When it rains the driver and passenger side floor

Check the cabin air intake. Chances are the weather strip that lines part of the opening has come off. The intake should be accessible beneath the trim at the base of the windshield on the passenger side.

A water leak under the dash could be the heater leaking near the glove box, or a windshield leak, or sometimes the drain tube for that area has gotten plugged up and needs to be cleared out. Most times a little blast of air pressure will do it.
Hope this helps.

GM cars used to be notorious for leaking rain water in around the edge of the front windshield. There is also a rainwater drainage system on the front, generally where the wipers are located and the drain hole on the bottom of that can become clogged.

windshield gasket. if windshield was recently replaced, it was not installed properly. get it fixed quick or it will rot the carpet, rust the floor, and possibly cause massive electrical problems

bad door seal, floor plugs bad, open holes in firewall on rh side

Check the front 'cowl' area, (located between the hood and the windshield). A lot of junk can accumulate inside through the slots. This is where air is drawn into the car for ventilation. If leaves and pine needles build up inside, it can rust through, allowing rain into the vehicle. Also check under the hood, near the passenger compartment, at the fire wall. I have a 96 Pontiac that leaked there into the drivers side due to rusting from leaves and junk. You should also check the windshield seal, and possibly the door seal, as water could enter from one point and travel a ways before hitting the carpet. You might also want to have someone hold a hose on the car, in one location for a while, to see if you can narrow the possible locations. Good luck.

You have a leaking windshield seal at the bottom of the windsheild rain gutter.

Did you have the windshield replaced recently? This is typically caused by faulty installation of a windshield. Sometimes it can be fixed by adding windshield sealant (polyurethene, not silicone) where the windshield is adhered to the subframe - most likely along the bottom edge.

Is it possible the water is actually coming from the A/C evaporator case, whose DRAIN IS CLOGGED ? The water produced by the A/C then leaks out of the case, down under the carpeting, then depending how vehicle is parked, can flow to the rear floors and carpet. Hope this helps

Hi, we also have a 2002 Toyota Rav4 and developed a leak in the front driver's side of the car. After much research, we discovered that the drain wells from our sun/moon roof were clogged. If you have one of these, I suggest that you open the sun roof and look carefully. You will notice some tiny little holes in front and in the rear of the sun/moon roof tracks. Over time, these become clogged with dust and debris. You need to find a long, sturdy piece of thin wire and run it down the holes. To test if you have properly unclogged these, take a small amount of water and pour it down the holes. You should see water coming out of the drain wells under the car around the rear of the front tires. Hope this helps.