CALGreen 5.305 says 'Reserved.' The 2028 draft fills it with a rule

Section 5.305 is blank today

Open the 2025 CALGreen and turn to Section 5.305, Water Reuse Systems. You'll find one word: (Reserved). No requirement, no options — a placeholder the state left itself room to fill.

Verified against the 2025 CALGreen text: Section 5.305 reads "WATER REUSE SYSTEMS" followed by "(RESERVED)." Nothing more.

Here's the thing: the state is now drafting what goes in that blank. A staff draft dated September 3, 2026 — released for SB 745 Nonresidential Workshop #4 — writes a rule into 5.305 for the first time. It is a draft, not adopted code, and it can still change. But it's the clearest look yet at what new commercial, institutional, and industrial buildings will have to do.

The rule: pick one option

Draft Section 5.305.1 is short. It would say: "Newly constructed nonresidential buildings shall comply with one option in either Section 5.305.2 or Section 5.305.3." One option. Not all of them — one.

That structure matters. The draft pulls a set of measures that today live in the voluntary Appendix A5 up into the mandatory code, then lets the project team pick the pathway that fits the site.

Indoor options (5.305.2):

• Nonwater urinals — where four or more urinals are provided across the project, all urinals must be nonwater. (The prior draft set that trigger at ten; this one lowers it to four.)
• Indoor recycled water — dual-plumb for potable and recycled where municipal disinfected tertiary recycled water is available to the site, or preplumb where it's coming.
• On-site treated nonpotable water for indoor use, or preplumbing for a future system.

Outdoor options (5.305.3):

• Recycled-water irrigation
• Rainwater catchment
• On-site treated nonpotable irrigation
• A simple or complex gray water system

Verified against the draft (5.305.2.1): "Where four or more urinals are provided throughout the project, all urinals shall be nonwater urinals complying with Section 412.0 of the California Plumbing Code."

Three ways out

The draft carries three exceptions:

1. Your water is already reuse. If the public water system serving the project draws on an indirect or direct potable reuse project, 5.305 doesn't apply.
2. Nothing is feasible. If the design team demonstrates every option is not feasible and the authority having jurisdiction approves, none is required. The draft lists example reasons — including costs exceeding 10% of total project cost.
3. Local code already requires it. If a locally adopted standard already mandates one of these systems, 5.305 asks for nothing more.

That 10% figure is live. The draft says the Commission is seeking input on it and notes 5% was suggested in comments on the previous draft. If you build nonresidential in California, that threshold is worth an opinion — a lower number makes the feasibility off-ramp harder to reach.

What goes away

The draft also deletes the voluntary 12%, 20%, and 25% indoor water-savings targets from Appendix A5. The stated logic: fixture baselines have already dropped so far that wringing out another percentage isn't practical, and the real reduction now lives in mandatory 5.305.

In their place, Tier 1 and Tier 2 projects would face size-based reuse prerequisites. For example, a project of 10,000 to under 40,000 square feet with bathrooms or clothes-washer hookups would have to choose the gray water option specifically. Larger size bands get their own prerequisites.

If you've been tracking the current-code water worksheet, this is the same water-efficiency corner of CALGreen — but the direction of travel runs from voluntary percentage math toward a mandatory install-something rule.

Why it matters now

This traces back to statute. SB 745, the Drought-Resistant Buildings Act (Cortese, Statutes of 2023), added Health and Safety Code §18940.7, which directs the Building Standards Commission to develop standards that reduce potable water use in new nonresidential buildings — explicitly including "consideration of requiring installation of water reuse systems" and preplumbing. Draft 5.305 is that direction taking shape.

The timing: the 2028 code from this cycle takes effect January 1, 2029, with the formal 45-day public comment periods falling inside the July–October 2027 public-review window. So a building headed for a 2029-or-later permit should plan around this menu now — and anyone with a view on the 10% threshold can weigh in before that formal window opens.

Two cautions. This draft is nonresidential only — the residential side runs on a separate statutory track. And it's a staff draft whose internal cross-references are still being cleaned up, so confirm the current draft text and any local requirements with your AHJ before you design to it.

What CrossBeam does with it

CrossBeam watches the code that isn't final yet, not just the code on the books — so when a "Reserved" section starts filling in, you hear what's coming while there's still time to comment or budget for it. When 5.305 lands, a nonresidential water-reuse check gets measured against the option the project actually chose.