Ist it recently only or it has been like that all the time?? If recently your cat behave such way, I think because the weather is very hot lately. I noticed my cats drink a lot of water and eat less too. They pee more than poo.

Even the strays that I've been feed regularly need more water nowadays. I put 02 big bowl of water for them instead of their usual 01 bowl of water.

My cat managed to escape the house twice now.
The first time, he got the right unit, but on the wrong floor haha.
The second time, he was hanging out outside of the house, waiting for me to open the door.
So yes, I think that it's possible.

By the way, just in case you live in a landed unit, I used to have a cat who would always go back to our old house.
Do note that we have moved to a new place.
& the old house was pretty far from the new one.
Either he has a map, or is really good at finding his way 

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Added on May 23, 2012, 11:17 pm

If it's sudden behavior & he/she looks unhealthy, you should bring him/her to the vet.
Otherwise, don't worry about it.
Your cat must be very thirsty because of the weather.