Grey Water/Black Water Tank & Flush

[RMCN]

I just purchased a Carbon 36 Toy Hauler. I stayed in it 4 night this past weekend. On the 4th night I noticed the shower water was not draining. Rookie mistake I should have left the grey water valve open or check the tank level at some point. I went out to drain the grey water and pulled the handle on the right, the one under the grey water sticker. I had fluids draining but nothing consistent with a full tank and my shower never drained. So I pulled the handle on the left under the black water sticker. This seemed to drain the grey water, there was a large rush of water flowing and the shower drained.

First question: is the any chance the valves are installed backwards, incorrect labeling?

The next morning I was packing up and draining the tanks again. I hooked up the hose to the tank flush inlet, opened both tank valves and turned on the water. It seemed as if nothing was happening. No water draining out of the sewage hose, no sound of water entering the tank, and it didn’t feel as if any water was moving through the hose.

Second question: What am I doing wrong to not be able to flush the black tank via the flush port?

[tech740]

It is entirely possible, in fact likely that the labels are backwards. This is common. As far as the black tank flush the anti-siphon valve under the bathroom sink may be installed backwards. If purchased new this is also common.
This is what you would be looking for. Pay attention to the flow arrow and it should be installed with the same orientation as the pic.
https://www.amazon.com/Vacuum-Breake...s%2C176&sr=8-3

[RMCN]

Thank you for the great information. I will check that out as soon as I get home.

[Brantel]

Yep, likely labeled wrong and the anti siphon is backwards. Very common issues.

There are many RV holding tank strategies but most do not suggest ever leaving the black tank open while using the RV. This can lead to what's called a poop pyramid and end up causing big issues. Water is your friend in a black tank. I also highly highly highly suggest you use the Happy Campers tank treatment. This stuff is like magic pixie dust. It just works!

As for the grey tank, some do leave them open but eventually they will start to stink as grey tanks can end up accumulating scum, grease, etc. and end up smelling as bad or worse than a black tank. Again, I suggest leaving the grey closed and using Happy Campers in it as well. Your nose will thank you down the road and you will have less issues with your tank sensors.

Another benefit of letting the grey fill is that you can dump your black first and then use the grey to help clean out your stinky slinky hose. (Won't stink if you use Happy Campers).

[chuckster57]

If your connected to the campground sewer system and leave your gray valve(s) open, the campground system can “burp” and send wonderful aromas into your coach.

[Javi]

Originally Posted by chuckster57

If your connected to the campground sewer system and leave your gray valve(s) open, the campground system can “burp” and send wonderful aromas into your coach.

If you are going to leave the gray open I suggest forming a loop in the sewer hose like a p-trap to keep the sewer gases out of the trailer..

[Pull Toy]

Welcome to the group from Southeastern Connecticut. You will find great people, and tons of useful info here.

I keep my grey tank valve closed except to dump when almost full. I find there is less odor, and less "stuff" flushed down the sink drying out and sticking to the bottom of the grey tank. By letting the tank fill, then drain,it tends to do a better job of flushing out the tank. The same goes for the black tank. Keep the valve closed until it's time to flush, and as mentioned, dump black first then grey to clean hoses.

Good Luck,

[RMCN]

You guys are great. I’m lucky to have found this forum. Thanks for all the information.

[NH_Bulldog]

You should also check your tank configuration. Often if you have two bathrooms, one or the other could both drain sink/toilet/shower into the black tank. This is especially common with one bathroom fore and the other aft because the locations don’t allow the right pitch to separate tanks.

[Bamabox]

My labels on tanks were installed backwards. I just left them that way rather than try and peel off and replace. Not meaning to hijack the thread, but my 2017 Cougar XLite 21RBS is supposed to have 30 gal black and grey tanks. I can be hooked up to sewer, do black tank flush until the contents coming out look like spring water, sensor says empty, use the toilet 3 or 4 times, and not to be graphic, but if we were using a 5 gal homer bucket it couldn’t possibly be more than half full, so 2-3 max, and the 1/3 full sensor comes on. What gives?

[JDDilly]

That is very common. The sensors work when you leave the dealer and never are accurate again. I wait until the black tank starts to gurgle when the toilet is flushed and never really look at the sensor/gauges.

[JRTJH]

Originally Posted by Bamabox

My labels on tanks were installed backwards. I just left them that way rather than try and peel off and replace. Not meaning to hijack the thread, but my 2017 Cougar XLite 21RBS is supposed to have 30 gal black and grey tanks. I can be hooked up to sewer, do black tank flush until the contents coming out look like spring water, sensor says empty, use the toilet 3 or 4 times, and not to be graphic, but if we were using a 5 gal homer bucket it couldn’t possibly be more than half full, so 2-3 max, and the 1/3 full sensor comes on. What gives?

The holding tanks are "mounted between the chassis rails in a 6-8 inch tall space. They are "long, shallow containers with the holding tanks sensors mounted in the end of that shallow tank".. If the trailer is 1" off level (side to side" it can affect how the contents "pool" against the tank walls....

Think about carrying a quart of water in a 1 gallon "milk jug" then pour that same quart of water onto a cookie sheet with 1" sidewalls. Try walking to the sink without "splashing water over the sides of the cookie sheet... Your holding tank is "sort of a cookie sheet" and anything you "spray or flush (with a plop) into the tank will "ripple against those shallow sides" and cause the sensor that reads when wet to be wet and start reading.....

