have a direct shot from toilet to sewer and you don't have that tank full of water plus a bowl full of water to move things along .
Good Luck, Mike