7.4 Nonpotable Water Systems, Identification, and Reclaimed Water

Why identification is a safety system

Every other rule in Chapter 7 of this guide prevents nonpotable water from entering the potable system. Identification prevents the opposite failure: a future plumber, maintenance technician or homeowner mistaking a nonpotable line for a potable one and tapping it. Buildings outlive the people who built them, so the marking has to survive.

Signage at outlets — IPC 608.9.1

Nonpotable water outlets, such as hose connections, open-ended pipes and faucets, shall be identified with signage that reads: "Nonpotable water is utilized for [application name]. CAUTION: NONPOTABLE WATER - DO NOT DRINK."

Requirements for the sign:

• Words legibly and indelibly printed on a tag or sign of corrosion-resistant waterproof material, or indelibly printed on the fixture.
• Letters not less than 0.5 inch in height.
• Colors in contrast to the background.
• In addition to the wording, the pictograph in Figure 608.9.1 ("do not drink") must appear.

Pipe labeling and marking — IPC 608.9.2

608.9.2.1 Color: the identification color must be discernible and consistent throughout the building, and purple identifies reclaimed, rain and graywater distribution systems.

608.9.2.2 Lettering size scales with pipe diameter, per Table 608.9.2.2:

Nonpotable water systems — IPC Chapter 13

Chapter 13 covers nonpotable water systems generally: graywater, rainwater, reclaimed water and on-site treated nonpotable water. Colorado adopts IPC Chapters 2 through 13, so Chapter 13 is part of the Colorado Plumbing Code.

Core rules:

• 1301.2.2 Filtration: nonpotable water used for water closet and urinal flushing applications shall be filtered by a 100-micron or finer filter.
• 1301.3 Identification: nonpotable distribution piping is identified per 608.9.2.
• 1301.4 Materials: nonpotable piping conforms to the material tables for the application.
• Storage tanks must be covered, labeled, and protected from contamination, with overflows and drains that cannot cross-connect.
• Makeup water to a nonpotable storage tank from the potable system must be protected by an air gap — never a mechanical device on an open tank.

IPC 608.12 Potable water tanks requires potable tanks to be enclosed and covered; 608.4 requires overflow, relief valve and waste discharge pipes from pumps, filters, softeners and tanks handling potable water to terminate through an air gap.

Definitions that matter

• Graywater (IPC 202): waste discharged from lavatories, bathtubs, showers, clothes washers and laundry trays. It excludes water closet, urinal, kitchen sink, dishwasher and utility sink waste.
• Reclaimed water: nonpotable water that has been derived from the treatment of wastewater by a facility or system duly authorized by the authority having jurisdiction.
• Blackwater: waste containing bodily or other biological wastes, as from water closets, urinals, kitchen sinks, dishwashers and utility sinks.

Colorado field note (not exam-scored): Colorado rewrites both definitions. Board Rule 1.2(E)(1)(f) defines graywater as wastewater collected from bathroom and laundry room sinks, bathtubs, showers and laundry machines for beneficial use, excluding toilets, urinals, kitchen sinks, dishwashers and non-laundry utility sinks. Rule 1.2(E)(1)(g) defines reclaimed water as domestic wastewater that has received secondary treatment by a domestic wastewater treatment works plus additional treatment sufficient to meet the standards for approved uses.

Colorado also modifies the filtration exception (Rule 1.2(E)(1)(yy)): reclaimed water sources are not required to meet the 100-micron filtration requirement, and graywater treatment systems installed per Section 1302.6.1 do not need additional filtration. Rule 1.2(E)(1)(aaa) adds a required sign on the door of any room containing graywater treatment works: "CAUTION GRAYWATER TREATMENT WORKS, DO NOT DRINK, DO NOT CONNECT TO THE POTABLE DRINKING WATER SYSTEM. NOTICE: CONTACT BUILDING MANAGEMENT BEFORE PERFORMING ANY WORK ON THIS WATER SYSTEM."

Reuse rules — IPC 608.10 and 608.11

608.10 Reutilization prohibited: water used for cooling equipment or other processes shall not be returned to the potable water system. Such water may be reused for:

• flushing water closets and urinals, or
• irrigation,

provided that it is not sprayed onto areas open to public use — the spray restriction exists because aerosolized nonpotable water is an inhalation route.

608.11 Reuse of piping: piping that has conveyed nonpotable water or other contaminating substances shall not be reused for potable water service or distribution. Reusing an old irrigation main as a domestic water line is prohibited no matter how thoroughly it is flushed.

Putting the chapter together: an inspection walkthrough

A commercial building uses reclaimed water for water closet and urinal flushing and for site irrigation.