I've noticed that my front passenger carpet and mat are soaking this morning. My cars a 53 plate sti. Any help will be a appreciated!

 

There's a grommet on the back bulkhead which protects the fuel lines check to see if its come loose and letting water in ,pull the carpet back and check the floor pan as there are numerous floor grommets but doubt it will be one of those as they are in pretty tight.

Is it coming in from the front scuttle panel ?

 

Is your heater ok not lost a pipe from the matrix ....

 

Has it ever had a new windscreen?

Taste the wet. Seriously...if it's sweet-ish, it's coolant and shows a matrix leak.

 

My first thought was heater matrix. Taste the water and see if it's sweet. If it is that's coolant.

 

A perished window seal could also be the problem.

 

The heater still blows hot, the windscreen is still the original genuine Subaru one. Looks like there's a grommet in the floor by where its wet, so ill check this Sunday when I'm off. The carpet is dry by the sill and bulkhead. Ill have a good look and let you know what I find. Thanks for the advise!

 

as already said maybe the bulkhead gromit you can see it from the bay, alot of people use it to feed amp power cable through causing a leak