Residual Water in Fresh Water Tank....

[Bob&Joyce]

So, this past weekend I started working on the plumbing issues that I asked about in a previous thread, and made an interesting discovery.

First off, let me say that I NEVER use the fresh water tank for anything. We have never been dry camping or in a situation that I did not have access to a city water connection. However, back in the spring, a service dealer put fresh water in the tank to use in testing the modifications mentioned in the previous thread, rather than connecting the TM to a city water connection.

When I picked up the camper, there was still about a third of the tank filled with water from his testing. When I got it home, I drained the water through the valve under the camper until it quit flowing, and then totally left the fresh tank alone, thinking I had drained the water out of it.

Well, this past weekend in being around the plumbing, I noticed that there was still a fairly good amount of water left in the bottom of the fresh tank - a good inch or more from the bottom of the tank to the top of the water line - that did not drain out through the drain valve.

I have the pump disconnected right now, so could not try pumping the residual water out.

My question: is it normal for some water to remain in the bottom of the tank after draining? It does appear that both the drain hole in the tank and the supply outlet hose to the pump are about an inch or so above the bottom of the tank. Is there some way to completely drain the tank?

It looks to me like if the tank retains water after draining, there is a real potential for freeze problems. I would estimate there is about 2 gallons, maybe 3, left in the tank.

I thought about sticking a tube down the fresh fill inlet on the outside of the camper and siphoning the residual out.

Any thoughts or experiences to share?

I really hope I'm not asking too many questions here, but I appreciate everyone's responses and input.

Thanks

[Redtail Cruiser]

Not sure of the position of your tank, but in my 2720 it is under the dinette seat. If I raise the tongue jack up to the max height, that does a pretty good job of draining most of the water. Many owners, including me, have installed a marine tank inspection access plate. I put a six inch access in the top of my water tank to insure mold won't start growing. When I park my TM for any extended period, I open the access and dry it out completely with paper towels.

[Bill]

Bob and Joyce -

The tank can freeze without a problem since the tank itself is flexible and can bend to accommodate the expanding water. And if you run the pump to the point where it is sucking air, that should ensure that the pump, and the pipe between the tank and the pump, is clear. So no worries there. I don't think we have ever had a report of a nearly-empty fresh water tank breaking from freeze.

The real problem with leaving water in the tank is the fact that crud will probably grow in the stagnant water, as RedtailCruiser mentions. Going through the standard bleach sanitizing procedure will kill the crud, at least for a while. But once it has grown, I don't know of a way to get the dead moss, algae, etc out of the tank without cutting an opening in the top or sidewall.

Bill

[ThePair]

+1 on a WaterSaver. I open it at winterizing time, vacuum out the residual, and wipe out (as best I can) with a paper towel. I leave the seal open for the winter to let the residual water evaporate so there's no moisture for growth. As was pointed out, the issue is not freezing.

In the spring, I drop a scoop of pool chlorination powder in, seal the top, and then fill using the outside port, so as to sterilize the system. Nice write-up here:

http://rvbasics.com/techtips/sanitiz...er-system.html

Getting the powder through the port is a lot easier than any other way into the tank. Once I've resealed the port in the spring, I don't open it again until winterizing.

If you don't want to install or use a port, you could always re-sterilize the tank when you winterize, then just drain it. The little residual shouldn't break anything, and the sterilization should remove the issue of growth over the winter.

[scrubjaysnest]

Since the pump suction line is about an inch above the tank bottom, to prevent sucking crud, the tank will not drain completely. Must of us have installed a clean out plug, 6 to 8 inch diameter, in the tank. The mod is described in other threads.

[tentcamper]

Redtail Cruiser. At our last CS of a trip, before leaving, I open the drain and all the low point drains, and leave them open. On the return trip every hill, braking action, etc.. drains a little. By the time I get home there almost no water left in the tank. I do it so I don't have stale water in the tank at the start of our next trip.

If I had a little water in the tank, I'm with Bill that there room for the ice to expand and would not be concern.