Idea of Shower Icon
It's a picture of a shower head with black dots underneath it. Right under the head part there are 3 black dots and then underneath that is 4 black dots and underneath that is 5 black dots making it look like water coming ou like a shower is on.
This page shows the different variations of the Shower from an Icons8 icon pack. Feel free to resize and recolor the icon, and then download the icon in PNG format for free.