I'm sure this is a dumb question

Thanks for all the responses. It got down to about 27 last night and will again tonight. I am going to fill the fresh water tank today.

How freezing is freezing? 32 degrees or 25 degrees? and what is the forecast for the next day?

If you are using it, I would not worry about dipping below freezing for short periods. I take ours into the teens overnight with no problem, as long as it is warm inside. If you have it cold just sitting, I would worry then.

Bryanpark2's profile shows a picture of what he has. That should help to answer his specific question.

It sounds like you're using the camper? Heat on? If you're 'camping' answers will vary more than if you have the trailer parked and just want use of the toilet...what kind of unit-make model, will help as well.

Your fresh water tank should have a drain.

consider this simplified water diagram of a typical trailer setup...


Roy Ken

If you are not connected to fresh water, all of your water is being supplied to all faucets by that pump. The low point drain will not empty your tank in most coaches, just allow the water in your lines to drain. It's possible yours is setup differently, but if that's the case you will need to pump the water in the holding tank out.
Doing this DOES NOT leave your coach "winterized" as some water will remain in parts of the coaches plumbing and not doing a blow out or pumping RV antifreeze into the lines will lead to disaster when the temps drop.

Open the gray water valve and turn on a faucet or two. The low point drain is for the plumbing and it sounds like you will still be using that tomorrow.

The low point drain is generally for the plumbing and hot water heater. The fresh tank should have its own drain.