Winterization of Fresh Water Tank

[eagleof72]

I drained the fresh water tank on my 2004 Rockwood Roo as much as I could get out after winterizing the rest by pumping in antifreeze via the bypass. I also lowered the tongue way down to move all the water in the fresh tank toward the open drain. There may be a small amount of water in the bottom as the drain is on the side at the bottom, not out of the bottom. My question is should I dump some antifreeze in the maybe 1/8" of water? Most say the taste will linger.

Thanks,
Brett Sprout
Ohio
2004 23B Rockwood Roo
2012 Ford F150 4X4

[Mr. Dan]

I don't put any antifreeze in my fresh water tank with the theory (at least) that there's so much room for ice to expand, nothing would be split/busted/ruined, etc.

[mjones12]

Originally Posted by Mr. Dan

I don't put any antifreeze in my fresh water tank with the theory (at least) that there's so much room for ice to expand, nothing would be split/busted/ruined, etc.

Exactly. Probably a little water left in your drained water heater, too. Nothing to worry about.

[Brucecav]

Well I blow my water out and empty the fresh water tank but did have the drain valve crack once so I add a small amount of antifreeze to the fresh water tank and open the valve to let a little antifreeze in it.

Every spring I then drain the small amount of antifreeze out of the tank add 1/2 cup of Clorox and fill the fresh water tank. I then run the chlorinated water through all the pipes let it sit over night then drain and fill fresh water tank again and run water through the pipes again and drain again.

Should kill any bacteria in the water pipes and fresh water tank.

[Comanchecreek]

Why risk a cracked tank. It does happen. Same for your holding tanks. Pour some pink stuff in and forget it. Takes an extra 15 minutes to flush in the spring. Fill full, drain, do it again. You can also use your water pump with the low level drains open to drain it faster. I do it every year and never have left over pink when fully flushed.

[clintbonnie73]

Originally Posted by Comanchecreek

Why risk a cracked tank. It does happen. Same for your holding tanks. Pour some pink stuff in and forget it. Takes an extra 15 minutes to flush in the spring. Fill full, drain, do it again. You can also use your water pump with the low level drains open to drain it faster. I do it every year and never have left over pink when fully flushed.

I completely agree... !

[satdog01]

Would it be a good idea to run pump to get pink stuff in line from tank through pump? I ask as there a god ten feet of tubing from tank to pump on my Flagstaff. Not sure low point drain gets this line.

[NMWildcat]

I would never put antifreeze in the fresh tank. Takes forever to get it out. I drain mine, run the pump dry. Leave the fresh drain and vent open. Never had a problem in any climate.

[CoMaddMax]

"Never had a problem in any climate." Hi NMWildcat I see you live in southern NM and I see the original post lives in Ohio where they have sub zero temps.... How cold does it get in southern NM?

[Flybob]

I do not recommend adding pink stuff to the FW tank. It is too hard to get all the pink stuff out in the spring. Leave the drain slightly open. The little bit of water in the bottom of the tank is no problem even if frozen as it will not damage he tank. The damage from ice comes from the fact that it expands when it freezes and if there is no room for expansion, it will crack something. As for the line from the FW tank to the pump it is usually reinforced vinyl hose that can handle freezing. In addition, most of the water in that line drains back into the tank when you open the winterizing valve on the pump input.

[jimmoore13]

The right answer is conditioned on your particular tank and RV configuration.

Most molded tanks are somewhat rounded at the corners...at least on the inside. The molds are not sharp-cornered, because it makes removing the tank from the mold difficult. With that in mind, ice needs "purchase" on the tank body to crack it. With a rounded corner, the ice will begin pushing, but the rounded corner will force the ice upwards--like a ramp--and the ice will not generate enough force to crack the tank. This is the same principle that protects the interior of your hot water heater tank from residual water in the bottom cracking the hot water heater tank.

Tanks are also frequently made from SLIGHTLY flexible material. Valves, on the other hand, are another matter. A valve on the side of the tank is a tiny, captive space, and it's not flexible in the least. Ice inside a valve will crack it easily.

If you don't want to deal with RV antifreeze in your tank, in your particular case, you have two options.

1. You say you tilted the tongue of the trailer down as much as possible to facilitate draining. The good news is that when you raise the tongue, it will move residual water away from the drain valve.
2. Fabricate adapters to enable you to use air to blow out the drain valve and the fitting for the water pickup to the pump. With the pump pickup, you install a second RV antifreeze pickup oriented in the opposite direction...enabling you to push air through the hose and into the tank. With the drain, you might just adapt your blow gun to fit over the drain petcock with a wine cork or similar. Take the cap off the fill port for an extra measure of safety to prevent pressurizing the fresh-water holding tank.

