How does Phoenix size a water meter for a new building?

The Water Meter Sizing Guideline, TRT 00142, is a joint Planning & Development and Water Services document, revised 08/26 and tied to UPC 610.1, IPC 604.1 and IRC P2903.1 in the 2024 codes. Its policy opens with "Water meters shall be sized in accordance with the following table." The table lists, for each meter, a maximum flow in gallons per minute and a maximum number of fixture units. The rule for a design that doesn't fit: "Project designs which exceed the listed gpm unit values must be upsized to the next larger meter."

The note on the two largest sizes says the IPC design method is limited to 593 gpm.

The other parts of the guideline, in short:

• Fire flow vs fixture units. "Select the larger meter when comparing meters based on fire flow to ones based on fixture units." The gpm column is used for fire sprinkler or domestic demand.
• Minimum tap. New service taps for buildings, including single-family lots, are at least 1 inch. New 3/4-inch taps are for landscape irrigation or other approved special uses only.
• Existing 3/4-inch service. Existing 3/4-inch taps and meters may stay as long as they meet the fixture unit limit in the table.
• Big meters. Meters 6 inches and larger need advance consultation with Water Services on availability, cost and delivery. Turbine meters are case by case.
• Main limits. A new service connection is limited to 50% of the service main's diameter.
• No combination meters. Fire, domestic and landscape demands each get their own service connection, except that a combined fire and domestic meter is allowed for a single-family home on a single lot.

• Fixture unit (FU): a load value the plumbing code assigns to each fixture. You add them up for the building and compare the total to the column for your code and fixture type.
• Flush tank vs flush valve: column 3 is for buildings where toilets and urinals are mostly tank type; column 4 is for mostly flushometer (flush valve) type. Flush valves draw a lot of water fast, which is why their limits are lower on small meters.
• Compound meter: a meter built to read both low and high flows, listed for the 3-inch and larger sizes.
• Tap: the connection to the city main. The guideline treats tap size and meter size separately, and it bases fees on the meter.

Anyone sizing a new Phoenix meter or asking for a bigger one: architects and engineers on commercial and multifamily jobs, contractors on tenant improvements that add fixtures, and owners of houses on a new lot. It also matters when a business adds restrooms or a kitchen and the existing meter's fixture unit limit gets crossed.

This does not apply to a property served by another water provider, or to private submeters downstream of the city meter. It also does not decide backflow, which comes from City Code Chapter 37.

• A café moves into a strip center suite. The plans add a hand sink, a three-compartment sink and two tank toilets. The engineer totals the fixture units under the code the plans use (UPC or IPC) and checks the 1-inch row. Under the limit, the meter stays.
• A medical office uses flushometers. The same fixture count that fit a 1-inch meter with tank toilets may not fit with flush valves, because the flush valve column for 1 inch is 48 UPC or 50 IPC. The answer flips to a 1-1/2 inch meter.
• An older home on 3/4-inch service gets a casita. If the added fixtures push the total past 30 UPC flush tank units, the meter has to be upsized, and the new meter size sets the development fees.

1. 1Count fixture units for the whole building under the code your plans follow, UPC or IPC/IRC, and note whether toilets are mostly tank or flush valve.
2. 2Find the gpm demand, including any fire sprinkler demand, and pick the larger meter of the two methods.
3. 3Check the table in TRT 00142 and move up a size if any limit is exceeded.
4. 4For meter sales, tap and service fees, contact the Planning & Development Engineering Counter at (602) 262-6551, as the guideline directs.
5. 5For impact fee estimates, email impactfees@phoenix.gov or call the Impact Fee Manager at (602) 495-5455.
6. 6For 6-inch and larger meters, start the Water Services consultation early.

• "Fees follow the tap size." The guideline says impact fees, WRA and DOF "are based on the water meter size, not the tap size."
• "A 3/4-inch meter is fine for a small office." Not with flush valve toilets: the table gives 3/4-inch meters 0 flush valve units.
• "One meter can serve the fire line and the building." Combination fire, domestic and landscape meters are prohibited; only a single-family home on a single lot may combine fire and domestic.
• "New homes can still get a 3/4-inch tap." New building taps start at 1 inch; 3/4-inch is for irrigation or approved special uses.
• "Any size reducer works." The Water Services design manual says a service connection "can only be reduced one size," for example 2-inch to 1.5-inch.