Thread Tools Display Modes
Old 06-25-2012, 01:10 AM   #1
Junior Member
Join Date: May 2012
Posts: 5
Filling fresh water tanks, overflow

I've got a new 2013 305V12, all of 6 weeks now (been out 4 of those weekends) and I'm starting to have a few problems with the unit. If I fill the fresh water tanks near max then it starts draining out the overflow. Problem is that it doesn't stop draining until I am down to 1/3 fresh water. Is there a vacumn issue or away to resolve this?

sberard is offline   Reply With Quote
Old 06-25-2012, 02:27 AM   #2
Senior Member
2Susan's Avatar
Join Date: Jun 2010
Location: Southern Alberta
Posts: 459
It is siphoning out. Clamping the overflow tube stops the siphon. Unplug the tube before using water so air can enter as water is used.

2Susan is offline   Reply With Quote
Old 06-25-2012, 06:12 AM   #3
Site Team - Lou
Herk7769's Avatar
Join Date: Oct 2009
Location: South Eastern PA
Posts: 21,379
This problem can be caused by a poorly routed and/or overly long vent hose.

Not an easy fix, so the "plug or clamp the vent hose" trick might work for you.

If you want to fix this permanently, Here are some suggestions and photos of the area (not all of my camper).

My vent hose goes pretty much straight up from my tank; Through the compartment behind my WFCO power center; and up to the fill port right under the fridge inlet vent.

Even though pretty straight, it still manges to push water out the vent long before the tank is full because when connected to the TV (like at a water fill station) the tank is rotated down towards the fill, vent, and water pump hoses.

When hooked up, about 3/4 tank, the vent hose is under water. This pushes water out the vent and, because the hose pressure can put water in faster than the vent can relieve it, the tank bulges and burps the water out the fill port when you remove the hose.

The tank must be exactly level (or in my case even tilted slightly to the rear of the camper) to get a 100% fill.

Wind blowing past the open screened end of the tube, causes a low pressure to develop at the vent hose inlet. The Venturi Effect acts on the hose end sucking the water out. A loop in the hose makes the pressure required to start the siphon lower (the water is closer to the open end and easier to get the siphon going) and campers with a looped vent hose see this effect a lot more often than those with a straight hose.

Driving down the road; normal sloshing of the tank and the Venturi Effect of the wind, will pull and slosh water out the vent line starting the siphon.

The Fix:

1) Drop the belly panel and make sure the hose has no low spot where water can pool so air can escape the tank. (As straight UP as humanly possible.)

2) Install a door (locking) on your fill port. This serves as dual function of limiting the Venturi effect and securing your fill port to casual vandals.
Attached Thumbnails
Click image for larger version

Name:	Horst Probe Install 020.jpg
Views:	324
Size:	59.6 KB
ID:	15688   Click image for larger version

Name:	photo(7).jpg
Views:	193
Size:	31.9 KB
ID:	15689   Click image for larger version

Name:	Water%20Tank%201.jpg
Views:	481
Size:	43.4 KB
ID:	15691  
Attached Images

Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
Herk7769 is offline   Reply With Quote
Old 06-25-2012, 08:29 AM   #4
Senior Member
tomjsas's Avatar
Join Date: Aug 2009
Location: Northern Colorado
Posts: 508
I've had simlar issues with my 2501ss. Would be driving down the road and see water dripping out from the overflow. I just put a small piece of duct tape over the overflow vent/screen by the water fill and don't have the issue. I remove it once I'm at the campground to allow the tank to breathe when pumping. The tape is easy to take off and replace each time.
Pull-Rite 16K Super 5th
2014 Rockwood Signature Ultra-Lite 8289WS
2011 Chevy 2500HD - DuraMax (Just over 5000 miles now!)
Nights camped in 2014 - 21
tomjsas is offline   Reply With Quote

led pad

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

» Featured Campgrounds

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

Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 07:58 PM.