Particle Filtration for UV Units

Thus far in our discussion of ultra violet (UV) units we have looked at why UV units are necessary and at the importance of the UV dose received by the bacteria.  Of course, making sure the bacteria are actually hit by the UV light is a key element in the process and this is where particle filtration comes in.

All wells contain small specks of silt, sand, rock, hard water scale, precipitated metals, and other materials.  These tiny particles get draw up by the well pump with the water and sent on into the house where they will pass through your UV unit.  A particle with a diameter of just 10 um (one-tenth the thickness of a human hair) can shelter a bacterium from the UV light.  If the bacterium gets past the UV unit and into your plumbing, it is home free.

The solution is particle filtration.  MacLellan Water Technology installs a cartridge-style sediment prefilter immediately in front of all the UV units it installs.  Equipping this prefilter with a 5 um cartidge means it will screen out those 10 um and larger particles that are of concern.  The disposable cartridge should be changed once per year when you change your UV bulb (although, if your well throws a lot of sand, it can be changed more often to avoid pressure loss).

Some UV units come with tiny little prefilters.  Remember that, except for outside garden taps, all the water for your home is going to pass through the UV unit and therefore through this filter.  At minimum, MacLellan Water Technology uses a 20" by 2" cartridge size to ensure good water flow and pressure to your home.