Clogged drains can allow rainwater to accumulate in the plenum tray (at the base of the windshield). The water may leak into the vehicle's interior, brake booster, or electrical components, which can lead to major problems. Our technicians recommend keeping the tray clear of leaves, pine needles, and other debris.Google+
Car Problem Reports
Audi A6 Rainwater May Accumulate in Plenum Tray Due to Clogged Drains
Audi A6 Problem
Average Mileage: 125,000 mi (110,000 mi - 140,000 mi)
Visitor, 2004 Audi A6, 140,000 mi
water in rear nearside (uk car) passenger footwell after heavy rain.this car is always serviced by an Audi main dealer,do not assume that they will clean the drains as recomended the leaves in mine had turned to compost they had been there that long.