PURPOSE: To manufacture a water barrier suitable for treatment of water protection of ground surface having good strength and flexibility by dispersing a water-absorbent material in powdered or granular form during the formation of non-woven mat and further laminating a flexible water non-permeable sheet material and integrating structurally.

CONSTITUTION: During forming a mat 18 by depositing fibers 14, 16 of 0.5-25 inches length and 1-5,000 denir onto a conveyer belt 29 through a fiber feeding apparatus 12, 24, the mat is dispersed and filled with powdered or granular water-absorbent material of sodium bentonite or the like from a material storage vessels 22, 26 and also laminated with a flexible water non-permeable sheet and pressed by pressure nip roller 30, 32 and 36, 38. Then, after integrating structurally by interlacing component fibers through a needle punching apparatus 40, a water barrier material is formed by coating and fixing a water-soluble adhesive fed through an adhesive supplier 31.