ADDED: Here is a photo of the FWT and a holding tank, probably the black tank. Note the curved sides (to aid splashing up and onto the sensors) and the long, shallow walls that "encourage sensors to read incorrectly"...

[Bamabox]

Great info and pic John. Looks like that middle tank is the black tank with a stack for the toilet. So all this being said, how can you tell when you black tank is really close to full? If you shut off the water and open the toilet flap, you can look down in there with a flashlight, but you really can’t tell much. There is a black tube, ABS I’m guessing that extends down from the toilet into the tank. When the liquid hits the bottom of that is the tank pretty full?

[JRTJH]

If you "use your ears rather than your eyes" you can tell when YOUR black tank is within 4 or 5 flushes of full. MINE might sound slightly different from YOURS, so that's why the emphasis on YOUR black tank....

When the tank gets close to full, it will start to gurgle, then start to burp, then start to "glug" when you flush.... That's the point where the roof vent stack begins to become submerged.

All of us know (or should know) approximately how long we can go with our "normal black tank usage"... if you "always get 8 days" then you can expect to get 8 days... If, at 7 days, you hear a gurgle, you know it might not be 8 this time.... If at 9 days, you still haven't heard that gurgle, you know it'll be closer to 10 or 11. Then the decision becomes, "Do I empty now or wait until the gurgles and glugs" ???

If you look back at RV history, "nails in the end of a tank to sense the contents" wasn't even a dream until the late 80's or early 90's. Since then, the only "advancements in holding tank sensors" is the color of the buttons you push to light the lights... It's the same technology being installed as OEM tank sensors that was introduced way back then....

There are "high dollar systems" that are more accurate, but for most people, the gurgles and glugs is all they need and honestly, all they're willing to spend money to install.....

So, how do I tell when to dump my black tank? When it "tells me it's full"...

[travelin texans]

You can use cleaners, digesters or any number of magic elixirs & drive yourself nuts trying to get them to read more accurate, but honestly most of us are just like John listening when you flush & you'll know when it's time.
Just a couple other suggestions.
The 1st & it's a biggy, NEVER leave the black valve open when connected to a sewer connection, leave valve closed & dump as needed or you'll have the dreaded poo pyramid due to all the liquid draining leaving solids behind, think paper mache with poo & tp!!
Number 2 use plenty of water per flush for number 2, dump more often if needed, but more liquid helps drain the solids when dumping.

[sourdough]

Bama just do like John mentioned and pay attention to the "sound" of the toilet flushing. Listen to it when you have just drained it and each time you flush until that sound changes. I wait until I see a "bubble" form when the flush lever is pushed. It's telling me "I'm getting full". I can go a bit longer but plan dumping the tanks very soon.

For us the bath gray tank fills sooner usually. On a new trailer I always use everything in the bathroom normally until I take "that" shower when the water backs into the shower pan. I log the number of days and dump all tanks according to that. You need to be aware of any changes/anomalies when doing this because on or the other could fill prematurely. We don't have kids so I can keep track of it easily. With kids or guests it might be a little more difficult. I tried using sensors when they first came out but I don't have the patience for dealing with it. I looked at the sensors on this trailer at walk through and haven't since.

[Bamabox]

Thanks guys. Great help. I had become a chronic tank sensor monitor. As you all have explained, they are pretty much fake news. Now I got my ears on.

[flybouy]

just like refueling your truck's tank. You can hear the difference before the nozzel clicks off.

[K_N_L]

Backward labels are a Keystone feature. My favorite was the aux and generator tanks were labeled backwards as well. On our first boondocking trip I put like 15 gallons in each. On the second day, I went to refill the gen from the aux tank. After about 10 minutes of pumping , the levels were not changing I looked under the unit to see that I was just circulating the aux fuel tank .

[Life-in-Him]

Great review guys.

Discovered the "Audio warning system" without the woops factor a few months back after going nuts re the pseudo accurate electrical/tronic guestimation system.

To put a few variables into why the built-in seldom works here is what we've uncovered:
1 temprature of the controller & sensors changes everything. Today @ 90° all 4 tanks show empty (less than lowest level)
Last night @ 50 fwt was 1/3, black 2/3, h#1 1/3, g#2 2/3 full.



2 water & effluent chemistry mater. Alkalinity goes one way, acidity the other. Solids vary by grease levels & types, soaps & detergants differ, you get the idea.

3 DC voltage value changes sensor readings. Ours @ 13.2 reads empty but 13.3 & up vary radically.

4 as mentioned elsewhere the cookie sheet syndrom can vary as someone walks end to end, or jacks, stabilizers etc expand-contract w/outside temps..

5 the real external cause seems to be that the measurement is a reference to 3 or 4 voltages. Having senioritis, these might be wrong but system seem to work thus: full is about 12V across all 4 sensors. 7-8V is 2/3 full across 3 sensors. 3-5V is 1/3 full across 2 sensors. 0-2V is empty.

Your voltages & sensor count may vary. ��



Having wasted days or weeks trying to chase this groundhog on the surface & throughout its burrows, it's now a challange to defeat it or get out the specialists propane response tooooool. ����