I have that shower head too. ITS GREAT and yes there is a shut off knob on the bottom.. its that knurled piece you can see in the photo. I boondock for 6 months at a time and it makes the water go much farther but you still feel like you are getting a real shower.
2004 Chev Silverado Duramax optioned past the max. 2009 Jayco Eagle 308 RLS 765 watts of solar, 6-6 volt batteries (696 amp hour), 2000 watt (4000 surge) whole house inverter.
140 days boondocking in 2016
211/2015, 196/14, 247/13, 193/12