1 ． The water in the impoundments on analysis is found to contain the property of acid -lkali, and harmful substances. The temperature of the water will be changed in the process of the water treatment. So the high anti-seepage requirement is needed. HDPE membrane can resist the acid-alkali and corrosion. it can tolerate the corrosion of chemical medium more than eighty, such as strong acid and alkali. The anti-seepage performance of HDPE membrane is good. The permeability coefficient of water vapor is K<=1.0*10-13g.cm/c cm2.s.pa. HDPE membrane can tolerate the low temperature: the cold brittle fracture temperature is between 60 below zero and 70 below zero. It can also tolerate the high temperature: the melting temperature is between 110 and 120 Celsius degree. it can bring many advantages if you adopt the HDPE membrane to do the anti-seepage, such as good economic benefit, low comprehensive cost, less investment and coinciding the standard of sewage anti-seepage.