I hate to get up on my soapbox but I keep seeing people recommending Jeyes fluid to clean up cat wee. Jeyes fluid contains a chemical (carbolic acid) which is a phenol and these are toxic to cats, as are all disinfectants which go cloudy in water (eg Dettol, TCP).
Even when rinsed away, the traces left behind are still poisonous.
There's a very good factsheet on common cat poisons from the Feline Advisory Bureau here (yes, that is FAB for short) if you're interested