How to actually flush out the black water drain line

JimboFunFinder · 05-13-2019, 09:06 PM

Hi!
I have a 2016 F281BIKS that came with three holding tanks. The rear most is the black water, the next is the grey for the shower and the front most tank (still behind the wheels) is for the kitchen sink. The black gate valve is under the belly cover near the rear tank and the 3" pipe then runs exposed toward the wheels under the frame. The two grey water tanks have separate gate valves (1 1/2 inch?) and are wyed together to dump into the 3" drain line below the two grey tanks. The sewage connection is even further toward the wheels (in the direction of the front of the trailer). This means that the grey water never flushes out the entire 3" line since the grey water is 'down stream' from the black gate valve. We have never had a trailer before where the grey water did not flush out the black yuck remaining in the 3" pipe. Is there any reasonable way to plumb some water into the rearmost part of the 3" line so that I can better flush it out?
I realize now that I am writing this that I should have added a photo which I will try to add later.
Thanks for any suggestions!

profdant139 · 05-13-2019, 09:43 PM

Your trailer should have a black tank flush fixture -- does it? If so, run fresh water into that fitting. First, dump the black water, of course. Then flush the black tank thoroughly. Run fresh water for a minute with the black valve closed, and then open the valve. Do this about three times. Then turn off the water. (You should be using a special hose for this, by the way -- don't use your good hose!)

Now that the black tank is clean as a whistle, open the gray tank valves.

If you want to be extra careful, run some water in the sink with the gray valves closed and then open the valves to really flush the lines.

I hope this is helpful and not too obvious! Sorry if I am telling you stuff you already know.

JimboFunFinder · 05-14-2019, 11:21 AM

Thanks for the quick response! Yes, my FunFinder has a clean out nozzle on the black water tank but it seems that most of the campgrounds we go to do not have a hose with a threaded end. Most are just a cut hose for rinsing off the concrete or squirting in the flexible sewer hose from the trailer. I have attached two photos I hope so you can see my issue.
Don't worry about insulting my knowledge as I can always stand to learn again.

profdant139 · 05-14-2019, 11:33 AM

Aha! If there is no threaded connection available, use a Water Thief!

https://en.wikipedia.org/wiki/Water_thief

But don't do this in the campground -- do it at the dump station. Use your water thief to hook up your rinse hose to the NON potable water supply. There is often a potable supply in the same general area. Don't put the rinse hose on that one!

Also, note that a water thief often leaks a little -- the pressure of the water going in can sometimes squirt out the inflow end of the hose. No big deal, but try not to get wet. Turn on the non potable supply slowly. Don't ask me how I know this.

Hope this helps.

JimboFunFinder · 05-14-2019, 11:46 AM

Thanks for the info on the Water Thief! I will not ask how you know!
I will need to get one but this is not my current problem. It is that the hoses at the dump stations connected to the nonpotable water do not have a thread at the end. The end is just a hose which has been cut.

profdant139 · 05-14-2019, 12:12 PM

Exactly! So you take the unthreaded end of the water thief. You jam it onto the cut end of the rinse hose. The other end of the water thief is threaded. You attach your threaded rinse hose to that end. And then you attach the outflow part of your hose to the rinse port on the side of the trailer.

Here is a one-minute video someone posted:

https://www.youtube.com/watch?v=WGfJ...b_channel=Seim

profdant139 · 05-14-2019, 12:15 PM

You know, I suppose you could also carry a small hose clamp -- just to make sure there is no backflow spillage at the unthreaded connection. Jam the water thief/water bandit onto the cut hose. Slip the hose clamp over the joint between the hose and the water bandit. Tighten your hose clamp with your handy screwdriver.

Might not be necessary, but I just might put a hose clamp into my toolbox for exactly this purpose!

profdant139 · 05-14-2019, 12:18 PM

One more thought -- we have often used our water thief to fill our fresh water tank from campground faucets that lacked a threaded connection. And then we use the same water thief to, once in a while, to deal with the dreaded "cut hose" issue at the dump station.

I then have to wash the water thief very carefully, before using it again for fresh water.

But a light slowly dawns -- I could carry two of these little guys!! They are cheap and small. I am pretty sure that most Walmarts carry them in the RV aisle.

