Hi,
I’ve search a lot and I don’t event think its possible to do this.
I have a temperature sensor on a pipe so I can detect whether the hot water is on or off.
I want to know when I’m taking a shower.
I created a sensor thats is showing if i turn on the water or no. The problem is that not always I am turning on the hot water is to take a shower, maybe I’m just washing my hands. This only happens when hot water is turned on over 3 minutes (arbitrary value).
So how can I set homeassistant to change a past status to keep in in history.
It is no really a live-data so in some point I dont-know yet if this hot water turning on will convert in shower time, but I’d like to see in history when is started and when is over.
Try water leakage sensor in shower cabin. Just put it in some place that will ensure it gets wet but not submerged in water.
I use a humidity sensor in conjunction with the derivative sensor helper.
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Always good to search if others have had your same problem and fixed it 
HA cannot change past status, but you can rethink your logic by using what others have tried before you.
Here in this video you can see (although it’s in Spanish) how to create a derivative sensor to do what you want. I have it like this!
I already saw that video, (actually it gaves me the initial idea). I dont have a water tank but water heater instead. The aim of this project was triyng to reuse components I had at home. I was triyng to be more precise at the time of deciding when is turning to a shower. I also have a humidity sensor, so i will use it in conjunction to detect when is starting. Once I know that someone is taking a shower I can detect with temperature sensor whe it’s over