Need to repipe 2nd floor apartment-rusty/yellow water in shower-HELP-

3 flat apartment building have rusty/yellow water/scalding appears to be advance stage of corrosion in shower. 2 Plumbers have looked at it and repiping specialist. No access except right through the walls through 3 apartments to replace pipes. Will my homeowners policy cover anything. This is a real mess to get access to the walls where the plumbing is located. Please advise.....