"It's not just the amount of water per faucet, but the amount of water per shower space."

Correct: Here's the rule:

"California does allow more than one showerhead to operate at the same time, but only under strict flow‑rate limits. If the combined flow of all simultaneously operating outlets exceeds 1.8 gallons per minute (GPM) at 80 psi, then the system must be designed so that only one outlet can run at a time."

Nearly all California-compatible shower heads have flow rates of 1.5, 1.75, and 1.8 gpm. Nearly all California-compatible hand showers have flow rates of 1.75 or 1.8 gpm. Even 1.5 + 1.75 >= 1.8 so you need a diverter to switch between the shower head and hand shower.

Most hand-held shower units attached to a shower head have a diverter, so only one head gets water at a time. It's like the thing that you pull to get the shower instead of the tub. One of the reasons this is standard is that the vast majority of showers don't have the flow to have both going at the same time because they come from one pipe.

I think that you are asking to have two completely different sets of controls in a single shower. That is, you want a fixed showerhead and handheld on one side of the shower and a separate handheld on the other side of the shower. That is not allowed in California (unless it's one of those "gang" style showers they had in my high school gym).

All showerheads within a shower need to be controlled by the same volume control and temperature control. A diverter is used to select the showerhead.

For example, see the attached photo of my primary shower (Samuel Heath controls with Hansgrohe showerheads). The top lever is the diverter. The center lever controls the volume (on/off), and the bottom lever controls temperature (thermostatic value). The wall-mounted fixed jet showerhead is on the opposite wall. And I have a rain head in the ceiling.

The second photo below shows my hall bathroom remodel (before waterproofing and tile). The copper pipes coming up from the floor bring hot and cold water to the brass shower valve in the center (combination of volume, thermostatic, and diverter control). The thermostatic valve mixes hot and cold water to the selected temperature and sends it to the selected output. This is a non-sharing valve from California Faucets.

The "nipple" on top will be replaced with a fixed showerhead. The "nipple" to the right of the shower valve will be replaced by an "elbow" that connects with a hose to a handheld.

If I were to add another set of pipes and valves on the opposite side of the shower, it would not meet California code. [Edited to add that I had to change the shower drain to a different brand as it was too close to the wall.]

You need a diverter in CA, as you can only run one shower head at a time in one shower.

Some people will pass the permitting inspections and then have things "fixed".

The only way that you can do what you want is to have a single diverter control all the water outputs inside the shower, or you create the space as two clear separate distinct showers. Meaning a partition between the areas. You can not have a single shower with multiple independently controlled water sources. This is also why drain size is controlled. Multiple water sources on at once will overwhelm a drain and lead to flooding.

I had to deal with CA code when we lived there, but I was glad to have more options when we built in FL.

No issues with multiple water sources in our shower in FL, or with the drain. Here we can have multiple water sources that are independently controlled. I like to add a volume control to each water source and not just an on/off control. I was also glad we didn't have to have the lowest volume toilets here in FL, so we get a decent single flush and you aren't forced to have to flush twice!

Hi, This is a true story of buracats in action.

I get a work order that a tenant's shower is cold. I drive out there and the unit is a tub shower.

I turn on the shower hot only and the water out of the shower is cold. I turn the valve from shower to tub, the water is hot. I take the shower head off and then run hot water to the shower, with no shower head the water is hot. I drilled out the holes in the shower head a little bigger, miracle hot water.

Good Luck Woodbutcher

" Hi, This is a true story of buracats in action. "

I have to disagree - this is a story of poor design and bad workmanship.

This is a classic issue of a long run from a water heater on one end of the house and a bathroom, usually the master bath on the other end. Often the supply lines are in the slab, and they aren't insulated or have minimal insulation. There's no return loop for a circulating pump. So, at 1.8 gpm, the heat is entirely disapated to the slab before it comes out of the shower.

The other possibility is a tankless water heater that has too high of a required flow rate to activate it or keep it running. Sometimes people set the temp on the tankless too high (no reason to do anything more than 120 - 125) so by the time it mixes down, there isn't enough flow through the heater to keep it activated.

Neither one of those issues should be blamed on buracrats.

@ wdccruise has the interpretation of code right. Inspectors are looking for the type of "creative reading" of the code you are suggesting. It's not worth having to redo the work.

California, like much of the west and south west, doesn't have enough water for people to be stupid about it. Same in Arizona, Colorado, New Mexico, Nevada, etc. If you really can't abide by reasonable water use codes, move to someplace that isn't a desert.

I realize that this thread was posted a few months ago ... but this weekend, for the first time, I saw a "double-shower" in a new construction home in SoCal. Apparently, this passed inspection. In the photo, it looks like mixed metals, but it was all consistent, just an illusion caused by reflected light.

Edited to add: there are two floor drains in this shower space, but no partition betwen the two showers, other than the built-in bench. Creatively, it is two doorless showers that are separated by a bench, and the controls for each shower are reachable from both inside and outside the showers.

coastal_vibe: "this weekend, for the first time, I saw a "double-shower" in a new construction home in SoCal."

The description of the bathroom states, "The primary bathroom includes a double shower designed for modesty as bathers will only view the tushies of their shower partners. The shower lacks a door to keep the shower cold and discourage unnecessary peeking. We added to the experience by placing the controls inconveniently as far from the opening and shower heads as possible. To maximize shower fun, we placed a useless box inside the shower to encourage sleepy bathers focus, lest they fall over the box and receive an unexpected wake up call."

@wdccruise:

Since you asked, this is the listing description of the primary bathroom that I referenced:

"... a spa-inspired bathroom boasting dual sinks, two separate standup showers with mid-spray jets, and a standalone soaking tub ..."

I shared the photo because it shows a creative way (two showers, facing each other) to meet the OP's wish list while adhering to local code for both safety and water conservation requirements. Local code requires that shower controls be accessible from both inside and outside the shower.

Privacy? In this bathroom, there is no door between the primary bedroom and en suite bathroom. There is a door on the WC and the WIC.

coastal_vibe: The brochure also states, "It'll be tushies up when you reach behind the freestanding bathtub to clean the floor and adjacent wall. You won't have any problem convincing children to bathe when they can throw their rubber duckies and other toys behind the tub and gleefully watch mommy scramble to retrieve them!"