Yes, you must have your water tested prior to installing a UV systems. Many people feel that if they can fill a glass with water and the water looks clear then that must mean that it is. This is not true. There is more to water than what the naked eye can see. Water flowing through a UV system needs to be free from hardness, iron, turbidity, manganese and color (which can be called tannins). The following is what R-Can recommends for the Sterilight UV systems:
- Hardness < 7 gpg (grains per gallon)
- Iron < 0.3 ppm (parts per million)
- Manganese < 0.05 ppm
- Turbidity < 1 NTU
- UVT > 75%
- Tannins < 0.1 ppm
If these levels are exceeded scaling can occur, causing a decrease in the UV system's efficiency as well as an alarm condition if the system is monitored. We always recommend to our customers that they install a 5 micron filter prior to the UV in order to knock down any turbidity that may be present in the water.
Please see the following picture showing you what low water quality can do to your UV system (specifically iron staining on the quartz sleeve):
Courtesy of Dr. Jim Malley, University of New Hampshire
We do recommend that if you are drawing from a lake or from some other SURFACE water supply (lakes, rivers, dug well etc.) that a water analysis is ALWAYS done prior to the installation of a UV.