Use this excellent product to find pin hole leaks in breatheable and waterproof fabric. Just spray it on the suspect area and see the leaks on the other side. On Gore-tex waders spray on the inside and black dots appear on the inside.
The breathable fabric is hydrophobic, so when you try to find a pin hole in you waders under the kitchen tap, the water is repelled from the small holes and forms spheres of water which role off the fabric. It is only when the leak is under a meter or more of water pressure that the water will be forced through the pin holes and onto your feet ( i.e. when you are waist deep in water in your waders!)
Once the holes are identified you can repair the area with a repair product.