The Passanger Foot Well in my Mazda 3 (56) fills with water - any ideas?

Yep Your floor vents from your heating system are leaking when it rains or snows you'll have to go to the dealer and have it fixed.

Don't let the water go to waste, get a goldfish to keep you company on your journey, & feed it the crumbs from your Maccydoos burger.

I had that problem with my first car - Austin 1100 - but that was caused by holes under the wheel arch letting water into the cab when it rained- up as far as the brake pedal on a couple of journeys. Cured it by drilling a 1/2 inch hole in the floor. A bit drastic with your 4 year old car though!

Roll all the abode windows up tight, get interior and characteristic somebody spray water with a backyard hose around all the door seals, possibly use a flashlight to look. in case you do no longer see any water try looking under the motor vehicle there could be a floor plug unfastened or out.

Air conditioner drain is plugged, Windshield is leaking, cowl drains are plugged, sealer missing at some point in that area. There are so many places for water to enter a modern car, the possibilities are endless. Does MAZDA have any service bulletins about this? A top notch service dealer can tell you if there is a service bulletin on this issue.

most likely ur heater core has gone bad......pretty expensive labor to part cost ratio on these......usually the part is less than 50 bucks but the labor will run around 800 cas u have to take dash apart to replace them.....

Your passenger needs to see a doctor about this.... and you need to drive slower.