Help... Again...

[Sandals 123]

Hello all, thanks in advance for your help and patience again with us as we discover the ins and outs of RV life.

We are at our first campsite with full service and I have a couple of questions about Grey and black tanks.

On my 29RKS, we have a drain for the black tank at the front of the unit and a drain for the grey at the back of the unit. From what I have read, the common practice seems to be to drain the black tank and then use the grey tank to clean out the hoses.

Questions:

1. There is a "tank flush" water hose fitting in my control panel. Is this a way to flush out the black tank?

2. If I run my sewer hose from black tank to drain at my site, do I leave the shut off valve open or closed while camping?

Thanks for your help on this stinky topic.

[Canonman]

Your tank flush is for rinsing the black tank. I use the tank flush to fill the black tank prior to dumping (think about how your toilet bowl works). Then fill the black tank at least once more to rinse it out really good. Finally a few gallons to travel with so things don't get a chance to solidify
Always leave the black tank closed until you are ready to empty. Use LOTS of water. The more the better if you have it.

[busterbrown]

As Brian mentioned above, always ALWAYS leave your black tank valve closed when hooked up to a sewer connection. Otherwise you'll be playing with the "poo pyramid" problem. We, too, run a separate "black use only" water hose to the black tank flush/rinse prior to opening the valve. Water is your best friend in getting a tank clean.

When at a full hookup campground, we keep the gray tank valve open until the night before departure. THen we close it and fill it as much as possible with our night time showers. By morning, we usually have a semi-full gray tank that will clean the sewer hose after the black tank is emptied. Draining the gray tank is the last step in the process.

[MarkEHansen]

I think I have less experience than the others, but I have a couple comments. I was told never to use the tank flush hose while the black tank valve is closed, as a minor distraction could result in a back-flow out of the toilet into the floor of the trailer.

Whether you leave your gray tank valve open while at the campsite is up to you, but I would plan it such that each time you need to dump the black tank, you have a full (or nearly full, as much as possible) grey tank to provide a lot of water pressure to chase "stuff" out of the dump hose after dumping the black tank.

You can dump the black tank and then use the black tank flush system after, but to me this is more to rinse the interior of the tank, and not to clear the dump hose. I think you need a lot of non-black water to really "flush" the dump hose after dumping the black tank.

Do what's easiest for you, as long as it works

[busterbrown]

Originally Posted by MarkEHansen

I think I have less experience than the others, but I have a couple comments. I was told never to use the tank flush hose while the black tank valve is closed, as a minor distraction could result in a back-flow out of the toilet into the floor of the trailer.

Most likely, the "poo-ey" water would travel in the path of least resistance and spill out of the roof vent first while the toilet valve is closed. (<--------albeit, an equally miserable task of cleanup).

After several fill ups using the black tank rinse, most owners will know how long it takes. I am usually doing something near the gate valves during this process and pull the valve after about 5-7 minutes. My toilet bowl is directly over the black tank so I have the 'privilege' of watching the tank fill with my foot on the toilet bowl pedal.

[Canonman]

Mark is correct in pointing out that when cleaning/dumping/rinsing the black tank with the tank flush Pay Attention. This is considered "hazardous waste". If you don't pay attention you will pay the consequences. Yes, I do use the tank flush with the valve closed. No, I have not had any issues with water coming up the toilet (there's a watertight seal). Just keep your wits about you and understand this is a job that needs to be done correctly and efficiently and you'll be just fine.

[Logan X]

As stated above, whatever you do, do not leave the black tank valve open while you are camping. If you do, all of the liquid will drain out and the solids will remain and become the afore mentioned “poo pyramid.” It is very difficult to correct that mistake. Keep the black tank valve closed until you are ready to dump and the fuller the tank is when you dump, the better it drains out.

I leave the valve closed when I use the black tank flush. I use a timer to let me know when the tank is close to full. My toilet is above the tank so I can see it filling up.

[chuckster57]

Leaving the gray tank open can cause food particles to gather and cause odor issues. I dump my gray every night before staying in.

[Gegrad]

I keep all my tanks close then drain the gray tanks as needed. Then I save some gray for flushing after rinsing black tank. We don't typically camp for more than 3-4 nights max at this point, so we can go the whole run with our black without dumping. But I almost never #2 in the trailer because mine always seems to plug up no matter how much water I run through it.

[Sandals 123]

Thanks everyone for the help! Turns out that I have 2 grey tanks. One shares the drain with my black tank from the bathroom and another is for the kitchen.

I tried to hook up the water hose to the Black tank rinse connection and it seemed like there was resistance and water just leaked from the fitting. Am I missing something? I tried it with the black valve open and closed.

[Logan X]

Originally Posted by Sandals 123

Thanks everyone for the help! Turns out that I have 2 grey tanks. One shares the drain with my black tank from the bathroom and another is for the kitchen.

I tried to hook up the water hose to the Black tank rinse connection and it seemed like there was resistance and water just leaked from the fitting. Am I missing something? I tried it with the black valve open and closed.

