Under the UPC's alternate water source provisions, how may a gray water system be connected to the building's potable water supply?
Not quite. The answer is D: It may not be directly connected; potable makeup water to a non-pressurized storage tank is allowed only through an air gap
Gray water systems may have no direct connection to the potable supply (or to treated nonpotable or reclaimed water systems). The one allowance is makeup water for a non-pressurized storage tank, and then only through an air gap. Check valves and dual-check assemblies are not accepted substitutes, and filtering does not change that — this is a cross-connection rule, not a water-quality one.
Reference: UPC 2021 §1503.3 (Gray water — connections to potable and reclaimed water systems)
Checked against the official text
Checked against the 2021 UPC text. Washington's exam is written against the 2015 edition, which we have not read for this section, so confirm it against your 2015 book.
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