No. All of our bags are made of 3 layers that are bonded together; the outside Canvas or FibreNyte, a middle layer of butyl rubber and the internal lining. It is this middle layer of butyl rubber that prevents water passing through, therefore your bag will not need re-proofing.
We strongly recommend not putting your bag in a washing machine or exposing it to harsh chemicals as this will break down the butyl rubber and therefore the bag will no longer be waterproof.
If you get a hole in the fabric, this can also mean the bag is no longer waterproof and we recommend contacting us as we offer a repair service.