Method and assembly for water filtration using a tube manifold to minimize backwash

A method of filtering a feed liquid, the method comprising:

• introducing the feed liquid into a filtration chamber of a membrane filtration system including:
• a membrane module having one or more permeable hollow membranes extending between an upper header and a lower header of the membrane module, the membrane module being located in the filtration chamber, the filtration chamber having an open upper end located above the upper header of the membrane module and a closed lower end and a feed tank surrounding the filtration chamber and configured to provide the feed liquid through the open upper end of the filtration chamber;
• allowing a gas to flow into and out of the filtration chamber through a valve at the upper open end of the filtration chamber;
• providing the feed liquid to the filtration chamber such that the valve at the upper open end in the filtration chamber closes and prevents liquid flow out of the filtration chamber;
• applying the feed liquid to surfaces of the one or more membranes within the membrane module;
• pressurizing the filtration chamber and producing a pressure differential across walls of the one or more membranes by continuing to provide the feed liquid to the filtration chamber;
• filtering the feed liquid through walls of the one or more membranes into lumens of the membranes as filtrate;
• and
• withdrawing the filtrate from the membrane lumens of the one or more membranes.