Multiple waterproof 4k cameras pointed at the inside of your shower from every angle and image recognition by some AI that detects when a naked person enters.

Don't forget to use Wifi and no firewall

You could use a classic dead man switch: Place several buttons around the whole place - basically everywhere except in the shower. Once you stop pressing any of these buttons for - let's say - 30 seconds you can assume you're taking a shower.

If you have a shower cubicle, could you put a door open sensor on it, and assume you're showering if the door is closed? I think it's normal to leave the doir open when not in use. It would probably also work if you had a shower curtain, so long as you always pulled it all the way closed in use.

Made a flowchart for you:

< Do you feel wet? >  
     |  
     +-- yes --> < are you indoors? >  
     |                |  
     |                +-- yes --> < are you wearing pants? >  
     |                |                      |  
     |                |                      +-- yes --> [ you peed yourself ]  
     |                |                      |  
     |                |                      +-- no --> [ you're taking a shower ]  
     |                |  
     |                +-- no --> [ it's raining ]  
     |  
     +-- no --> [ you are not taking a shower ]  

I would just go with special button, the most straightforward simple solution you have direct control over. Also sometimes you might need to use the shower without mood lights and then system based on humidity or water flow will just be annoyance.

If you use some tools when showering, like brush or spung, you can make a contact sensor into the hook/holder (more work, probably need a custom 3D print), but should also work and you don't need to press anything

I experimented with a humidity sensor in the shower and was surprised how quickly it spiked. It's how I woud do it. Other option would be a leak sensor in the basin but getting it to turn off at the right time would be very hard. You have a lot more control over this with a humidity sensor.

I'm using zwave for everything like this and wouldn't be at all concerned about battery for either scenario. Both would last years, much like my door and window sensors do.

Are u nekkid, but warm, and wet? You're in the shower.

Couple ideas, depending on what you have:

• When the warm water pipe heats up
• when the water heater starts drawing more power
• when the water meter detects warm water usage in the evening
• when the sound volume goes up in the bathroom
• when the weight sensors go off under the shower (or around it as you get in)
• when a movement sensor detects movement in the shower
• when a magnetic door sensor sees the shower curtains open
• when you press a (waterproof) button in the shower
• when a weight sensor under the shampoo holder detects less weight

How about a simple on off toggle inside your shower handle? Stupid simple and works anytime the waters turned on.

I use a humidity sensor, motion sensor and a helper that shows the change over a period of time. If the humidity raises fast (+2%/5m) and goes over a certain amount (unique, depending on your room's climate) the bathroom automation changes tracks to hold the light at 100%, turn the extractor fan on, and well, how you stop the automation depends on you. I let it stay on for 15 minutes before waiting for motion. Small tips: For me the humidity triggers the automation within 15s-1m of showering, which is okay for me. Motion sensors typically use IR to see movement. If the room is too steamy it might struggle to see you. Also, it cannot penetrate glass. It must have a line of sight to you.

The best alt I think would be mmwave presence sensors, but they're pricy and require a wired connection.

This is a fun question.

I have to assume the absolute ideal would be some sort of water flow detection right in line with the shower head. Likely hard wired. But like I said, that’s an ideal.

I think the other suggestions in the thread are reasonable. The microphone one seems most appealing to me since that could theoretically just occupy an outlet anywhere in the room.

I would use something like this to measure water usage in combination with an presence sensor in the shower stall. Water flowing + someone present in shower stall = someone taking a shower.

Flowmeter on the shower head or down in the supply lines to the tub/shower?

I'm using just humidity and its working great. I put the sensor away from my sink so it isn't triggered by washing my hands.

This will only consider you showering if humidity goes 9% above the 1hr average humidity:

You need a 'Statistics' Helper, call it "Average Bathroom Humidity" and base it on whatever humidity sensor you have. Make it "average linear" then set Max Age to 1 hour. (leave other options default)

Make this Template Binary Sensor called "Showering":

{{ (states('sensor.bathroom_sensor_humidity')|float - states('sensor.average_bathroom_humidity')|float) > 9 }}

@batshit I use a derivative of a humidity sensor, it works well enough and is really simple to set up.

Would a battery powered smart switch be an option?

Hit the switch and let HA do a command series.

