On ALL RVs that carry fresh water in onboard tanks, there MUST be a drain, usually a "quarter turn tap," like this on towables, but sometimes elsewhere and a different kind on self-propelled ones. It will be located somewhere as low as possible, and on towables is usually at the front, below the hitch bar. This tap only drains the fresh water tank itself.

The fresh water tank will have a "fill hole" that's around 2 inches in diameter so you can "pour" water in or insert a hose to fill.

The RV quite probably also has a pump and in the US usually will have a hot water heater, and considerable other "plumbing" that will need to be separately drained. There usually is a hose connection to connect a "garden hose," here usually labelled "City Water." This connection will normally be on the opposite side from the fresh water tank, since it is intended to be connected from a supply tap that's normally near the same place you connect your external electric (AC), and filling the fresh water tank usually produces significant spillage.

There likely will be two additional drain points that just look like a couple of "water pipes pointing down" with "caps" on the end, although some may have had taps installed that's are just a valve you can turn on or off. These usually will be close to the hot water heater tank. One pipe drains the cold water supply and the other drains the hot water side of the system.

The hot water tank also will have its own drain plug, also sometimes with a valve installed but as often just a (male) plug screwed into the side of the tank.

ALL OF THE DRAINS must be opened, and faucets etc inside turned on to let as much water as possible drain out before storing the RV any time freezing is possible.

Additionally, at least in the US, most people put a "hose adapter" on the "city water" (hose connection) inlet**. The adapter has what looks like an "auto tire valve stem" you can connect an air hose to, to blow as much residual water out of the lines as possible. When each drain "blows dry" you may need to put it's cap/plug back on loosely, to get enough flow to fully clear the next line, and may need to "cycle" the faucets, for reasonably complete clearance. (You'd usually remove all the caps/plugs when finished. Just don't lose them before you fire up the next time.)

"RV AntiFreeze" is available here, all of which claim to be safe for potable water tanks but most people here put it only in the "blackwater" (body waste) tank, in the "greywater" (sink drain waste) and in the sink/tub U-traps. The fresh water storage trap is usually just drained as completely as possible, and all of the lines "blown dry."

Some people do put the "RV Antifreeze" in their fresh water tanks, and that may be the odor you smell. The usual recommendation on the jugs for cleaning the system when you're getting ready the next season is that you:

- drain completely,
- refil the fresh water tank and
- drain again
- repeat

You may want to cycle the faucets (with pump on) each time you fill, to get residuals out of the lines, as well.

It's most likely that the odor you're getting is from "RV Antifreeze" that was put in the tanks. You might want to just get a jug of it for "comparison sniffing" before proceding to extreme measures. Most of it smells pretty much the same.

(According to the experts, you should have a female help with the sniff test, since usually they're more subtly attuned to offensive stinks - possibly an evolved feature in order to detect dirty old men.)

** Note that in the US and Canada, the "plumbing" in RVs is generally designed for a maximum of about 50 psi. Most city water systems run at 30 to 45 psi, although there are higher pressures on some local systems. Should you use the RV at "fairgrounds" or "parks" the water outlets may be at 150 psi or higher for their "industrial sprinklers" and could bust your internal plumbing and/or make you hoses look like an anaconda that's swallowed a pig. If in doubt, you'll want a "regulator" on the inlet to your hose (good ones abut $9.00 US here) to protect the system. They're usually preset at about 40 psi. (I carry a water pressure gage to check before connecting.) You also probably don't want to use air over about 70 psi to blow out the lines when you winterize.

John