Welcome ! From another Iowan to another !
everything trudinator said is spot on !
only thing I can add is if the rv antifreeze was dumped into fresh water tank you need to open your fresh water tank drain and get as much as possible out .
the other thing is there may be a water filter canister installed and you will need to reinstall a new filter which can be found at wall mart .
heres what you will be looking for and at . also there may be a strainer that needs to be cleaned. (last picture)
good luck and hope all goes well !