Friday, June 2, 2023


What are these tubes for?


gary-736Dear Gary,
The attached photo shows two tubes sticking down from the enclosed bottom of our ’06 travel trailer near the black and gray holding tanks. Do you know what they are for? Thanks. —Jack

Dear Jack,
Those two tubes are the low point drains for both the hot and cold water lines in the fresh water distribution system. The code for RV construction mandates each side of the fresh tubing (hot and cold) must have valves, plugs or caps, at the purported lowest point in the system for ease of emptying the system for winterizing purposes.

In your case, you have simple caps that can be removed to empty the hot and cold lines in the trailer. It’s also handy for flushing out and chlorinating the fresh water system. They are not relative to the holding tanks, their proximity notwithstanding.

Read more from Gary Bunzer at the See Gary’s videos about RV repair and maintenance.




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Bob Shaw
6 years ago

Great info – I have managed to ‘misplace’ my 2 caps for the drain hoses on my 2001 Elkhorn Truck Camper – What size are they and where can I get replacements?? Thanx

Bob Shaw
6 years ago
Reply to  Bob Shaw

I bit the bullet and got the truck out of storage and drove to an RV parts store and bought the ones I needed – Typically, one size fits all, does not fit here –

6 years ago

I’ll ask a follow-up to this, since I have a weirder similar question. Read carefully since your low drain answer won’t fit. My rig has two sets of open ended tubes, one pair at the rear and one next to the fresh tank drain. Both are labelled as “low point drains” by stickers, and the rear pair actually are (valving located inside to drain plumbing). The mid-pair however has no accessible valves anywhere. I thought it must be a second set for a second belly point, where factory forgot an access to buried valves. Not so, since I can see all my pressurized water lines in the area, and the tubes don’t hold air pressure injected from outside. Now I thought just a mistake, and they don’t connect to anything. Not so once more – if you overfill the fresh tank, water will spray out of both tubes. They apparently act as double vents to the fresh tank (already vented by the normal fill cap), only point downward to collect road dirt and allow bugs unscreened access into the fresh tank? What the heck is the intention here?

6 years ago
Reply to  Wolfe

My trailer has two “vent” pipes sticking down near the fresh water tank. One is the vent and the other the overflow. Of course the vent also will have water coming out when you overfill the tank. SO I am not really sure why both are needed.

Unlike your rig I do have have a gravity fill. The fresh water tank is filled using the city water inlet so there is no vent at the fill.

6 years ago
Reply to  Nathan

Having that overflow vent makes sense for a pressurized full as you have, so I guess it’s just a screwup at the factory putting both tubes and gravity fill on my rig. Ironically, since buying this unit, i’ve added my own DIY hot water reclaimer/ city-to-tank filler, so it mught be less alarming to neighbors if i overflow under the rig instead of out the hose-fill…lol. Thanks for info.

Brian Jensen
6 years ago

After hearing about the mess “love bugs” make on RVs I decided to put PEX hose end connections on my low point drains. Now I can hook up a hose to either the hot or cold water in case of a gooey emergency.

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