The problem with the black tank flush could be the anti siphon valve was installed backwards. On my trailer, I followed the plumbing from the outside of the trailer to under the bathroom sink. Under the sink, the pex pipe and anti siphon valve are visible and accessible. The anti siphon valve on my trailer is connected with compression fittings that can be unscrewed by hand. There are arrows which show which direction water is supposed to flow. This is the first thing I would check, I hope it helps!

[chuckster57]

If your running the black tank rinser and nothing is coming out of the tank drain, odds are the anti siphon valve was installed backwards. VERY common from the factory. Now you just have to find it. It may be under the sink in the bathroom or behind the shower wall. If its behind the shower wall you will need to remove the faucet assembly to gain access to it.

[Canonman]

There is some back pressure (resistance) since you are forcing water through a sprayer with a rather small outlet. I notice some dripping from the hose connection and if I'm not connected just right even spraying.
You should hear water spraying into the tank. You might need to have someone listen from the bathroom or even open the toilet seal to be sure water is running into the tank. If no water is spraying into the tank you might have a problem with the backflow preventer. They have been known to be installed backwards

[PARAPTOR]

Sandals.... if this black tank flush has never worked for you may want to check and make sure the anti siphon valve, which is usually located under bathroom sink, is installed in the correct direction.

Update: looks like many of us responding at the same time. I must be the slowest typest (pecker).

[sourdough]

Have to go with the suggestions above. Maiden voyage on this trailer (read "maiden voyage, not PDI) I hooked up the black tank flush to use it. Received a shower from the blow back in 30 degree weather and 30mph winds. Took back to dealership (10 miles away from campground) and anti siphon valve was backward. Shame on me. On the PDI I asked if it had been checked and was told yes - did not insist that I actually saw it work - won't happen again.

[fable081]

Sandals - There has been a lot of great advice here.
1. If you discover it is not the anti siphon valve, I have the same unit as you and had a similar problem except it was the connection from the tank flush to the tank that was not connected. There was no sound coming from the tank yet the underbelly was filling with water that started to drain at the low point drain valves just push up on the belly to see if there is water moving. Dealer had to cut open the belly and repair.
2. Like you I have the gray water tank at the rear that is only used for the kitchen sink. Instead of dedicating another "sewer" hose I added the cap adapters that accept a 3/4 inch hose which I send to my Y coupling that has the same adapter. Sewer remains closed until it requires emptying and the sink continuously drains down the smooth interior with no "stink".

[Frank G]

Make your life simple and safe. Install one of these valves on each of your outlets. Now you can disconnect or connect without any spillage.

Part two, many people with two outlets connect each to a Y fitting and then run a line to the CG sewer. Dump Black, dump each gray close valves and disconnect.

https://www.amazon.com/Valterra-T58-...s%2C153&sr=8-9

[travelin texans]

Agree 100%!!! NEVER EVER leave the black valve open & NEVER EVER use your drinking water hose to rinse the black tank, use a dedicated hose.
My 5er had 1 black & 2 greys, 1 grey for only the kitchen sink/dishwasher & the other was for bath lavatory, shower & wash machine, this valve stayed open when connected to sewer or it would've needed dumped a couple times a day. I closed the bath grey valve a couple days prior to dumping black then opened it last as it's mostly soapy water.

[ncstan]

Originally Posted by Canonman

Your tank flush is for rinsing the black tank. I use the tank flush to fill the black tank prior to dumping (think about how your toilet bowl works). Then fill the black tank at least once more to rinse it out really good. Finally a few gallons to travel with so things don't get a chance to solidify
Always leave the black tank closed until you are ready to empty. Use LOTS of water. The more the better if you have it.

Not sure leaving the blank tank closed while doing a black tank flush is the correct procedure, my manual says to leave the black tank valve open while doing the flush. I suspect it maybe be because the water pressure from the flush might build to much pressure in the black tank and cause it to blow out through the toilet end which I'm sure nobody would want.

Just my thoughts, I open blk valve first/drain.. then open gray valve/drain.. close gray valve... then hook up the blk tank flush an and start. You'll see when the water gets clear after running the fluch for a min. or so. Close blk valve and done.

[Logan X]

Originally Posted by ncstan

Not sure leaving the blank tank closed while doing a black tank flush is the correct procedure, my manual says to leave the black tank valve open while doing the flush. I suspect it maybe be because the water pressure from the flush might build to much pressure in the black tank and cause it to blow out through the toilet end which I'm sure nobody would want.

Just my thoughts, I open blk valve first/drain.. then open gray valve/drain.. close gray valve... then hook up the blk tank flush an and start. You'll see when the water gets clear after running the fluch for a min. or so. Close blk valve and done.

This guy has done a lot of black tank cleaning tests. I found this video to be very informative. He shows the difference between leaving the valve open and leaving it closed. The link is below.

https://youtu.be/dfTd0Slt_cU