@batshit Don't you notice getting wet? ;)Seriously though, couldn't you use a water leak sensor for this? Just make sure if it has a speaker to disconnect that, unless you like a loud beeping found when you shower.

Your individual shower habits might be predictable enough to if than your way to it with existing sensors.

If you track current draw on your boiler / water heater that would indicate a draw on hot water during time when you typically shower. You can add other checks for it to pass if you find too many false positives.

If you’re as glued to your phone as every one else alive atm a simple rfid / wireless charger or something you set your phone on when you strip for the shower triggering the event will likely be the most straight forward approach unless you bring your phone in the shower lol I’m occasionally guilty if the podcast is good enough 😅

Crossposted from showerthoughts

Vibration sensor that detects when water starts flowing through the shower head

Not sure if you have access to the pipes leading to the shower, but the droplet does what you're looking to do.

https://hydrificwater.com/

Any reason a flow sensor wouldn't work?

If you have a shower door: use a door/window sensor (on the outside). Trigger the mood light if the door was open for only a couple of seconds.

Still more complicated than hitting a switch, tho, IMHO.

The right way is some sort of inline water flow sensor, so it'll trigger within seconds of you turning on the shower to warm it up. With an esp32 and a sensor, and some clever use of the sleep function, it'd probably last a year or so on a couple of AA's.

Low effort and price tech is probably better in a wet environment though! If you just want the mood lighting, get a wireless button and stick it somewhere near. Tap it on, tap it off!

If you want to feel that automatic magic, consider a cheap battery powered temperature sensor. If you fix the chassis to the shower head pipe it'd probably be accurate enough. Also, assuming you need to wait for your shower to heat up, you'd have a pretty good idea when your shower was hot too - when it triggers your automation for the lights!

Just make sure the sensor polls often enough or can be made to report on a significant temperature difference in a timely fashion. Something like this might do it: https://sonoff.tech/products/sonoff-zigbee-temperature-and-humidity-sensor-snzb-02p

Also avoid WiFi for buttons, connection and addressing takes ages and sicks for an instant response needed for something like lighting changes

If it's an electric shower, you can do what a salamander pump does and add some detection wires on the shower box's on-switch. I appreciate you don't want wires around the shower but it's a fully direct "is the shower on" detector and the wires are technically in the shower rather than around it.

Motion sensor or light switch.

There are so many variables at play here.

I'd settle for the small lag with a humidity sensor. If you're the type to run the shower for a minute before getting in, it should kick in in that time.

Could do a presence sensor or motion sensor pointed at the shower. Haven't played with either, and you'd have to figure out water resistance.

I would go for a simple humidity sensor. You just need to do a bit of data collection first to get a baseline of "what taking a shower usually looks like" and then based on that create the automation.

The only problem with that is that depending on how accurate you want it to be, you may have to wait a while to take a few measurements until it triggers the automation.

For something like mood lights I would just use a ZigBee switch if I'm being honest though.

OK, assuming your switch is also smart

Option 1: long-press/double function turns on both light and fan, that triggers an "I am going to shower" 5 minute delay where a humidity sensor senses when it is over and keeps the fan on until humidity is stabilized with the rest of the house.

Option 2: get a smart flow meter instead of a smart valve. Then you have useful statistics for shower water usage in addition to an instantaneous status. This has the side effect of the mood lighting turning on "late"

Option 3: get one or make an esphome + LD2410S on battery or plugged in close by, nobody goes in the shower for more than like 10 seconds without showering

Option 4: Time of Flight sensor outside of the shower pointing in to tell when the door/curtain is closed. If the ToF sensor is (for example) between 1.1m and 1.2m, the door/curtain is closed

@batshit I have 2 humidity sensors: one inside the bathroom and one outside, to calculate the reference hum. point (to adjust triggering on rain or dry weather). I can adjust the speed of detecting by moving the hum sensor (cheap xiaomi ble) near the shower. It triggers in several seconds and turns on the exhaust fan.

sounds like you could use a clapper

Motion sensor positioned really close to the shower controls so it doesn't see anything but them/your hand moving.

The bigger question might be how do you turn it off? I like the vibration sensor on the shower head

@batshit so ein Quatsch