Ultraviolet - UV Water Purification Systems
Did you know: UV systems can destroy 99.99% of harmful
microorganisms without adding chemicals or changing your water’s
taste or odor?! It is one of the four methods of disinfection approved by the United States FDA. UV has proven to be a quick, reliable and cost effective method of disinfecting water for both point of use and point of entry.
Ultraviolet (UV) is a safe, clean, easy-to-maintain
method of assuring that water is free of bacteria. UV Water Purification
uses Ultraviolet light, just like sunlight, to kill micro-organisms
that may be in the water. It is a proven technology that has no
significant drawbacks. In some applications, its initial cost
is a bit more than chlorination, but because of its low operating
cost, it quickly pays for itself. It is environmentally friendly
and essentially trouble-free. Most ultraviolet water treatment
systems require only an annual change of lamp – as simple as changing
a light bulb – and a periodic change of the filter
ESP offers premier brands of UV systems and replacement bulbs, lamps and components for a wide variety of UV systems.
UV Water Purification
There are over 19 million American households and
cottages that rely on private wells. Tens of thousands more rely
on lakes, streams and other surface water sources. Unfortunately,
not all of them have a UV water purification system protecting
them from harmful microorganisms.
While a nation-wide study does not exist, smaller
scale studies have commonly found that 40% of wells in any given
region suffer from E. coli and/or coliform bacteria at any given
time not to mention the countless other microorganisms that may
be in a water supply.
The quality of well water can vary from day to day
and from year to year in the short term, things like heavy rainfalls
or snow melt can affect water quality. In the long term quality
may be affected by distant contamination sources such as earthquakes,
and other factors. Water that has been safe for years will not
necessarily be safe tomorrow.
What is Ultraviolet (UV)
Ultraviolet or “UV” is a type of energy found in the electromagnetic spectrum, lying between x-rays and visible light. Although we cannot see UV light or rays, we are
exposed to them every time we step out into the sun. In fact,
UV light is responsible for causing sunburns. Ultraviolet systems
use special lamps or bulbs that emit UV light of a particular wavelength.
The Ultraviolet energy attacks the genetic core of the microorganism and rearranges the DNA /RNA eliminating the microorganism's ability to function and reproduce. If the microorganism can no longer reproduce, it cannot replicate, therefore it cannot infect other organisms with which has contact. The process is simple but effective,
destroying 99.99 percent of harmful microorganisms without adding
chemicals to the water.
The quality or appropriateness of both the UV light and of the 'contact ', are crucial to accomplish disinfection. It is important to properly 'size' the UV based upon the application. It is equally important to use a good pre-filter to remove any dirt or debris that may be present in the raw water supply. This dirt and debris can interfere with the effectiveness of the UV rays – virtually giving the microorganism a shield to protect them when passing the UV rays. The keyword here is quality. System manufacturers strongly recommend that any pre and post filters be replaced at specified periods and that the UV lamp be replaced on an annual basis or after 9,000 hours of use -- whichever comes first.
Advantages of UV
There are some very important reasons why both homeowners
and municipalities are choosing UV technology to treat their water.
What is Ultraviolet (UV)?
Sunlight has long since been known to kill micro-organisms.
The rays from the sun contain the UV Spectrum used in Ultraviolet
Water Treatment Systems – although at much lower intensities.
It is also referred to as either Germicidal Spectrum or Frequency.
The frequency used in killing micro-organisms is 254 nanometers
(nm). The UV lamps that we use are designed specifically to have
the highest amount of UV energy at this frequency.
How is Ultraviolet
The UV light, 254 nm, is measured in water treatment
as Microwatts per Centimeter square. The United
States Department of Health has determined that an effective
UV system should provide a minimum of 16,000 Microwatts per Centimeter
Is the UV light
exposed directly to the water?
Yes and No. Yes, the rays are exposed, no the bulb
is not. The UV light is in the center of the filter, surrounded
by a clear quartz sleeve. The bulb is protected by this sleeve.
The sleeve is exposed directly to the water. The best way to penetrate
water with the UV light is to expose outward radiants into the
water and the UV rays penetrate the water to kill microorganisms.
What is the Quartz
The Quartz Sleeve serves three purposes. 1. To isolate
the lamp from the water so the lectrical contacts are not shorted
out by the water. 2. To create a thermal barrier allowing the
lamp to maintain its ideal operating temperature of 104 Degrees
Fahrenheit and 3. To allow maximum transmission of the UV energy
into the water. The Quartz Sleeve is made of pure-fused Quartz
which has a transmission rate of approximately 98 percent.
How is the
Quartz Sleeve cleaned and how often should it be cleaned?
The Quartz Sleeve should be wiped down with a damp
cloth each time the lamp is changed. On some models the Quartz
Sleeve can be cleaned without being removed from the UV system.
In some cases the sleeve cannot be cleaned but should be discarded
How often should the
UV lamp be changed?
The UV light is designed to operate for (1) year
under continuous operation. The lamp will slowly lose energy during
this period, therefore the lamp should be changed annually to
guarantee the amount of UV energy available is sufficient enough
to kill micro-organisms.
