We have hard water and terrible water pressure. This shower head is frankly a miracle. No idea how it works, but frankly don't care. Water pressure is phenomenal... when I turn on the shower a burst of air hits me in the face like I just turned on a plane jet. Water heats up in 3 seconds rather than a minute (not sure why that is other than maybe more water going through the pipes faster?). Learned not to ask questions... sometimes it is just better to believe in magic, and that is what this shower head delivers.