City water service entrance
What's wrong here?
- Static pressure is about 95 psi and no pressure-reducing valve is installed on the building side of the meter
- Static pressure must be held to 60 psi or less
- A thermal expansion tank must be installed at every water meter
- The bonding jumper around the meter is not allowed on potable water piping
Show the answer and the code reference
The answer
The gauge shows a static pressure of about 95 psi, over the 80 psi limit, and there is no pressure-reducing valve after the meter to bring it down.
Correct choice: 1. Static pressure is about 95 psi and no pressure-reducing valve is installed on the building side of the meter
UPC 608.2 requires an approved pressure regulator, preceded by a strainer, wherever static pressure in the water supply piping exceeds 80 psi, and the static pressure must be reduced to 80 psi or less. A test gauge on a drain valve with no water running reads static pressure, and here it reads about 95 psi. Pressure that high wears out faucet cartridges, toilet fill valves and appliance solenoids, bursts supply connectors, and adds water hammer. City pressure varies with elevation and distance from the pumping station, so put a gauge on every new service.
How to fix it
Install an approved pressure-reducing valve with a strainer (many have one built in) on the building side of the meter and its outlet valve, ahead of any branch, set it to 80 psi or less (50 to 60 psi is typical), and keep it accessible. Then add thermal expansion control at the water heater per UPC 608.3, because the regulator makes the system closed.
Code references
UPC 2018 608.2 — Excessive Water Pressure
Where static water pressure in the water supply piping exceeds 80 psi, an approved-type pressure regulator preceded by an adequate strainer must be installed and the static pressure reduced to 80 psi or less. The regulator and strainer must be accessible, and the regulator controls the pressure to the water outlets in the building unless the Authority Having Jurisdiction approves otherwise.
Drills citing 608.2UPC 2018 608.3 — Expansion Tanks, and Combination Temperature and Pressure-Relief Valves
A water system with a check valve, backflow preventer or other normally closed device that keeps building pressure from dissipating back into the water main must have an approved, listed, adequately sized expansion tank or other approved device to control thermal expansion, installed on the building side of that device.
Drills citing 608.3
Minnesota
Minnesota adopts the 2018 Uniform Plumbing Code with Minnesota amendments as the Minnesota Plumbing Code (Minn. Rules ch. 4714, effective Dec. 17, 2021). Search results indicate Minn. Rules 4714.0608 amends other parts of UPC 608 (the relief valve discharge rules in 608.5), but no Minnesota amendment to the 80 psi limit in 608.2 is known; check ch. 4714 before relying on it.
About the Minnesota Plumbing CodeWhy the other choices are wrong
- Static pressure must be held to 60 psi or less. UPC 608.2 sets the trigger at 80 psi. 50 to 60 psi is a common PRV setting, not a code maximum.
- A thermal expansion tank must be installed at every water meter. UPC 608.3 calls for expansion control where a check valve, backflow preventer or other normally closed device (a pressure regulator counts) keeps building pressure from bleeding back to the main. It is tied to that closed condition, not to the meter. Adding the PRV this service needs will very likely trigger it.
- The bonding jumper around the meter is not allowed on potable water piping. The jumper is an electrical-code item: the NEC does not let the grounding path to interior metal water piping rely on the water meter, so a jumper around the meter is standard. It does not affect the plumbing.