Legal Question in Real Estate Law in California

I'd be a little hesitant to be specific without more information, such as why the water heater became broken, whether the landlord or property manager has been notified, and whether repairs (or replacement) have been scheduled or promised. Perhaps this is a "repair-and-deduct" kind of situation, possibly you are entitled to use a motel or even "break" the lease and move out. Also, how you feel about the place and the landlord would play a role. Probably in the majority of cases, "grin and bear it" is the correct response, but this assumes the landlord has been notified, has agreed to fix the problem, and is actually arranging or has arranged for a prompt replacement or repair. There is no "one size fits all" answer after only five days.