What’s the drain coming out of my trailer

[mslater741]

There is a piece of blue tubing coming out of my RV just behind the axles that drains water from time to time ....it has a shut off valve on it .... what’s it for ?

 

[hoefler]

Most likely fresh water tank over flow

 

[jnbhobe]

Fresh water tank drain.

 

[sengli]

on most rigs there are two of these, one exiting on on either side. Mine came with just a 90 degree elbow on them from the factory, so yours has a valve?

 

[cookie]

What rig do you have? I'm going with Jon, the fresh water tank drain.

Peace
Dave

 

[JWalker]

We have 3 lines running out the bottom of the trailer. 1 blue and 1 red, with shut off valves. These are our low point water drains. We also have a blue line exiting near the axles. This is for the freshwater tank.

 

[JohnDar]

Water tank drain. Mine looks like this and I don't have any overflow lines sticking out of the belly, just the drain and the two low point drains on the curb side.

 

[Lynn1130]

OK, I am going to do this again because I got confused (what else is new).

We probably need to know what trailer because the fresh tank drain is located in various locations on different trailers.

Mine is on the ODS just to the rear of the water heater and has a valve to control the drain. The overflow drains, of which there are three on my trailer did not come with valves but I put valves on the to keep from slopping water out when traveling. Two are just in front of the axles one on the ODS and one one the door side. The other is just behind the tank drain near the water heater. Since the OP's has a valve it probably is the tank drain but the type of trailer would help pin it down instead of all of us continuing to guess.

 

[MTPockets]

Our BigHorn had a drain with a valve; the drain is used when you want to drain/empty the fresh water tank. There is also an overflow tube that allows water to flow out when the tank is full. I think if you close off the overflow and continue filling when full, water pressure could burst your tank.

 

[Lynn1130]

water pressure could burst your tank.

And it will. Which then causes all kinds of leaks and problems. Always open the drain valves when filling.

 

[JohnD]

And it will. Which then causes all kinds of leaks and problems. Always open the drain valves when filling.

Don't open the drain valves...but open the overflow (drain) valves if you have put valves on them.

It really is not a good idea to close off the overflow drains.

As for the tank drains by the axles...this is what they look like (blue pipe):

 

[JohnDar]

The one modification I've done to the tank drain is to secure a short piece of Tygon tubing to it with a male hose fitting on the end. That way I can divert the water out from under the rig and into an open area when I need to drain it. During normal use, we're on city water, but I keep 20 - 30 gallons of water in the tank for those occasions when the CG power fails and their pumps shut down in the middle of a storm. That way I can still flush the commode using battery power and the water pump. Happy wife...happy life.

 

[mslater741]

OK, I am going to do this again because I got confused (what else is new).

We probably need to know what trailer because the fresh tank drain is located in various locations on different trailers.

Mine is on the ODS just to the rear of the water heater and has a valve to control the drain. The overflow drains, of which there are three on my trailer did not come with valves but I put valves on the to keep from slopping water out when traveling. Two are just in front of the axles one on the ODS and one one the door side. The other is just behind the tank drain near the water heater. Since the OP's has a valve it probably is the tank drain but the type of trailer would help pin it down instead of all of us continuing to guess.

2014 big horn 3585

 

[JohnDar]

Probably pretty simple. If it’s blue and has a valve, it’s a fresh water tank drain. No valve, it’s probably a fresh water tank overflow line. A blue & red line together, with valves, and you’ve got yourself some low point drains. 5-4-3-2-1 launch rocket


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[Lynn1130]

It really is not a good idea to close off the overflow drains.

Perhaps but if you dry camp and would like to arrive at your camping site with a full load of water you best put a valve on them. Otherwise, and there are several here who have asked where there water went when the got to camp, you will have a half a tank when you arrive. Trust me, I know from experience.

One item on my check list for setup is to open the overflows. This provides equalization for the system and makes sure they are open when I fill the next time.

 

[JohnDar]

If you fill it via that wonderful Anderson valve I’ve read about, I suppose it would be possible to pressurize the tank or overfill it. With the old-timey gravity fill port, when the tank is full the excess comes back at you.

With opening/closing your overflow valves as part of you preflight checklist, you have it covered for you manner if usage. The way we use ours, the tank is always empty when the rig is moved.


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[mlpeloquin]

If you added valves to the fresh water tank overflow lines, only close the overflow valves when traveling in order to keep all the water in the tank. Open them as soon as you pull into camp. If hooked up to the camps fresh water supply along with a failure of the Anderson valve, and then the failure proceeds to fill the fresh water tank, it would not be a good experience.

 

[Lynn1130]

With the old-timey gravity fill port, when the tank is full the excess comes back at you.

Not always. If you put the hose nozzle in and let it go you can blow the cross hose off of that is between the tanks, causing a major leak. You then have to drop the covering and the supports to repair it. I found out the hard way.

If you added valves to the fresh water tank overflow lines, only close the overflow valves when traveling in order to keep all the water in the tank. Open them as soon as you pull into camp

My point in my previous thread. Close them when you travel. That stops water loss. Open then when you arrive.

 

[JohnDar]

Not always. If you put the hose nozzle in and let it go you can blow the cross hose off of that is between the tanks, causing a major leak. You then have to drop the covering and the supports to repair it. I found out the hard way.



My point in my previous thread. Close them when you travel. That stops water loss. Open then when you arrive.

The "cross hose" must be unique to certain models. Mine is a single fresh water tank. Even with a length of hose stuffed in, it still comes out the fill port. But, I have a water meter in the system so I can tell how much water has gone in. It only gets filled twice in the spring; first to sanitize it and the second to rinse it out. Then I add my 1/2 tank of "emergency" water that gets drained in the fall when we're putting the rig away.

Supposedly, my rig can hold 75 gallons of fresh water. 12 gallons of that is the water heater, leaving 63 gallons. At about 60, I get backfeed out the gravity port, so I stop at about 55 gallons. Part of the key is learning, hopefully not the hard way, what you can and can't do with your rig.

 

[Lynn1130]

I now have a water meter to help determine where in the fill process I am. I have two 50 gal tanks connected to make 100. With tanks, water heater and water lines I am 114 gals full. I think most of the "100" gallon trailers are actually 2 50 gal tanks connected.

I never leave water in the tanks. In Phoenix it will be so full of algae that it might not even drain. Sitting water in this country grows some pretty ugly stuff.