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P a g e
System Sizing
All UV systems are rated for a specific flow rate in water that meets the quality parameters on
page 5. PLEASE NOTE increasing the flow above the system rating or disinfecting water that does
not meet the quality parameters will decrease the dose and therefore compromise the microor-
ganism inactivation. To determine the flow rate, follow these simple steps:
1. Be sure no water is being used in the home.
2. Open a faucet or tap nearest the pressure system and run until the well pump starts.
3. Close the faucet and using a second hand watch, record the length of time in seconds until the
pump stops. This is known as the cycle time.
4. Then using a container of known volume, preferably in US Gallons, open the faucet or tap
nearest the pressure system and measure the amount of water drawn off until the pump starts
again. Depending on the size of the container used, it is acceptable to turn the faucet on and off
to empty the container. This measurement is known as the draw down.
To calculate the pressure system flow rate divide the draw down by the cycle time and multiply
that by 60.
Draw Down__________÷ Cycle Time____________ x 60=__________Pumping Rate in USGPM
Location
Choose a location where the main cold water line is accessible. The system must be installed
after other water treatment equipment (i.e. softener), but before any branches (See Figure 1).
Figure 1. Typical Installation
