The water that's consumed before you actually begin showering is called Warm-Up Waste and it’s made-up of both hot and cold water portions. Together those portions make-up about a quarter of your shower's total water use.
The first portion is the cold water that has to purge before the hot water can arrive. It's called Structural Waste. It lasts about one minute, its volume is about 1.5 - 2.5 gallons and it's made up of the previously hot, but now cold, water that was left in the pipes from your last shower. The presence of Structural Waste requires you to turn-on the shower and let it run for a minute or so before your shower becomes warm and ready.
But during the Warm-Up Waste period, a great deal of hot water is innocently wasted also. It's called Behavioral Waste and it occurs when you, just like everyone else, use your time comfortably and efficiently while waiting for your shower to get warm. Think of Behavioral Waste as the amount of time you accidentally spend away from the shower after your hot water has arrived, but before you get in. After all, you're waiting for the shower to get warm and are off brushing your teeth, making the bed, picking out clothes … and you need to finish that task before returning to the shower. As a result, it's normal for about 1.5 - 2.5 gallons of hot water to accidentally run down the drain while you're away.
“Behavioral waste occurs when bathers use their time comfortably and efficiently while waiting for hot water to reach the shower. Activities include brushing teeth, using the toilet, picking out clothes, drinking coffee …”
According to numerous studies, the typical shower lasts about 8 minutes See the report data
Analysis of recent data collected, in independent studies, by researchers such as Lawrence Berkeley National Lab, Greystar and major utility companies indicates Behavioral Waste comprises about 45-60 seconds of every shower.
Consider that another minute of your total shower time is Structural Waste and that means 16% of your shower's hot water is wasted before you ever get in.
“In general, it appears as if the desire by users to multitask as part of their shower warm-up routine is strong and established habits may be difficult to break regardless of how quickly hot water arrives at the point-of-use.”
Evolve's ShowerStart technology, either in a tub/shower combo or a stand alone shower option, eliminates Behavioral Waste without asking you to change your warm-up routine. In fact, most users report that the technology greatly improves user comfort and convenience.
How it works: As the hot water reaches the shower, flow will slow to a trickle. This trickle is just enough to let you know your shower is ready and waiting. When you return, simply activate the shower head by pulling the cord to resume normal flow.