by Conrad & Judy Kreuter
Dear Boat Talk: This is my first boat that has a pump out porta potti. Can you give me some clues on the proper operation and maintenance of this type system? JM, West Babylon NY.
Dear JM: Of the various sanitation systems found in cruising boats yours is a combination of the very simple porta potti and the holding tank systems.
A porta potti is the most common type head found in boats today. They consist of two chambers, an upper tank that you fill with holding tank deodorant and water. When the potti is used, a flush valve allows the waste to enter the lower chamber where it is stored. When the holding tank is full the two halves of the potti are disconnected and the holding tank portion is emptied, usually into the household septic system. The two halves are joined after the upper half is filled with a new solution of deodorant and water. A system of this type will usually be sufficient to last the average boating family about two days of use.
A porta potti in combination with a larger holding tank located somewhere in the hull will enable longer use before the tank must be emptied. Depending upon the size of the holding tank and the amount of use, it may take a few weeks of weekend use before waste removal is required. Because this type of system cannot be easily removed from the boat, you must go to a convenient location that has pump out equipment to remove the waste.
Holding tanks can be under a significant amount of pressure. Once the tank is full, opening the deck plate to begin the pump out process can bring new meaning to the term s—t faced.
Twenty-five years ago before pump out stations were required, a friend of ours had a system consisting of two big “honey buckets”, a manual pump, and hoses, that he used to extract the waste from the holding tank. At the end of his boating weekend he would empty the holding tank, into the “honey buckets” and dispose of the waste at home.
One weekend he entertained a few families with small children. The children’s experience with the potti was like a new game. Unbeknownst to the boat owner, the holding tank was filling fast. The pressure in the tank was at an all time high causing seepage from the deck fitting.
Our friend went up on deck to pump out the holding tank. As he loosened the deck plate, a geyser that would put Old Faithful to shame rushed forth throwing the contents of the holding tank far into the evening sky creating a shower that covered three other boats in every direction!
Holding tanks should always be emptied for winter storage.