A filtration system includes two end manifolds formed from blocks which are adapted to receive two or more reverse osmosis filtration tubes and to provide separate flow channels for the feed and filtered flows through the tubes. The end manifolds are machined from a block of nylon or similar resilient material and have cylindrical grooves formed to receive the outer and inner tubes of the filtration tubes and annular grooves formed within these cylindrical grooves to restrain O rings which seal the outer and inner tubes have channels formed between the cylindrical grooves which receive the outer and inner tubes of the filtration tubes which channels provide separate flow paths for the feed and filtered flows.