If there is a leak in my apartment and the landlord doesn’t fix it, can I withhold the rent until the leak is repaired?

In every lease there is an implied warranty of habitability which requires the landlord to maintain the premises in a habitable condition by complying with local and state housing codes.  When there is a breach of the implied warranty of habitability, the tenant notifies the landlord and the landlord is required to respond within a reasonable time by making the necessary repairs.  When the landlord fails to respond within a reasonable time, the tenant has the following options:  The tenant can make the repairs (call a plumber in your case) and deduct the cost from the rent or the tenant can move out and terminate the obligation to pay rent for the balance of the term of the lease or if the tenant stays on the premises, the tenant can withhold rent and defend against eviction.  Other alternatives would include suing the landlord for breach of the implied warranty of habitability, contacting the local housing code inspector to take enforcement action against the landlord for housing code violations, etc.

Not all maintenance problems rise to the level of a breach of the implied warranty of habitability.  For example, if the leak in your case is a faucet dripping, that does not constitute a breach of the implied warranty of habitability.

If the leak is of such magnitude that it presents a health or safety issue, it may be sufficient to constitute a breach of the implied warranty of habitability; however, moving out or withholding rent because a faucet is dripping  would not be appropriate.