3.3 Water Closets, Urinals, Lavatories, Sinks, and Flush Devices

Flow rates and flush volumes — IPC Table 604.4

Section 401.3 sends every fixture and fitting to Table 604.4 for maximum water use. These seven rows are worth memorizing outright:

Two footnotes: a hand-held shower spray is a shower head (so it carries the 2.5 gpm limit), and consumption tolerances come from the referenced standards.

The pressure reference changes with the fixture — 80 psi for shower heads, 60 psi for lavatory and sink faucets. That difference shows up in exam distractors.

Water closets — Section 425

IPC 401.2 prohibits water closets having a concealed trap seal, an unventilated space, or walls not thoroughly washed at each discharge, and prohibits any water closet that permits siphonage of the bowl contents back into the tank. Trough urinals are prohibited outright.

Remember the companion drainage rule from IPC 704.2: a 4-inch by 3-inch closet flange, a closet bend with a 4-inch inlet and 3-inch outlet (4-inch leg upright and below), and an offset closet flange are not considered reductions in size in the direction of flow.

Flushing devices — Section 415

• 415.1 Every water closet, urinal, and similar fixture must be provided with a flushing device, and 415.1.1 requires a separate flushing device for each fixture.
• 415.2 Flushometer valves and tanks conform to ASSE 1037/ASME A112.1037/CSA B125.37.
• 415.3.1 Fill valves conform to ASSE 1002/ASME A112.1002/CSA B125.12 or CSA B125.3, with the fill valve backflow preventer located not less than 1 inch above the full opening of the overflow pipe.
• 415.3.2 Overflows in flush tanks shall discharge to the water closet or urinal connected to the tank, and shall be sized to prevent flooding the tank at the maximum rate at which the tank is supplied with water under the manufacturer's design conditions. The overflow pipe opening shall be located above the flood level rim of the water closet or urinal, or above a secondary overflow in the tank.
• 415.3.4 Access is required to flush tank interiors.

Urinals — Section 424

Beyond the 1.0-gallon limit and the 67/50 percent substitution rule from 424.2, urinals are governed by 405.3.5 partitions (30 inches apart, 12 inches up from the floor, 60 inches high, 18 inches out or 6 inches past the lip) and by the 15-inch centerline and 21-inch front clearances of 405.3.1. Table 709.1 gives a nonwater-supplied urinal a drainage fixture unit value of 1/2, against 2 dfu for a urinal of 1 gallon per flush or less and 4 dfu for any other urinal.

Lavatories — Section 419

"Tempered water" is defined in the code as water ranging in temperature from 85 degrees F to 110 degrees F.

Sinks, dishwashers and food waste disposers

• IPC 422.2: sink waste outlets not less than 1-1/2 inches, with a strainer or crossbar restricting the clear opening.
• IPC 416.2: domestic food waste disposers shall be connected to a drain not less than 1-1/2 inches in diameter.
• IPC 416.3: commercial food waste disposers shall be connected to a drain not less than 1-1/2 inches in diameter, and shall be connected and trapped separately from any other fixtures or sink compartments.
• IPC 416.4: food waste disposers shall be provided with a supply of cold water, protected against backflow by an air gap or backflow preventer in accordance with Section 608.
• IPC 409.4: a residential dishwasher waste connection shall connect directly to a wye branch fitting on the tailpiece of the kitchen sink, directly to the dishwasher connection of a food waste disposer, or through an air break to a standpipe. The waste line shall rise and be securely fastened to the underside of the sink rim or countertop.
• IPC 409.2: dishwashing machines require backflow protection per Section 608.

Bathtubs, bidets and specialty fixtures

• IPC 407.2: bathtub waste outlets not less than 1-1/2 inches; overflows conform to the same standards.
• IPC 408.3: bidet water temperature is limited to not greater than 110 degrees F by a water-temperature-limiting device conforming to ASSE 1070.
• IPC 423.1: baptisteries, ornamental and lily pools, aquariums, fountain basins and swimming pools with water supplies must be protected against backflow per Section 608.
• IPC 423.3: pedicure chairs with an integral foot bathtub, and footbaths, are limited to not greater than 120 degrees F.
• IPC 412.10: head shampoo sink faucets are limited to not more than 120 degrees F and must have integral check valves preventing crossover between hot and cold.

Drinking fountains — Section 410

• 410.3.1: where drinking fountains are provided on an exterior site, a floor, or within a secured area, not fewer than two must be provided — one for people who use a wheelchair and one for standing persons. A single fountain with two separate spouts meeting both may substitute.
• 410.3.2: where more than the minimum is provided, 50 percent must serve wheelchair users and 50 percent standing persons.
• 410.4: where a restaurant provides drinking water in a container free of charge, drinking fountains are not required there. In other occupancies where three or more fountains are required, water dispensers may substitute for not more than 50 percent.
• 410.5: drinking fountains, water coolers and water dispensers shall not be installed in public restrooms.

Colorado field note (not exam-scored): Board Rule 1.2(E)(1)(u) broadens 410.4 to cover restaurants and A-2 occupancies, and Rule 1.2(E)(1)(nn) adds section 802.1.8 expressly allowing a domestic dishwasher to connect to a separately trapped standpipe with an air break or air gap.

Floor and trench drains — Section 413

Pair 413.3 with the rodentproofing rule in IPC 304.2 — strainer plate openings not greater than 1/2 inch in least dimension — and with the trap-seal protection requirements of Chapter 14 of this guide.