I was just told by a GW owner that his porta potti is plumbed thru a macerator pump for an overboard discharge. I was not aware of this feature. I thought conventional marine heads were the only fixture designed to discharge overboard. Can anyone confirm this? Do the marine toilets discharge to a holding tank prior to going overboard. I had an Ocean Alexander years ago and the toilets discharged to a holding and the overboard valve had to be secured in the off position in Puget sound..