What are the causes of water ingress in the floor of an Audi A6?

[Marie]

Audi A6 floor water ingress reasons are as follows: Air conditioning drain pipe clogged or damaged: Clogged air conditioning pipes prevent drainage, causing water to leak into the floor, while damaged drain pipes allow water to flow directly into the cabin. Promptly unclog or replace any blocked or damaged air conditioning drain pipes. Corrosion or rust in the front windshield welding: First, use a high-pressure water gun to rinse the surface and observe for leaks. If leaks are found, apply body sealant or windshield adhesive to seal them. Perforation due to chassis rust: Perforations in the chassis from rust allow wheel splash water to enter. Carefully inspect and seal the perforations or install a protective underbody panel. Clogged rainwater drain holes in the scuttle panel below the front windows: Open the engine compartment and clear the debris.