Per, Georgia Environmental Protection Division which has regulatory control of all public water systems in the state:
MINIMUM STANDARDS FOR
PUBLIC WATER SYSTEMS
May, 2000
Drinking Water Permitting & Engineering Program Georgia Environmental Protection Division 205 Butler Street, S.E.
Floyd Towers East, Suite # 1362
Atlanta, Georgia 30334
7.1.1 f. “The system must be designed to maintain a minimum pressure of 20 psi at each service connection and at all points in distribution system under all conditions of flow. The normal working pressure in the distribution system should be approximately 60 psi and not less than 35 psi.”
7.1.1 g. “Wide variations in pressure above the minimum requirement of 20 psi may be inherent in the design of a distribution system but pressures no greater than 100 psi should be delivered to the customer (unless higher pressures are requested.) The 100 psi maximum pressures can be met by pressure reducing valves in vicinity of each customer's source line, or by designing the distribution system to limit the maximum pressure.”
I recommend that you call the Georgia Environmental Protection Division and get them involved. Also, contact the Board of Professional Engineers, and get them involved. This is a matter of gross negligence on the part of the Engineer who designed the system.
The system is responsible for the cost of the pressure reduction, not you. Send them the bill, and see what happens.
All the states have very similar regulations, because the federal clean water act, gave the EPA, jurisdiction over water systems, and gave them the authority to delegate that authority to the States, if the State has regulation and monitoring equal or more stringent than the EPA regulations.
So the above requirements are the EPA direction, and are the standard nearly everywhere in the nation.