Please up vote on Product Hunt: https://www.producthunt.com/posts/shorter-shower

Longer version:

My brothers and I took after my father in a lot of ways. One of the biggest was taking very long showers. When I moved to California, it was frowned upon to take a long shower due to it wasting water. I tried to take shorter showers but I kept zoning out. All of a sudden, 5-10 mins went by and I hadn't done anything yet.

To solve this I tried setting timers, counting to myself, and a number of other ways. I realized the only way that I could consistently take a shorter shower is if something told me what I was supposed to be doing. That is when I created shorter shower. The app allows you to create activities (shampoo hair, wash body, etc) with an expected duration. You can combine the activities into multiple timers/routines. When you start the timer, it will change the volume of your phone to a predefined value so you can hear it over the shower noise. It will then audibly tell you what you should be doing when. It will stop the timer automatically when you are on the last activity and you turn off the shower. When the timer is done, the phone volume will be reset to its previous value. This app helped me go from 12 min showers to 5 min showers very quickly.

A few notes about data. Activity and timer data is stored on the phone. I send water usage metrics to a server but do not include user information. This is mainly to answer the question, how much water are people saving / using each day. I also use GA to track user interactions.