Black Tank Flush Lesson Learned

BBBlue · 10-07-2017, 07:05 AM

After having issues with both gray water tanks, one requiring replacement the other repair, I felt pretty lucky that the black water tank has made it this long without a leak failure until my last outing.

I got into a habit of filling the black water tank after dumping with the tank installed flush and dump valve closed. I would fill it up completely and then dump completely and repeat another time. This, I felt, would leave me with a pristine clean tank. I have done this since owning our 2013 Sanibel 3500 new.

On the last outing I was going through my black water tank cleaning ritual and during the last fill (with dump valve closed) was distracted and had a senior moment forgetting about the tank until hearing a loud "boom" inside the unit. My wife and I went outside to see what the noise was when I remember I was filling the black water tank. I immediately turned off the water and dumped the overfilled tank. Did not see any water coming out of the bottom of the trailer, so I started to pull off an area of the underbelly covering and seen a little water. We had a couple days of camping and decided not to use the tank until after we returned home and I could accomplish a complete inspection. Got home, pulled off a good section of underbelly where I could get a good look. I discovered that the tank came off of one the side rails and dropped about 1.5" before jamming up against the rail. I was able to support the tank and loosen the side support rail, jack up the tank and reinstall the rail. Slowly filled the tank and had a slow leak at the dump valve flange gasket. No other leaks. Luck me!!

Lesson learned: Don't use the blackwater flush with the dump valve closed in an attempt to get the tank pristine. At least for this camper. I lucked out, for if the black water tank would of had to be pulled, the gray water tank below it would of had to be pulled to. Would of been costly and time consuming.

RSchleder · 10-07-2017, 07:28 AM

When back flushing my black water tank I will close the valve for a minute or two then open the valve back up to drain out the accumulated water. I do this while kneeling at the valve and perform this task 2-3 times during a rinse. Works for me and it's very difficult ( though I agree not impossible) to have any senior moments while kneeling at the valve!

BGKirkham · 10-07-2017, 07:43 AM

Quote:

Originally Posted by BBBlue

Lesson learned: Don't use the blackwater flush with the dump valve closed in an attempt to get the tank pristine.

The lesson I took away from your story was to not get distracted while flushing a tank. YMMV

**Mr. Dan** · 10-07-2017, 08:26 AM

Once while I was in the midst of this process, a couple of ol' boys walked up on me and asked me about my Andersen Ultimate hitch. Of course, I was giving them the complete sales pitch when I heard "DAN!!!!"

I knew immediately what had happened. As I ran to open the black tank valve, I shouted over my shoulder to the ol' boys "This is on you!" Fortunately, we only had about a gallon of water come out the toilet. Didn't take long to clean up. Changed my mental process while dumping!

clintbonnie73 · 10-07-2017, 12:26 PM

Sounds to me like the tank coming loose might have happened during a normal full tank of black water. Good that you re-supported it better.. Good to know info..

rracer5 · 10-07-2017, 12:45 PM

Quote:

Originally Posted by Mr. Dan

Once while I was in the midst of this process, a couple of ol' boys walked up on me and asked me about my Andersen Ultimate hitch. Of course, I was giving them the complete sales pitch when I heard "DAN!!!!"

I knew immediately what had happened. As I ran to open the black tank valve, I shouted over my shoulder to the ol' boys "This is on you!" Fortunately, we only had about a gallon of water come out the toilet. Didn't take long to clean up. Changed my mental process while dumping!

And I'll bet they were no where in sight when you went to see if they were still around!!

rracer5 · 10-07-2017, 12:47 PM

Quote:

Originally Posted by RSchleder

When back flushing my black water tank I will close the valve for a minute or two then open the valve back up to drain out the accumulated water. I do this while kneeling at the valve and perform this task 2-3 times during a rinse. Works for me and it's very difficult ( though I agree not impossible) to have any senior moments while kneeling at the valve!

X2 I never leave the side of the RV when draining/flushing tanks.

JimMorrell · 10-07-2017, 12:50 PM

I use the wash out feature to add water to the black water tank, but I stand near and count or watch my watch till I get to 2 minutes. At a rate of 3 to 5 gallons per minute filling, I now have between 6 and 10 gallons of water in the tank. At this time, I turn off the water. NEVER walk off and leave it run !

Boots49 · 10-07-2017, 01:24 PM

I found if you do a black tank rinse, most people open the water & let it run until the water runs clean. All you are doing is pushing the stuff to the side of the tank & you have clear water running out, tank looks clean but actually isn't.

This is what you should do to actually CLEAN the BLACK tank. After your tank is drained, turn your rinse on & let it run for 20 seconds or when the clear water starts to come out, shut the water off & you will see more crap coming out of the tank. Now turn on the rinse again & repeat the wash out.

I did this 4 or 5 times & quit, because the stuff was still coming out, but after 6 or 7 trips I found the water running clear after only 2 rinse

. A fellow RV-er sugestted after draining your tanks and you're ready to travel, add a bowl of water with a good shot of Dawn dish soap to the toilet and and each grey tank. If you use the toilet while traveling from A to B, this is OK. When you arrive at B dump your tanks right away. You do not have to fill up the tanks to 2/3 because you have not used the tanks that much, now rinse once more close the gates & add water to your tanks. I do this for all 3 tanks.

