I doubt that you're entitled to anything off your rent for this.  But I don't have a copy of your lease to review, and I'm not familiar with the details of California landlord-tenant law.  For advice you can rely on, you would need to have a lawyer in your area review the lease and all the facts of this situation.  One place to find an attorney is our website, http://attorneypages.comIn most states, I think that the pool would be considered just an amenity, not an essential part of the bargain made in the lease.  That goes more to habitability issues, shelter, security, indoor plumbing and utility service.