Thread Tools Display Modes
Old 02-08-2016, 08:35 PM   #1
Senior Member
Join Date: Mar 2013
Location: Minnesota
Posts: 214
Black water tank flush system leak

I am on the road in Florida and when I tried using the flush I got water leaking under the sink of our W and it ran across the floor and out the front of the slide as it was tilted that way. Tested today and I see it is a simple system with some type of valve at the high point. This is where it is leaking. Anyone else have this issue? Repair or replacement issue?

2016 Sunseeker MBS W
2010 Honda CRV- SMI Stay In Play Duo
Previous-5th wheel, Class C, tent trailer, tent
SSmbs is offline   Reply With Quote
Old 02-08-2016, 10:26 PM   #2
Senior Member
MNtraveler's Avatar
Join Date: Oct 2015
Posts: 1,265
Not sure on that but are you using a water pressure regulator to be sure you are not overpressurizing the line, as you may hit a pressure relief valve. Otherwise it might be plugged on the inside causing a back-flow condition in the water line. Just some speculation on my part to give you a couple of things to start on.

PS: this should probably go in the tech plumbing forum since it's not about the MBS chassis. You may get more answers there.

2016 Forester 2401R
MNtraveler is offline   Reply With Quote
Old 02-09-2016, 05:04 AM   #3
Phat Phrog Stunt Team
AquaMan's Avatar
Join Date: Apr 2012
Location: Ohio
Posts: 5,937
Your anti siphon valve has sprung a leak. You can (and should) replace with either a stock unit or a a unit from Home Depot or Lowes. The latter will most likely require some additional plumbing.

Sent from my iPhone using Forest River Forums
2016 Georgetown 364TS
Nights Camped
2014 - 56
2015 - 41
2016 - 64
AquaMan is offline   Reply With Quote
Old 02-09-2016, 06:06 AM   #4
Senior Member
Join Date: Jul 2010
Location: Waynesville
Posts: 9,560
Replace This,with a better one from H/D! Run a Search at Top Plenty of Info! Youroo!!
Attached Thumbnails
Click image for larger version

Name:	DSCF2200.jpg
Views:	101
Size:	258.1 KB
ID:	99241  
youroo is offline   Reply With Quote
Old 02-09-2016, 06:17 AM   #5
Senior Member
nomad297's Avatar
Join Date: Jul 2015
Posts: 1,192
With no pressure in the line, give the valve a whack with the handle of a screwdriver. This may fix it.

2016 Rockwood Windjammer 3029W Diamond
2015 Chevy 3500HD LTZ 6.0 Crew Cab 4x4 Long Bed 4.10:1 SRW
nomad297 is online now   Reply With Quote
Old 02-09-2016, 08:42 AM   #6
Senior Member
Join Date: Mar 2014
Posts: 1,607
X2. Just curious, sometimes they act up when you either over pressurize or tanks are near full. Just a hunch.
Still Kickin is offline   Reply With Quote
Old 02-09-2016, 03:16 PM   #7
Senior Member
Join Date: Mar 2013
Location: Minnesota
Posts: 214
Probably overpressurized. Happened at a RV park with high water pressure. Looks like it is a JR brand one. $38 online. Still on warranty so I will look for a Forest River dealer. Looks like a 5 minute replacement with no tools needed.
2016 Sunseeker MBS W
2010 Honda CRV- SMI Stay In Play Duo
Previous-5th wheel, Class C, tent trailer, tent
SSmbs is offline   Reply With Quote
Old 02-09-2016, 04:13 PM   #8
Usually Confused Member
emm-dee's Avatar
Join Date: Nov 2015
Location: Georgia
Posts: 926
The valve shown in YooRoo post #4 is notorious for failure. Sometimes it's the valve but more often it's the clamping on the hose. Run some water and look to see where the leak is occurring. If it coming out from the hose connection at the clamp, replace that with a more robust clamp that can be tightened with a small socket.

If it's coming out the top of the valve you'll probably need a new one. I replaced mine with the Watts LF7 ( LF7 Lead Free* Bronze Dual Check Valves, Dual Checks / Dual Checks with Atmospheric Vent, Backflow Prevention - Watts ), All brass. You'll have to search the HD or Lowes bins to find the correct fittings to attached it to the existing hoses but when installed all the problems go away.

Another option a neighbor used is a Valtera clear plastic valve that allows you to see everything inside. It's an easier fit than the Watts but I don't know about its reliability, etc. (neighbor hasn't had any problems).

Check Valve/Vacuum Breaker, 1/2″ MPT, Bulk - |

At some point during every day you suddenly realize nothing else productive is going to happen the rest of that day. For me, it usually occurs around 9 am.

Vengeance 25V (the Harley needed a home)
emm-dee is offline   Reply With Quote

black, black water, leak, tank, water, water tank

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

» Virginia Campgrounds

Reviews provided by is not in any way associated with Forest River, Inc. or its associated RV manufacturing divisions.

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities

Copyright 2002-2015 Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 04:08 PM.