Does UV purification
make the water taste better?
The UV energy entering the water has no effect
on the taste and odor of the water with the exception that certain
chemicals will oxidize under the UV light. The taste may change
due to this oxidation. This oxidation only takes place when the
water is standing for a long period of time in front of the UV
Should UV be used
with other forms of filtration?
Yes, Because UV does not change the quality of
the water other than killing the bacteria and virus, it is always
recommended that Sediment pre-filter and Carbon post-filter are
used with a UV lamp. This configuration makes a complete UV System.
Why is it necessary
to use a 1 micron filter with my UV system?
The outer layer or shell of a cyst is extremely
difficult to penetrate with a UV light. Because of the, UV manufacturers
recommend that a 1 micron (absolute) filter be included in the
When used with other
filters, where should the UV be placed?
The UV lamp should always be preceeded with a prefilter
and followed with a carbon filter. It is always recommended that
the Ultraviolet system itself be the last water treatment device
before the point-of-use. Any filter or other water treatment devices
may cause re-contamination.
What causes black
particles to appear in the water when using a carbon filter with
The black particles that appear in the water are
from the carbon filters used with the UV light. When the carbon
filters are first put into use a small amount of carbon particles
may appear in the water. These particles are harmless and are
flushed out during the initial use of the filter.
Is ultraviolet as harmful
No. The UV light only penetrates the water and
is very much like sunlight. There is no residue or residual of
any kind in water that has been treated with the Ultraviolet light.
It is important to always use caution when servicing a UV system
so you are not exposed directly to the UV light.
How much water pressure
is required to operate most UV systems?
Most UV systems are designed to operate ideally
at approximately 65 psi (pounds of pressure per square inch).
Although many systems may operate with pressures as low as 20
psi, the flow rate will greatly decrease due to the low water
pressure. It is always recommended that if the pressure exceeds
75 psi a pressure reducing valve should be used.
Can I run hot water through
my UV system?
It is not recommended to run hot water or water
greater than 100 Degrees Fahrenheit through the UV system. At
higher temperatures plastics and rubber may soften, distort or
weaken causing the system to fail.
If the UV lamp is darkened,
is it defective or not working properly?
No. Darkening at the end of the UV lamp is normal.
The UV lamps rarely fail, and when they do it is usually caused
by voltage that is to high or to low. It is extremely important
that the UV lamp be replaced on an annual basis.
What is the difference
between hard and soft glass UV lamps?
Hard glass is pure-fused Quartz and maintains its
ability to transmit UV light over a longer period of time than
soft glass. Soft glass lamps use a glass more like normal window
glass. The UV light causes this glass to solarize and inhibits
the transmission of UV light. Normally soft glass has a life span
of 90 days, where hard glass lamps are designed to operate for
at least one (1) year.
If I turn the UV lamp off
while it is not in use, will it last longer?
No, It is not recommended to turn the UV light
on and off unless the system has been specifically designed to
do so. The on and off cycling of a UV lamp that is designed to
be left on at all times can cause premature lamp failure. On average
the lamp can loose as much as six (6) hours of lamp life each
time it is turned on and off.
Can I use filters
other then the ones provided with the system?
It is recommended that you not use filters other
than those whos specifications match the specifications of the
filters that came with the system. Filters that do not meet these
specifications will reduce the effectiveness of the system.
How long should the
Filters should normally last six – twelve (6-12)
months depending on the quality of the water. In areas where the
water has a high amount of sediment, it is recommended that you
use a double or triple system, which has a Sediment (SD) filter
before the carbon filter (s). ESP does offer a larger sized filter
that will last longer under heavy sediment conditions.
Can I use UV for the
whole house at the point of entry?
Yes, A UV system can be used to treat the entire
house. There are several UV systems designed specifically for
this application. It is very important the lines in the house
be cleaned before using the UV system. If the lines are dirty,
the water will re-contaminate after the UV system is installed.
It is easiest to sterilize the lines by introducing a chlorine
solution and letting it stand for a period of time.
Why does the flow rate
reduce with the use of Sediment and Granular Activated Carbon
The Pre & Post Filters will create a resistance
or back-pressure on the incoming water flow reducing the flow
rate of the water.
Do ordinary filters
No. Ordinary filters cannot kill bacteria. The
bacteria will enter the filter and either pass through the filter
or grow within the filter. The UV light should always be the last
pass after the filters to ensure that bacteria does not pass through
to the drinking water.
Do Carbon filters
Bacteria can survive within a Carbon filter, but
this is normally not a problem if the filter is in continuous
use. If the filter stands for a long period of time, bacteria
What does Bacteriostatic
The term Bacteriostatic means the quantity of bacteria
passing through the system will be static – bacteria will not
multiply. For example: if you have a count of 100 colony forming
units going into the filter you will have 100 colony forming units
coming out. Bacteriostatic filters do not kill bacteria, but only
inhibit the growth of bacteria within the filter.
For additional information on Water
Treatment Systems, refer to frequently asked questions.