I have a 2006 Chevy Colorado with a crew cab and I discovered a water puddle on the carpet on left side near the left rear door. I thought someone spilled a water bottle so I soaked it up with a towel. I took up the floor trim near the doors and saw water was everywhere. The underlayment under the carpet was soaked all the way from the back seats to the front floor boards. I thought maybe the door weatherstrip was bad letting water in. I went on the internet and found numerous water problems with the Colorado. I took the truck to a shop that has done work on my truck and told them about my water leak. I mentioned to check the third brake light on the top back of the cab as this was mentioned as a problem for water leaking in. They had to take all the seats (4) out and take the carpet out to let it dry. They ran water over the cab and sure enough it was running down the back top where the third brake light sits. They had to replace the underlayment and get a new rubber seal for the brake light. The seal was around $15, but it took a lot of labor to do. They said that this was probably leaking for a while and the last big rain we had made it visible on the top of the carpet. Total cost was $430. I suggest to everyone owning this truck to check under the carpet for a soaking underlayment. If you haven't replaced the seal on the brake light, save yourself some money and replace it before it leaks.