Omni-Tech jackets, made by Champion, are designed to be waterproof. They are also air permeable so moisture vapors can escape, allowing you to stay dry from the inside out. Just like with most other types of waterproofed gear, Omni-Tech jackets have a durable water repellent, or DWR, finish on the outside. This finish may deteriorate over time, but that doesn't mean your jacket is no good. You can restore the DWR finish on the jacket to make it waterproof once again.
Empty all the pockets of the jacket. Close all zippers and fasten any buttons on the jacket.
Place the jacket in the washing machine. Run it through a complete wash cycle using warm water and mild powdered laundry detergent.
Tumble dry the jacket on low heat in the dryer until it is completely dry.
Lay the jacket flat on an ironing board and iron the outside of the jacket on the low steam setting. The heat from the dryer and iron will reactivate the DWR protective coating if it's still present.
Check the jacket after washing, drying and ironing to see if the DWR finish is still intact. Place a few drops of water on the jacket. If the water beads up, the waterproof finish is still active. If the water soaks into the fabric, the finish will need to be reapplied.
Purchase a spray-on finish if the water soaks into the fabric. Read the instructions for applying the product, as this may vary among manufacturers. Generally, the product is sprayed evenly onto the outside of the jacket while it's wet, then the jacket is dried on medium-heat in the dryer.