The consumer should prepay the water before using. One family with one meter to record the water quantity. Value will shut down for warning when the remaning water is less than the warning limitation , and the valve will open up when inserting the card. Value will shut down when water is used up , then the consumer has to purchase water again. Valve will termly shut down and open up automatically to prevent rust. Detailed LCD display.Low consumption design .The data will be saved even if the power is cut. Battery life is more than 5 years .Low battery warning. Patent ball valve .Low pressure loss. There are cold water meter, hot water meter, purified water meter etc. in our products.