Custom Shower System Water Usage and Shower
Fittings' Flow Limits
This section applies to water usage of
a complete shower system. For more information about showerhead
flow limits and ways to correct low flow showerheads for higher
showerhead pressure, please see our related section under
Support
> Repair
Tips > Water
Pressure
Showerheads sold in most locations in North America are
required to have a flow limit of no more than 2.5 gallons
per minute (GPM) or 9.5 liters per minute (L/min) over a supply
water pressure range of between 20 and 80 pounds per square
inch (PSI). This limit has been legislated to save water and
energy. Manufacturers use either a flow restrictor or a flow
controller inserted into the showerhead to reduce the flow
to meet the 2.5 GPM (9.5 L/min) limit requirement.
Flow restrictors
Flow restrictors restrict flow by limiting the amount
of water entering into the showerhead or handshower with a
hole of a certain size. This generally restricts flow at lower
pressure to ensure the device does not exceed 2.5 GPM at the
top-end of the pressure range (80 PSI). Only very simple showerheads
use this type of restriction today.
Flow controllers
Flow controllers adjust the size of the hole to
the incoming water pressure to deliver 2.5 GPM or less over
a wide range of pressures. That means that if your house has
20 PSI or 40 or 80, you can expect to get the same amount
of water flow.
Increasing your house pressure with a pressure booster will
NOT substantially increase your "shower pressure"
(the force you feel coming out of the shower) through a flow
restricted or flow controlled showerhead. However, removing
the flow restrictor or flow controller
will increase your shower pressure by increasing the amount
of water flowing through the showerhead. If you have high
house pressure (60+ PSI), you will feel a big jump in shower
pressure. If you have low pressure (20 PSI), you may feel
a slight increase in shower pressure, but not much. In this
case, if you would like even more shower pressure, you can
add a pressure booster to gain shower pressure as long as
the rest of the shower system including the supply
pipes is properly plumbed.
Be aware that removing a flow restrictor or flow controller
will increase your water and energy consumption, and may increase
your utility bill. Keep the flow controller handy in case
you ever wish to replace it.
Flow capacity of showerheads with flow controller
As we mentioned earlier, almost all showerheads sold in
North America have their flow restricted to 2.5 gallons per
minute (9.5 liters per minute) maximum. Many people find this
satisfactory, even helpful, because water, energy and money
will be saved.
Flow capacity of showerheads without flow controller
Removing the flow restrictor or flow controller will increase
the amount of water that can flow through your showerhead.
If your house has adequarte pressure, and your valve can deliver
more water than the showerhead can use, then your flow rate
will be more than a showerhead with a flow restrictor or flow
controller. The exact amount depends on the contruction of
the showerhead and the dynamic pressure available to the showerhead.
Some manufactuirers will offer specification sheets of their
products with the flow restrictor or flow regulator removed.
Determining total water usage
If you plan on keeping flow regulation devides installed
in your showerheads and body sprays, then the amount of water
usage of your shower system is simply the total number of
devices you want to have running at the same time times 2.5
GPM. For example, a system with an overhead shower and 4 body
sprays would use 5 x 2.5 GPM or 12.5 GPM.
If flow regulation devices are removed, you need to determine
the water pressure you have
available and obtain water usage data from the showerhead
manufacturer. For instance, if you have 60 PSI available and
the showerhead runs at 4.2 while the body sprays run at 3.5,
then you calculate your usage as follows: (4.2 GPM x 1) +
(3.5 GPM x 4) = 16.2 GPM.
Use this information to help determine which mixing valve
you should use. For more accurate results consult each product’s
specification sheet.
Determine time to fill a tub
To determine the fill time for your tub, divide the capacity
of the tub in gallons by the flow rate of the valve at the
pressure available to the system in gallons per minute. The
result will be the number of minutes it will take to fill
your tub. (You can do the same with liters capacity and liters
per minute flow rate of the valve.)
capacity / flow rate = minutes to fill tub
For example: 100 gallon tub / 15 GPM valve flow rate = 6
minutes, 40 seconds |
