1. The water tap is broken. The landlord refuses to repair it and there is no water coming into the flat. Is the landlord in breach of the covenant of "fitness for habitation"?
The implied covenant on the landlord that the premises is fit for habitation only applies to furnished tenancy and only at the commencement of the tenancy. Such covenant does not last throughout the life of the tenancy.
So where the water tap is broken during the currency of the tenancy, the landlord is unlikely to be in breach of the covenant as to habitability.
In fact, whether the obligation to repair the broken water tap falls on the landlord or the tenant or neither of them is to be determined by reference to the specific provisions of the tenancy agreement.