JimboFunFinder · 05-15-2019, 04:41 PM

Thanks! How might I improvise to get water into the tank flush system when I cannot connect to a hose?\

For example, could I somehow have a hose that would connect between the outside spray port and the tank flush connection? Then I could turn on my water pump and get water into the holding tank.

profdant139 · 05-15-2019, 05:41 PM

OK -- so now let's assume you are at a dump station that has no water at all. That is rare, but it does happen.

In that case, first dump your black tank. Close the valve. Use the toilet flush lever to put water into the black tank. Dump the tank again.

Then dump the gray tank and close the gray valve. Run water in your sink to put water into the gray tank. Dump the gray tank again.

JimboFunFinder · 05-15-2019, 05:46 PM

Okay, that would work! Thanks!
I also just ordered the brass spray port fitting and will try connecting it up with a short hose to the tank flush port to see how that would work. I am thinking there is a nozzle inside the tank which may help in cleaning it out.

Eagle · 05-16-2019, 11:49 AM

Quote:

Originally Posted by profdant139

OK -- so now let's assume you are at a dump station that has no water at all. That is rare, but it does happen.

In that case, first dump your black tank. Close the valve. Use the toilet flush lever to put water into the black tank. Dump the tank again.

Then dump the gray tank and close the gray valve. Run water in your sink to put water into the gray tank. Dump the gray tank again.

Although I've never had to do above (GREAT IDEA BTW) it is another reason to carry water in your fresh water tank besides for road bathroom use, washing hands after changing a tire, or having to dry camp in a parking lot or out in the boondocks.

JimboFunFinder · 05-16-2019, 12:14 PM

Thanks! I'll let you know whether it is successful. My wife says a lot of my thinking is 'different'; I prefer to say outside the box! I always make sure I have some water in the tank unless storing as we have needed it more than once, including campgrounds which had the water shutoff when we arrived because their well pump had failed.
One of my dreams is to get up to SD to see Mt Rushmore, the Badlands and the other places. Not sure we will make it this year but I have wanted to go since I was a boy and saw North By Northwest! I have been blessed to visit Yellowstone three times in my life.

profdant139 · 05-16-2019, 12:35 PM

Jimbo, South Dakota is a great goal -- but there is a lot of great stuff much closer to home! Your signature says that you are in Southern Calif -- I am in Orange County, near Long Beach. If you have a few minutes, feel free to cruise around in our blog:

Look, Mom, We're Camping!

Much of our camping has been in the Sierras, both on the west side and the east side. In addition, we've been all over the western US and western Canada. The sky is the limit!!

Eagle · 05-16-2019, 04:14 PM

Quote:

Originally Posted by JimboFunFinder

Thanks! I'll let you know whether it is successful. My wife says a lot of my thinking is 'different'; I prefer to say outside the box! I always make sure I have some water in the tank unless storing as we have needed it more than once, including campgrounds which had the water shutoff when we arrived because their well pump had failed.
One of my dreams is to get up to SD to see Mt Rushmore, the Badlands and the other places. Not sure we will make it this year but I have wanted to go since I was a boy and saw North By Northwest! I have been blessed to visit Yellowstone three times in my life.

Should you find yourself planning a trip to the Black Hills area, let me know and can give you a few pointers, places to see/avoid, etc.

I usually visit the Black Hills every year.

JimboFunFinder · 06-05-2019, 03:17 PM

I ordered a Valtera 3" gate valve (identical to the FF one) and replaced it. The hardest part was getting at the bolt which was very close to the holding tank. The other three were relatively easy. Since my FF model has the belly pan I had to remove the foamed insulation and then cut the pan so I had enough space for working. I used weather stripping adhesive to secure the two gaskets to the gate valve while I inserted it. Now I need to close up the opening in the belly pan with foam insulation and the special tape (I found everything on Amazon). I sure hope this valve blocks the sewage from leaking into the drain line! It took time and smelled nasty but I figure I saved a couple hundred dollars and the time to take it to a RV shop.

profdant139 · 06-05-2019, 07:09 PM

Well done! I hope the leak is fixed.

JimboFunFinder · 06-07-2019, 02:53 PM

This final photo shows Humpty Dumpty back together again. I used 4 inch wide Flex Mend Premium Bottomboard Tape (which looked to be the same tape used by FF at the factory) and Great Stuff Multipurpose Black Insulating Foam Sealant so hopefully the mice will stay on the outside. I was apprehensive about using the foam after reading the dire warnings on the can but it all went smoothly.