Abstract: For use in connection with a water supply system wherein pumping means draws water from a source and supplies it to various consumers by way of a main and branch lines from a main, a supplement to said supply system including a tank forming a first large standpipe for storage of water and a second smaller standpipe. The second standpipe is positioned within said first standpipe to project upwardly from and perpendicular to its bottom to a level approaching but spaced from the top of said first standpipe. A distribution line is provided one end of which opens into the bottom of said first standpipe and the other end of which is arranged to connect to said main. The lower end of said second standpipe, which opens from the bottom of said tank, has coupled thereto one end of a first flow line the opposite end of which is arranged to connect to said main.