The principle of 2-steps hyperfiltration device is to adjust the PH-value of waterthrough first grade device,then let second step high pressure pump transter liquid into the second step hyperfil system to treat and get the cleaned water at last.The desalt ratio of the 1-step hyperfiltration system is over 99.5%.It needn't floe through the way of direct exchange treatment and it can be up to the standards of bottled drinking water(Conform to GB17323-1998).