I noticed the carpet in the boot of my mazda 626 was wet. on lifting it to investigate i found both side compartments and the spare wheel well were all filled with water. took it to a garage but they failed to diagnose where it was coming in. since then i have also discovered carpets are wet in front and back of car. no visible signs of water coming in all seems to be at floor level. my car is old but i love it and want to get it fixed!!!!

 

If you noticed the front area carpets being wet well after being wet in the back then there is a very, very good probability that the leak is in the boot/trunk area. I like that, "boot". If the spare tire well and side wells are full of water and you are driving along and step on the brakes then the water will slosh forward and start soaking the front carpets and under the rear seat. Are you able to check under the rear set cushion to see if is wet as well? If so then definitely coming from the back and moving forward as leaks from doors etc would not be able to run uphill to the undercushion area. Rear tail light gaskets are very common on older 626 model to leak water. The trunk/boot seal should be much more noticeable as you can visually check for damage. Try getting that rear trim off so you can see the backside of the tail lights, dry the area and then use garden hose to throughly soak area around trunk and tail lights and then see if water is running in thru those gaskets. What year 626 do you have britbabe?