A properly functioning septic system shouldn't ever need to be pumped, but you bring up a valid point. In fact, everyone in NC I knew with a septic tank has needed it to be pumped multiple times over the last year due to all of the rain. I hadn't thought of synthetic fibers at all, thank you for mentioning it. We are trying to not buy any more synthetic materials whenever possible. It's amazing how pervasive petrochemicals really are.