Any number of the consumers of water from any canal, ditch, conduit or reservoir, or any lateral or distributing conduit, receiving water from any such works, may in writing agree among themselves for the rotation of the water to which they are severally entitled, and the delivery thereof upon particular days to particular consumers during such seasons, season or part of season, as in such agreement may be specified: Provided, That the rotation of the water to which the several consumers, parties to such agreement, may be entitled, shall not be conducted in such manner as to diminish the supply of water to which any other consumer under such canal, ditch, conduit or lateral may be entitled.