Horrendous smell and pink water coming out of FW tank

Definitely sanitize the tank. RV Antifreeze does don't have a vile smell, that's for sure. It most likely is RV Antifreeze, but could have something else in it that makes it smell so bad.

-Michael

Fill/drain fresh water tank several times..
Then fill fresh water tank and using pump run water thru system hot and cold (hopefully water heater was BYPASSED) until pink is gone...then flush water thru 'low point drains'

Then sanitize system
1/4 cub bleach per 15 gallons of water (how big is your fresh water tank....fill with bleach solution) then using pump run bleach solution thru hot/cold water lines (water eater bypassed) just enough until you smell the bleach, also thru low point drains.
Let sit for 4 hours then drain/flush fresh water tank.....then fill and flush system hot.cold...low point drains

May take couple times to get rid of that 'vile' smell

Yes antifreeze is the pick stuff.

Antifreeze has a smell, usually sweet and can be sickening to some people. Side note: Different brands have different smells to them, I cannot stand the smell of one of the brands that is for sale around here.

Other smell could be water in the fresh water tank gone stagnate, fill up, drain do this a couple times, then fill up and add a cup of bleach and let it sit for a day and drain and flush a couple of times.

The other area could be the hot water tank. Mine on my TCer would sulfate and would STINK!!!!! Would have to flush a couple times completely with fresh water and then with some bleach mixed in with the water till it would stop. My wife always thought it was me that smelled so bad :-)

Like other said, flush and sanitize (with a bit of bleach - lots of threads on it). Not a bad idea to do it annually, either.

Flush it out as recommended above (probably the water heater too, no need to turn it on). Then sanitize the system--many threads here on how to do that.

You have a combo of RV antifreeze and a tank with stuff growing in it.

since the previous owner didn't have/use a winterizing kit, buy one $20 or so, and do NOT put antifreeze in the fresh water tank.
bumpy

Some winterized it by putting antifreeze in the fresh water tank. Just flush the tank several times, and the taste will go away eventually. You may be new, but you have just learned one of the first things you need to know about winterizing RVs.

x2 on it being antifreeze. It's non-toxic (at least in modest quantities), but not very pleasant.

I'd suggest draining the fresh water tank and hooking the hose up for city water usage (not using the tank) and flushing out the plumbing. It will go a lot faster if you drain the water heater and bypass it to flush the plumbing system, and then un-bypass and refill it (after putting the drain plug back, of course). Be sure that you don't turn the water heater on when it's not full of water, whether on electric or gas heat if you have both. If you don't empty the tanks, it will take a very very long time of adding and removing water from them to get the antifreeze diluted enough to be unnoticeable.

It's AF but antifreeze doesn't smell "vile". I'm thinking the system needs to be sanitized. Which I would do to any RV I bought - new or used.

It's antifreeze. Just run water through the system and it smell and taste will eventually go away.