That's a bit of work...perhaps comparable to sanitizing after using RV antifreeze as others suggest. But it's an option.

Personally, my HW-277 is configured such that I just open the drain petcock and leave it open. I turn on the water pump and open the low-point drains and let it pump itself "dry"...it gurgles and sputters and spits, but it's never quite dry---but dry enough so that the supply line to the pump is drained, the pump input is not filled with water, and it has pushed water away from the output side of the pump.

I then winterize all of the freshwater system with an air compressor...run the pump again, just to be sure, and I have had no freeze problems (in the mountains of Colorado) for four winters. But I emphasize that every RV design is different, and my simple little PUP is not representative of more complex designs. A belly in a PEX line or a tilt to a holding tank can defeat virtually any air compressor. And...the air compressor does not push air through the pump. There's a check valve down-stream of the pump that prevents city water from back-feeding the fresh tank, and air-winterizing relies on the city water supply connection.

I adopted this air-winterizing tactic, because my wife is very sensitive to the taste of chlorine. When I sanitized our newest camper after taking delivery, she could taste chlorine well into July. This is complicated by the fact that we are on a well, and there is no chlorine in our household water.

P.S. I use RV antifreeze in the black tank and gray tank...and the drain traps. The antifreeze protects the traps (one of which hangs below my floor) and the dump valves. The black and gray tanks all have large radius rounded corners, so once drained, there's no risk of residual ice cracking the tanks, but the RV antifreeze also protects against "solids" drying and hardening on the tanks' floors.

[A32Deuce]

Originally Posted by CoMaddMax

"Never had a problem in any climate." Hi NMWildcat I see you live in southern NM and I see the original post lives in Ohio where they have sub zero temps.... How cold does it get in southern NM?

I'm in Jersey and never add antifreeze to the fresh tank and no problems in 5 years with this unit. It does get below 0 here!

[doc73]

Originally Posted by A32Deuce

I'm in Jersey and never add antifreeze to the fresh tank and no problems in 5 years with this unit. It does get below 0 here!

Same here in PA.. Since 06 only blow the lines out and drain the tank. No pink stuff in the fresh tank.

[KFX450RXC]

Originally Posted by NMWildcat

I would never put antifreeze in the fresh tank. Takes forever to get it out. I drain mine, run the pump dry. Leave the fresh drain and vent open. Never had a problem in any climate.

Exactly. Even if some water is still in there and freezes, who cares? Its not under any pressure, even if it freezes solid.

[mjones12]

Originally Posted by KFX450RXC

Exactly. Even if some water is still in there and freezes, who cares? Its not under any pressure, even if it freezes solid.

Correct.

[wogden]

On our FR3100 there is a short line from the fw tank to the pump. There is a small plastic in line filter right by the input to the pump. Last year a bit of water got into the small filter and broke it in half. This year I am disconnecting the input to the pump and pulling the cover off of the filter to save me this aggravation. I do not put anti freeze in our fw tank.

[A32Deuce]

This past January, we camped in Gettysburg with a full fresh water tank and it was 16 in the am.. Didn't freeze, just used unit heater over night.

[A32Deuce]

Originally Posted by wogden

On our FR3100 there is a short line from the fw tank to the pump. There is a small plastic in line filter right by the input to the pump. Last year a bit of water got into the small filter and broke it in half. This year I am disconnecting the input to the pump and pulling the cover off of the filter to save me this aggravation. I do not put anti freeze in our fw tank.

I found on mine, running the pump a couple times while blowing out the lines gets the water out of that sediment filter.

[5picker]

Originally Posted by CoMaddMax

"Never had a problem in any climate." Hi NMWildcat I see you live in southern NM and I see the original post lives in Ohio where they have sub zero temps.... How cold does it get in southern NM?

I live in the mountains of PA and we get plenty of sub zero weather.

For 40+ years I've never added R/V to the fresh tank and never had one crack or any other problem.

I drain and leave the drain valve open (with a screen cover over it) and don't worry about it.

[NMWildcat]

Originally Posted by CoMaddMax

"Never had a problem in any climate." Hi NMWildcat I see you live in southern NM and I see the original post lives in Ohio where they have sub zero temps.... How cold does it get in southern NM?

Sorry, missed your 'comment'. You assume since I currently live in a warm climate, that I always have. Do you have any worthwhile comments/suggestions?