What does CALGreen require for plumbing fixtures?

CALGreen (the California Green Building Standards Code, Title 24 Part 11) sets mandatory maximum flow rates for every new residential plumbing fixture in an ADU. These limits are verified at plan check and at inspection — they are enforced code, not optional best practices.

Maximum fixture flow rates

Note that older 1.6 gpf toilets are no longer compliant with current California code, even though they are still sold elsewhere. If you reuse a fixture salvaged from a remodel or buy out of state, check the engraved flush rating before installing it. The same caution applies to showerheads and faucets, which are stamped with their GPM rating either on the body or in the packaging — the figure printed there must match what your fixture schedule promises.

How compliance is documented and verified

• On the plans: the plumbing fixture schedule must list each fixture's make/model and rated flow so the plan checker can confirm compliance at a glance.
• At inspection: inspectors may verify installed fixtures match the approved schedule, and some flag non-compliant showerheads or faucets at final.
• For showers with multiple heads: CALGreen generally limits the combined flow, so a rain head plus a body-spray array can quietly violate the rule even if each individual head is rated 1.8 GPM.

Beyond flow rates

CALGreen also requires hot water supply piping to be insulated (especially in unconditioned spaces) and limits the volume of water allowed to sit in the hot-water pipe between the heater and the farthest fixture, which can drive water-heater placement or a recirculation system. Low-flow fixtures also reduce the demand load on your water service, which can be the difference between tying into your existing meter and paying for a costly service upgrade — and many California water districts offer rebates for high-efficiency toilets you can stack onto an ADU project.

Flow-rate enforcement and local amendments vary by jurisdiction. Some water-stressed districts adopt stricter limits — confirm with your local building department and water utility.

Our plumbing plan sets specify CALGreen-compliant fixtures throughout and document the flow rates in the schedule. If you also need energy compliance, our Title 24 reports (a $240 add-on) coordinate water-heating efficiency with the rest of your MEP package.