Why is my dusters glove compartment full of water?

There is a dam under the cowl and a drain at the end of the cowl. A loe of these cars are rusted through around the dam. and or the drains are clogged. The did notpaint under the cowl and it is always seen the elements if not Garage kept. Here are pics of what i am talking about

The easy fix is jack the car on one side. Plug the drain on the other side. Pour a gallon of POR15 down the cowl so it fills the rusted area . Unplug the drain and catch the POR15 to do the other side. This will stop the rust. Put POR15 around the same area in the car. This will seal the rust . you can now seal it on the inside. I mention using POR15 just because most people know of it. I use Chassis saver

Here are some pics of what it looks like under most cowls