(1) All holding tanks shall be of such design and construction as will allow the complete removal of solid matter that can be expected to settle in the holding tank through an apparatus or device suitable for allowing the contents of the holding tank to be removed from the holding tank.
(2) A holding tank shall have a working capacity of not less than 9 000 L.
(3) Where two or more tanks are used to meet the requirement of Sentence (2), they shall be deemed to be one holding tank provided they are connected in such a manner as will allow the sanitary sewage contained in them to flow between the tanks.
(4) The working capacity of the tanks described in Sentence (3) shall not include any portion of any tank that cannot be completely drained due to the manner in which the connections are made.