Sewage flush system

[jaybird6973]

I have a 2007 Rally Sport 5th wheel and it supposedly has a sewer flush system, but I have no idea how it works. Does anybody have any insight or a manual that gives instructions? I have a huge binder that has a small manual and it mentions it has the flush system and that is all. Outside in the cabinet with the dump valve pulls there is a lot of other stuff that I am not sure about, but nothing marked black tank flush or anything like it.

[SJ-Chris]

I think a picture showing all the valves, hookups, etc would be very helpful to people wanting to give you advice.


If you have a black tank flush it is likely a female hose connection near your valves or waste tank. The simplest black tank flushes simply allow you to fill your black tank with fresh water (don't use your drinking hose). This allows you to do an extra flush of your black waste tank. Be careful to pay attention to what you are doing... If your black waste blade valve is closed, and you are filling water into your waste tank via your flush, when the tank gets full the water is going to come flooding out somewhere (ie. either out your toilet and flood your bathroom, or up your waste vent to the roof and then rain down on you with a not so clean shower).


Usually, with your black waste valve open and your black tank flush connected with water flowing into your waste tank, you will push out a lot of extra contents from your black tank. If you close your blade valve with water flowing into your black waste tank, set a timer on your phone for 2-4 minutes and don't get distracted. Then you can open your blade valve and do a 2nd (or 3rd) flush. Helps to get everything out of your black waste tank.


Some black tank flush systems actually have a sprayer inside your black waste tank. Then, when you are running water into your black waste tank through your flush system it is spraying the walls/etc in your waste tank. This helps clean the inside even more. Where this is particularly helpful is it keeps your tank sensors clean and reading properly (1/3, 2/3, 3/3 full).


Good luck!
Chris

[jaybird6973]

Here are some photos of my water system cabinet. I have 2 water inlet female hose attachments but no black tank or sewage flush inlet. Do any of the other components look like they would be used for this function?

[Old-Biscuit]

The Black Capped Hose connection to the right of your potable water hose connection is the Black Tank Flush

Hookup garden hose to that connection, open black tank drain valve, turn on garden hose supply (should be pressure regulated)
Water goes in thru connection then UP to the Anti-siphon Vacuum Breaker Check Valve (typically located inside bathroom sink cabinet) then DOWN to the Nozzle installed in sidewall of black tank (typically opposite off tank drain outlet)
*leaving tank drain closed can result in overfilling of black tank...opps!)

[MichaelBarb]

Some flush systems have a little tube in the black tank that wipes around randomly. We had a tailer with one. You could hear it clattering. If you were unlucky to open the toilet flush valve at the wrong time a short, small spray of water would come out (learned the hard way).

[jaybird6973]

Thanks for the info. Crazy that it is not labeled as such. Do you know what some of the other functions of the items in this cabinet are? I am assuming to fill the holding tanks and also some winterizing functions.

[jaybird6973]

I don't see the anti siphon valve under the bathroom sink though.

[Old-Biscuit]

2007 Vintage....fortunate to have any labeling left



Right side wall....Waste Water (grey tank) drain valve (open) & the Sewer (black tank) drain valve

Upper back wall.....
on/off switch for pump
suction hose for winterizing using pump
Sat/Cable coax connections under the white cover

Potable water hose connection.......Black Tank Flush connection
Above them is the FILL valve (open to fill fresh water tank using potable water---hose connection)
*Close to use potable water or when using pump

Below that....Hot & Cold Water Low Point Drains



Anti-siphon Device...Black Flush can be inside a closet or hidden
RV MFG floor jockeys install where convenient for THEM not for Owners
*Device needs to be higher then toilet bowl rim

[jaybird6973]

Looks like mine was removed. I thought this was just a stub for a washing machine if installed. I will install one before using. Thanks for all of the info and your time.

[Old-Biscuit]

The 'Device' was removed and hard piped because they LEAK and flood inside of RV

It will work 'hard piped'........
The 'device' was 'required' due to possible cross contamination ---potable water/black tank liquid
Possible..........sure
Probability..........slim to none

Black tank would have to be OVERFILLED so high that the liquid level would be higher then the 'hard piped' section so it could backflow which would ALSO require the potable water pressure to collapse

Higher chances of overfilling blak tank...toilet seal fail etc

One could simply install a 'garden hose' vacuum breaker at connection in wet bay ---- $8 - $10 any hardware store

[jaybird6973]

Thank you so much. I was going to ask if I needed to replace as after researching found that they fail frequently.
You beat me to it and I appreciate your help tremendously.

[jaybird6973]

Well I finally tried the sewage flush system and it didn't seem like it worked. When i ran the water through the second inlet shown in the photo for the black tank flush, I heard water flowing in but nothing coming out of the sewage pipe. Maybe I am doing something wrong.
Another question is in the photo I provided above... does anybody know what the red rocker switch is for? It doesn't turn on or light up when switched

[delcirose]

Can not say for 100 percent for sure , but if I was a betting person I would think it is the switch to operate the hot water heater on 120V electric. Easy way to find out would be to make sure you have your hot water tank filled then go ahead and throw that switch (assuming you are also hooked to shore power) the light should light up and after a bit you should have hot water.

[jaybird6973]

I think you are right, but I believe previous owner disconnected and put a switch in the bathroom.