I hooked up the Flush King to clean out our black water tank, turned on the garden hose, then started doing something else. This was a big mistake! I forgot about filling the black water tank! I ran down to the camper and turned off the water, but too late, the damage was done. But I am a little puzzled about what happened.I found the black water tank laying on the ground under the camper. It had separated from the toilet flange fitting and broke the metal holding straps. However, there was no liquid INSIDE the camper. Apparently the toilet valve held. The black water tank has two openings in its top: one larger for the toilet and one smaller for the vent line. I do not understand why no water escaped though the vent, unless it was plugged. I'll be checking it out this weekend when I have time to work on it.Both openings in the tank have/had rubber grommets into which the ABS plastic pipe fit. Black ABS cement was used to seal these fittings.No fittings were damaged, so I will reassemble everything and replace the straps. Questions: How should I prepare the plastic pipe and rubber grommet for the cement? Does the cement require any kind of activator / primer to be applied to the fittings?Thanks.

I think an important question is why did the straps fail. Are they going to fail again the next time the tank becomes full?

Make sure to use stronger straps or double them up. You'd think they would be designed to hold up to twice the weight of the tank filled to capacity.

I'm not certain about the root cause of the strap failure. Was it the weight of the water or was it the weight plus the water pressure that built up combined that caused the failure? If I find a blockage in the vent then I'd say the latter.

The rubber grommets normally do not use any adhesive. They normally have grease to insert the pipe and then it is friction tight to prevent leaks.When the tank bulged from excess water the straps failed. Use something better then strapping. I have seen U-strut used and angle iron.

enblethen wrote:The rubber grommets normally do not use any adhesive. They normally have grease to insert the pipe and then it is friction tight to prevent leaks.When the tank bulged from excess water the straps failed. Use something better then strapping. I have seen U-strut used and angle iron.X2, I would also use bolts and nylock nuts to hold the channel or uni-strut in place instead of screws. JMO

Blew Out Black Water Tank Jayco 23B | Good Sam Community

RCMAN46
Explorer
Nov 06, 2015
I suspect some toilet paper floated and that is what plugged the vent.

The reason I believe the staps failed the tank blew up like a ballon. If you look there are very large flat areas on the bottom and top of the tank with very little if any support.

I would be concerned it the seams where the upper and lower sections of the tank are connected have been compromised.
BigSkyTrailer_G
Explorer
Nov 06, 2015
If nothing else, this thread will have me checking my Black water tank straps pretty soon!
LEMII
Explorer
Oct 27, 2015
Yes, mine were loose, but I molded them around the edges to achieve a much tighter fit. Still, I think the brackets are the main support and the straps are probably meant to be a back-up.
RinconVTR
Explorer
Oct 26, 2015
This thread has me rethinking what those tank straps are really for.

I thought they were safety straps, in case the tank somehow comes off its lip, a top the frame while driving.

But here, many are implying they should help hold the tank. What concerns me about this, is every strap on each tank on my camper...are loose. I can fit my hand in between the straps and the tanks.
LEMII
Explorer
Oct 26, 2015
Well, the repair is complete. I verified that the vent was clear, so it had to have been the weight of the water that caused the tank to drop. I did notice softness in the underside of the floor around some of the support brackets. I had to reposition a few to screw into solid wood. I found the metal straps from a local mobile home supply company. and replaced the two thinner straps with a total of four thicker straps, two of which I attached to the metal frame of the camper. While down there, I replaced the black water gate valve.

Guess I'll have to wait until next season to test it our properly, but it seemed to turn out pretty well.
hohenwald48
Explorer
Oct 20, 2015
And that's why every black tank flusher I ever saw says to leave the black tank valve OPEN while using the flusher.
LEMII
Explorer
Oct 08, 2015
enblethen wrote:
Mobile home supply. Straps are used to secure them to foundation.

Great idea!

Thanks.
enblethen
Nomad
Oct 08, 2015
Mobile home supply. Straps are used to secure them to foundation.
Lynnmor
Explorer
Oct 08, 2015
LEMII wrote:

Any ideas as to where I could find galvanized metal straps of the right gauge, width, and length?

Find a sheet metal fabricator in your area and have it made to your specifications. You should be able to have this done at a reasonable cost. Much of the perforated strapping at hardware stores is not very strong.
BTPO1
Explorer
Oct 08, 2015
LEMII wrote:

Any ideas as to where I could find galvanized metal straps of the right gauge, width, and length?

Home Depot, Lowe's, Ace/True Value they should all have what you are looking for.