My 90 BMW 730I SEauto has mucho water on carpet of footwell of rear left seat-what could be causing

1990 BMW 730i SE auto

My 90 BMW 730I SEauto has mucho water on carpet of footwell of rear left seat-what could be causing that?downloads

heater is leaking

My 90 BMW 730I SEauto has mucho water on carpet of footwell of rear left seat-what could be causing that?house call

Worn/leaky weather strip on rear door/window.

Compounded by use of power washer/high powered car wash maybe?
clogged or dislodged sunroof drain probably.
Snowie must be correct.Even others are right too.

But is this happening on rainny days or even dry weather..

If always,it could be from the air condition chiller drainage.

If on rainny days,get the car for Highpressure car wash,and one person stay inside the car to observe the flow.

You can detect it.

good luck.
The vapor barrier (a sheet of film inside the door) is probably loose/leaking.