
Size
vs. Pressure
Mother nature
and physics provide some rules that apply to shower head pressure.
Every house has a given water supply pressure, and for any given
supply pressure (as a starting point) the resulting pressure
coming out of the shower head nozzles will decline with the
number of nozzles. Different types of nozzles can greatly affect
this, but if we are comparing shower heads with identical nozzles,
the shower head with the most nozzles will have the weakest
pressure and the shower head with the fewest nozzles will have
the most pressure. For example, it is guaranteed that in any
particular shower our 5 1/2" Classic will provide more
stream pressure than our 10" Classic, and our 6" Oasis
will provide more stream pressure than our 10" Oasis, simply
because the available pressure gets divided into fewer streams.
For this
reason we highly recommend choosing larger shower heads carefully
to ensure excellent nozzle quality to make the most of the available
supply pressure. Learn more
about Machined Cast Brass Nozzles

The machined cast brass nozzles of a "Classic" rain
shower head
(click for more info)