3.3 Water Conservation, Faucets, and Fittings

Water Conservation and Flow Rates

Water conservation requirements are a central focus of the International Plumbing Code (IPC). The maximum allowable flow rates and water consumption limits for plumbing fixtures are established in IPC Table 604.4. These limits ensure that commercial facilities operate efficiently without wasting potable water resources.

Key Flow and Consumption Limits

• Water Closets: Both gravity tank and flushometer-type toilets are restricted to a maximum consumption of 1.6 gallons per flush (gpf). This standard applies to floor-mounted and wall-hung water closets. While older systems consumed 3.5 to 5.0 gpf, modern commercial codes enforce this conservation limit to reduce municipal sewer loads.
• Urinals: The maximum water consumption is 0.5 gpf. Urinals flushing at the old standard of 1.0 gpf are prohibited in new installations. Nonwater (waterless) urinals are permitted when approved by the local authority, provided they comply with ANSI/ASME standards and are equipped with a liquid-barrier trap seal to prevent sewer gas leakage.
• Public Lavatory Faucets: Faucets in public restrooms (e.g., offices, hotels, airports, schools) are limited to a maximum flow rate of 0.5 gallons per minute (gpm) at a test pressure of 60 psi.
• Private Lavatory Faucets: Faucets in private settings (e.g., residential dwellings, private office bathrooms, individual hotel guestrooms) are allowed a maximum flow rate of 2.2 gpm at 60 psi.
• Private Kitchen Faucets: Restricted to a maximum flow rate of 2.2 gpm at 60 psi.
• Showerheads: Restricted to a maximum flow rate of 2.5 gpm at 80 psi. This limit applies to the total cumulative discharge of all showerheads and body sprays that can operate simultaneously within a single shower compartment.

Metering Faucets

In public restrooms, self-closing or metering faucets are frequently used. A metering faucet is designed to deliver a specific volume of water and then shut off automatically. Under Table 604.4, metering faucets are restricted to a maximum of 0.25 gallons of water per cycle. The user initiates the flow (e.g., by pressing a button or triggering a sensor), and the valve closes automatically after delivering the pre-set volume.

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Sizing and Pressures for Flushometer Valves

Flushometer valves (flushometers) require a substantial, rapid flow of water to operate because they do not rely on the storage capacity of a gravity tank. Sizing the supply piping correctly is a major inspection point:

• Diaphragm vs. Piston Valves: Flushometer valves operate on a pressure differential. Diaphragm-type valves use a flexible rubber diaphragm with a small bypass orifice, while piston-type valves use a metal piston. A blockage in the bypass orifice is the most common cause of a valve failing to shut off, leading to water waste.
• Minimum Supply Pressure: Per IPC Table 604.3, a flushometer-type water closet requires a minimum flow pressure of 20 psi at the fixture. A flushometer-type urinal requires a minimum of 15 psi. If the building supply pressure drops below these values, the flushometers will fail to clear the bowl and reset.
• Minimum Pipe Sizing: Per Table 604.5, the minimum water supply branch line size for a flushometer water closet is 1 inch. A flushometer urinal requires a minimum branch size of 3/4 inch. Sizing these supply lines too small will cause inadequate flushing and operational failure.

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Scald Prevention and Temperature Limits

To prevent thermal shock and severe scalding, the IPC mandates automatic mixing valves for bathing and public hand-washing facilities. Plain two-handle valves (lacking automatic pressure or temperature balancing) are strictly prohibited for these uses.

Shower and Tub/Shower Valves

• Required Valve Type: Shower control valves must be of the pressure-balancing, thermostatic, or combination pressure-balancing/thermostatic type, complying with ASSE 1016 or ASME A112.18.1 (IPC Section 424.3).
  • Pressure-Balancing Valves: These valves use a sliding piston or diaphragm to balance cold and hot inlet pressures. If the cold water pressure drops (e.g., someone flushes a nearby toilet), the valve automatically reduces the hot water flow to prevent scalding.
  • Thermostatic Valves: These valves react directly to temperature changes using a wax element or bimetallic coil to adjust flow.
• Maximum Shower Temperature: The control valve must feature a high-limit stop that prevents the user from adjusting the hot water discharge temperature above 120°F. This limit must be field-adjusted by the installer during inspection using a thermometer.
• Bathtub and Whirlpool Valves: The water delivered to a bathtub must be limited to a maximum temperature of 120°F by an approved tempering device complying with ASSE 1070 or ASSE 1016.

Public Hand-Washing Tempered Water

• Temperature Limit: Tempered water delivered to public hand-washing facilities (sinks in public restrooms) must be limited to a maximum temperature of 110°F (IPC Section 607.1.2).
• Required Device: The temperature must be controlled by an approved thermostatic mixing valve complying with ASSE 1070 (often installed under the sink basin).
• ASSE 1070 vs. ASSE 1017: ASSE 1070 covers point-of-use mixing valves. ASSE 1017 covers master mixing valves at the water source. An ASSE 1017 valve is not an acceptable substitute for an ASSE 1070 valve at a public lavatory, because it does not protect against pressure fluctuations inside the branch piping.

Hot Water Recirculation Sizing (Section 607.2)

To conserve water that would otherwise run down the drain while waiting for hot water, the IPC requires a hot water circulation system or heat trace system when the developed length of hot water piping from the source (e.g., water heater) to the furthest fixture exceeds 50 feet. Sizing must be based on the developed length along the pipe path, not straight-line distance. The system must include controls (timers or temperature sensors) to shut off the pump when there is no demand, satisfying energy codes.