really bad water what to do about system?

There are portable water softeners for RVs that work well. I used a 5 micro sediment filter (whole house GE Smart Water housing with hose fittings added) before the softener to keep crud out of the softener resin beads. That will remove some visible rust but no soluble rust. There are special filters and cartridges that will remove rust. See HERE for the housings. The site also has cartridges.
We were volunteer camp hoses at an Idaho state park one summer that had a high concentration of rust. We had rust deposits on the shower walls, toilet, and sinks. When we left and got to my sister in laws orchard I got a quart of Iron Out and spent half a day getting rid of the deposits.
Because of the fumes I put on a hazardous material mask my sister in law used for spraying agricultural chemicals.

You can try a 1:1 mixture of vinegar and water. First clear the system of all water. Then put the vinegar solution in the system and run until it some out every faucet. Then wait a few hours - 3 to 4 will do it. Then flush the system with fresh softened water.

To prevent this in the future, use a sediment filter to a charcoal filter to a water softener and then to the RV.

path1 wrote:
Besides sanitizing fresh water system is there anything I should do about really bad water (rusty, hard, etc) for 4 months. Can I get out hard water deposits?

Used RO water for drinking and cooking. All other uses for water was thru RV water system.

Thanks

We winter in south Texas and the water down there is really rank. Eats the ends off your hoses in a year and those "Y" connections are history as well. I use a sediment and a charcoal filter for the whole unit and I have an RO system for drinking. The plumbing in the coach does not seem to be affected. Cheap pot metal fixtures corrode but the Moen stuff seems unaffected. I've never noticed anything in the Pex lines and don't think they are bothered by it.

I don't do anything special. Just sanitize the system at least once a year, flush it out every now and again and call it good to go.

For drinking, we carry our own and don't rely on the fresh water tank. With our 5er we have to room to do it and it's worth it.

vinegar is effective on hard water

You could run some dishwasher cleaner into the pipes and let it sit, then re-sanitize the system.

Are you using a water filtration system? Pur makes an excellent whole house system that covers water from both your tank and pressure water supply or you could get a small filter that fits just by the place you want to protect (like the kitchen sink). You could also get a portable filter system that simply attaches to your water connection provided you don't camp in areas that don't have pressure water. Lots of options based on how you plan on using your RV.
Good luck / Skip

Hard water deposits are all but impossible to remove. If they get bad enough, the only solution is replacing the plumbing.

You can get small water softeners, however, that should prevent THAT problem. But if your system is already full of crud, you are probably out of luck. On the other hand, water so bad it kills a plumbing system in a mere 4 months is really hard to find.

Rust stains in sinks and toilets might yield to some oxalic acid or muriatic acid. Do be aware that the latter will stink you out and must be used ONLY WITH ALL doors and windows wide open, and a fan blowing to boot. In addition, both should be flushed out of the waste tanks immediately, don't let them sit down there. Whatever you do, do NOT put either of those in the hot water tank, as they will ruin it by themselves.