How do you wash your cars if you live in an apartment and there is no water supply in the carpark?

I used to drive back to my old place and wash it there because had a spare remote control for the garage but they have changed the coding now.

I really want to give my car a good wash myself, I have tried those DIY car wash but how can you do all those claybar.. polish.... etc and wait for them to cure at that place?
It's just not possible..

Anyone have any suggestions?

Do i have to get something like auto washer?? A bit lame though...
Save water - Wash your car with the Autowasher car washer