How does a shower head 'increase water pressure by 200%'?

Maybe by forcing the water through a smaller opening, while maintaining the flow rate, which will increase the velocity of the water that makes it through. I have a showerhead with 3 different “pressure” settings, which simply blocks a part of the showerhead’s nozzles.

Yep, that’s how nozzles work.

Pressure is a function of force per amount of surface area. Reduce the surface area, and increase the pressure per surface area.

Same with rivers. The rapid areas are narrower.

Pressure does not increase, its velocity does

As mentioned above, by reducing the diameter of the holes the water comes out of, it increases the speed it exits.

Think of those twistable caps on a spray bottle. As you turn it clockwise, the opening narrows and the liquid emits from a fine mist to a laser-like stream, as you turn it.

Hmm, I wonder if it’s worth $35.00 to try it out.

My apt. building has low flow water. I recently spent $43 for a hand held shower head because standing under my old shower head was like standing in a light rain. The new one is much better. It was definitely worth it for me.

@Blackwater_Park Again, pressure means force per surface area, so pressure does increase when water pressure is focused.

Try adjusting a hose nozzle, and observe the water going from a moistening spray, to a shooting jet.

@Zaku @Blackwater_Park is correct. As area decreases, velocity increases but pressure decreases. Here’s a website that gives all the calculations For pressure AND velocity to increase would require something adding energy to the system…doing work on it. Typically, if the inside diameter of a pipe narrows down gradually, the velocity increases and the pressure decreases as it goes through the narrow part. Once the pipe widens out again, the exact opposite happens: the pressure increases and the velocity decreases. The situation is similar if an orifice is used (basically a partial blockage in the pipe.

The only way to increase pressure coming out of nozzle is if you use a venturi nozzle. In this design the piping narrows down, causing a lowering of pressure. The decreasing diameter then opens up immediately into a mixing chamber. In this chamber there is an inlet from another source that allows fluid to be “sucked” into the mixing chamber and carried through by the flow coming out of the nozzle. The resultant situation is that you have more material coming out of the venturi that you put in at the beginning, thus resulting in higher pressure at the outlet.

Fluid dynamics is rather unintuitive that way. Marketeers are definitely conflating velocity to pressure since that is what it feels like with these narrowed nozzle shower heads.