Traditional secondary water supply equipment, what are the hidden security problems

At present, many cities in the old neighborhood secondary water supply security risks are more serious, almost the old neighborhood water supply water quality are not up to standard, 7 layers of water pressure is not enough. At present, most of the solutions for the use of non-negative pressure water supply equipment or frequency conversion water supply equipment to change the secondary water supply renovation. Avoid insufficient water pressure and water quality is not up to standard and other issues.