if the plumbing in my home needs serious repairs is the landlords insurance responsible for relocation costs?

If you have a residential lease for a certain amount of time and the lease is interrupted (by you being forced to move from the home due to faulty plumbing), you may be able to obtain monies from the landlord for your relocation expenses and any associated damages.  It is unlikely that the landlord's homeowner's insurance would pay such a claim - unless the landlord carries such rental insurance coverage.  If you have your own renter's insurance policy, the policy may cover such relocation expenses.  Coverage will be determined by the terms and conditions of the relevant insurance policies.