This process has totally eliminated the use of all chemicals in my holding tanks with the exception of Blue Streak for the toilet. If you don't use this then you have to use whatever you are used to in the toilet.

Good luck dumping!

babock · 10-07-2017, 01:33 PM

Quote:

Originally Posted by BGKirkham

The lesson I took away from your story was to not get distracted while flushing a tank. YMMV

Me too.

It's good you posted though.

Sealyn · 10-07-2017, 04:20 PM

Use a kitchen timer and keep it with you when filling the black tank, even if distracted you will get a reminder.

elchilero53 · 10-07-2017, 04:54 PM

I use the pulse flush technique as well (drain black water, then gray water then tank flush on for a minute, off until drained, on again etc.) but haven't had any desire to turn the flush on while the valve is closed. I've heard of the Dawn Dishwashing trick. Several have suggested using a bag of loose ice in the BW tank as well until I get to my destination (supposed to scrub the tank and clean the sensors) but I haven't tried it yet.

palmetto rogue · 10-07-2017, 04:54 PM

Here is a similar lesson on my 2013 Silverback. I hooked up the park water to the rig and did not notice that the fill valve was set to fill the tank instead of to the house. Well about 20 mins later the floor of the trailer had a bulge and out I ran to shut off the water.
I use a 30 psi regulator but Forest River in its typical absence of wisdom plumbs the overflow using 1/2" pex elbow which has a 5/16" id. With 1/2" pex inlet there is no way the overflow can actually function as an adequate overflow without pressurizing the tank. As with your black water tank, I pulled the bottom panels off and the cross supports and strap brackets were bent and the tank hanging. The crushed heating duct amazingly returned to original shape and no other damage. Spent the day fixing this and replumbed with 1/2" npt to 3/4 pex fitting which has a 5/8" id and used larger hose for the overflow. Now I have 5/16" inlet and 5/8" overflow which should deal with my next brain fart.

Other situations have caused me to believe this is typical of everthing done in Forest River RVs. Everything seems to be designed to be just at the point of failure and waiting for the simplest of mistakes or stresses. I think FR thinks RV stands for Repair Vehicle. It was my mistake but proper plumbing should not have allowed this to happen in my case.

**Mr. Dan** · 10-07-2017, 05:12 PM

Quote:

Originally Posted by rracer5

And I'll bet they were no where in sight when you went to see if they were still around!!

Right!
Which ol' boys?

Comanchecreek · 10-08-2017, 09:33 AM

I've never really had much luck using the rinse out fitting on my black tank. Always seems to be stuff left after it's use. I throw a hose down the toilet and let it rip. I pull the valve when it's about half full. Will take four or more times to get clear water every time.

Filterman · 10-08-2017, 04:35 PM

Quote:

Originally Posted by RSchleder

When back flushing my black water tank I will close the valve for a minute or two then open the valve back up to drain out the accumulated water. I do this while kneeling at the valve and perform this task 2-3 times during a rinse. Works for me and it's very difficult ( though I agree not impossible) to have any senior moments while kneeling at the valve!

X2 Exactly

jojoshort · 10-08-2017, 04:56 PM

We, also, shut the black tank valve while running some water into the black tank with the black tank rinse. After getting home, I found the toilet paper roll, sitting beside the toilet, was damp. The first time we thought we had water perhaps dripping from the vent overhead. Then it happened again, when we had just dumped and opened and closed the black tank valve. Now the bathroom had an off odor of urine...ugh. I figured what must be happening during the dump is that when we closed the tank valve with the flush running and then quickly pulled the tank valve, some fluids must've "burped" back up into the toilet. The toilet is a two-piece, and the place where they fit together had some fluid in it. We've cleaned it up with urine clean and deodorized and sanitized, but never, ever again will we leave the black tank valve closed while running the rinse.

Philkaty · 10-09-2017, 08:17 AM

We went out for the first time this weekend and the black tank didn't say it had anything in it according to the LED's. When I opened the valve it all came out as normal. hooked up the hose to the flush and closed the valve and then opened it. clean water came out. not sure about the sensors. Question: do you need to put a regulator on the flush hose?

rracer5 · 10-09-2017, 11:54 AM

Quote:

Originally Posted by Philkaty

We went out for the first time this weekend and the black tank didn't say it had anything in it according to the LED's. When I opened the valve it all came out as normal. hooked up the hose to the flush and closed the valve and then opened it. clean water came out. not sure about the sensors. Question: do you need to put a regulator on the flush hose?

Don't believe your sensors....especially the black tank. They get "debris" on them which will show erroneous readings.

If the campground has high water pressure, it's better to use a regulator there too. Less chance of blowing plumbing apart not the mention damaging the anti-siphon valve that should be on your black tank flush plumbing.

Philkaty · 10-09-2017, 12:32 PM

this is the first time taking it out. the gray tank worked fine. will try to mess with it this weekend. thanks

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