My wife's parents live in a mobile home park and they say that they have been notified that they will have to start paying for water a whopping 48 bucks a month (a lot for a fixed income person) and next year 91 bucks. They do have a rental contract for space rent as do all the tenants that says the water is paid by the park. Is this legal and is there anything we can do?

It would be legal if the lease is being renewed at this time. They then can charge you for anything and its up to you to decide to sign the new lease or not. If the lease is not up they should not be able to charge her at this time.