I'd be inclined to treat it since you don't know what's in there. Here is a link to howto https://www.sanidumps.com/sanitizervfreshwatersystem.php or there also was a post here about using vinegar https://forum.loveyourrv.com/discussion/496/page/p1

As far as drinking out of it, depends on the quality of water that goes in, its really just a big plastic jug. :) We usually purchase drinking water from the machines and store in separate jugs, Anne has a sensitive stomach and taste buds. ;) She can tell the difference in water and likes the purified stuff better. Also when traveling it's no fun getting sick from bad water. ;) But I know many that do drink from the onboard tank.

Also when back home in BC on Vancouver Island I drink right from the taps, we have terrific soft rainwater there, tastes great. But when down in the southwest where much of the water is high salts and mineralized well water I don't. So basically it depends on the location water quality and how sensitive your taste buds are. Personally we are pretty spoiled. ;)

I treat my fresh water tank with bleach (and so should you) and I think it is safe to drink from the tank. However, we usually drink bottled water. It’s just our preference.

Here is a video I made on how to sanitize the fresh water system.

Thanks Ray for the info, will also check out the video link. Mike

Thank you for the info Logan, and I will check out your video. Mike

Logan, I watched your video which was great. I also loved your
wife's beautiful patio. Thanks again. Mike

thanks Mike. My wife appreciated the shout out.

I treat my fresh water tank twice a year. I have a camco hose filter and a whole-house filter that water goes through before it gets to my water tank. Inside the RV I use the tank water and filter it through 2 Brita pitchers and it's fine to drink. Other folks use Burkey water filters but they're expensive and rather large.

Good luck!

Before heading out, we always bleach our fresh tank. When camping, we use our tank and pump rather than direct supply hookup so the water is constantly changed in the tank and pressure is always the same. We drink purified water only; not tank water. There is too much variability for our taste. When back home, if weather permits, we keep the tank full (you never know when you may need it). We do drain it every 4 weeks or so and refill to keep it from getting stale.

X 2 on the bleach treatment. Just a little dab will do ya. BTW, I have read that, in a pinch, you can drink clean-looking water from a flowing creek or river with a very low risk of getting sick. Just avoid standing water or any that looks or smells yucky.

We operate a fifth wheel unit where I designed and installed a dedicated 12 volt drinking water system. It started with the 12 volt pump (an on demand pump - so once you turn the power on it will shut off automatically when you close the faucet valve) and setup for 5 gallon water jug(s) 2 in the basement area and available for refill or exchange across the country. I also installed a dedicated small faucet at the kitchen sink - we fill for our cooking needs and individual water bottles from the faucet. The only challenge we had was we shifted brushing our teeth to the kitchen sink. I may look to plumb a faucet to the bathroom sink - just tight on space in the bathroom sink.
Pump system was a little spendy (make sure to get the 12 volt model so you can boondock easily) but well worth it for our family experience. We do about 40+ days at a time each summer as a family of three. We still fill the water tank for showers etc as well as sanitizing the tanks as others have described.
Bottled Water System- Filtered Water Delivery System with Single Water Inlet for Home Use, a U.S. Solid Product https://www.amazon.com/dp/B073C3SQHX/ref=cm_sw_r_cp_apip_1QeuoTYagyZVE
Aquaboon Water Filter Purifier... https://www.amazon.com/dp/B07DHZBHKJ?ref=ppx_pop_mob_ap_share

When I fill up at home (chlorinated city water) I don't worry too much about using that water. If I travel and fill up somewhere else I use mostly bottled water. I filter everything I use for cooking.

Thanks to everybody who responded to my question: A lot of useful information.

Mike