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

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

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 ]  

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.

Without trying something similar yet, here are some ideas:

• motion sensor on top of your shower
• trying to detect the vibration of the water flow
• a simple switch that you hit before you get into the shower

Also think of other times you "use" the shower, like cleaning it. Some methods will also be triggered then.

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.

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.

I bet you can rig up something microphone-based, there's tons of software nowadays for analyzing audio, and you don't need to run the analyzing software on the device with the microphone anyway. Though the analyzing would likely take a little bit longer that you'd want it to.

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

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.

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 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.

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

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/

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.

Would a battery powered smart switch be an option?

Hit the switch and let HA do a command series.

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.

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.

Crossposted from showerthoughts

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 😅

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

mmwave sensor, humidity sensor, and/or monitoring your water heater power usage. any of those 2 should work.

I am actively working on a bunch of ML algorithms for home assistant for exactly this type of thing, detecting 'activity' per room.

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