hiya,
my car is leaking water whenever there is a heavy rain from under the steering wheel. it leaked like a half cup of water overnight onto the floor mats. It does not leak when driven . What could be causing this ??

most likely the front windscreen seal as the culprit.
check for any missing grommets from the engine bay ,then get inside with a torch and look underneath while someone uses a garden hose and gently pours water from the top of the windscreen.
the windscreen seal always seems to be at fault when it comes to water leaking inside. hope this helps

okok... what is a grommet? isit like a rubber plug? http://www.google.com.au/imgres?q=grommet&um=1&hl=en&sa=N&tbm=isch&tbnid=o1zzs4GoqRR5UM:&imgrefurl=http://www.overclock.net/case-mods-general-discussion/729919-cable-management-grommets.html&docid=6kpB71UQlxhorM&w=600&h=527&ei=1IUpTsbHLJCWsgO46pzgCg&zoom=1&iact=hc&vpx=632&vpy=700&dur=9138&hovh=210&hovw=240&tx=97&ty=174&page=1&tbnh=147&tbnw=174&start=0&ndsp=57&ved=1t:429,r:20,s:0&biw=1920&bih=1099

It's the rubber seal around the windscreen also:

http://guyism.com/wp-content/uploads/gromit.jpeg

Take it to O'Briens or something.

You need to work out where the water is coming from.
If the drip is outboard then the likely culprit will be that the heat curing putty that is around the rear of the bonnet hinges.
Try pouring a couple of buckets of water gently at the base of the windscreen closest to the A pillar.

Another entry point is that the soft seal on the windscreen garnish plastic panels have deteriorated. These are about $30 each from a MITSU dealer.
You need to remove the windscreen wiper arms abd then be able to get the tiny cross headed plastic screws out of the scrivets that hold the panel down.
There are also a set of white plastic snap clips underneath.
Gerry

I have "fixed" the leak :D i bought a deep dish floor mat to catch the water. LOL