The installation of a UV water purifier requires precision and attention to detail. Improper installation can lead to the system not working as intended, or even damaging pipes or purification equipment. Before water enters the UV light chamber, it is recommended that it first pass through a sediment prefilter. This ensures that the water is clear enough for effective UV disinfection.
If the water is cloudy, UV light may not be able to contact or destroy dangerous microbes in the water. Used alone, UV radiation does not improve the taste, smell, or clarity of water. UV light is a very effective disinfectant, although disinfection can only occur inside the unit. Unlike chlorination, there is no residual disinfection in the water to inactivate bacteria that may survive or enter after the water passes through the UV source.
The percentage of microorganisms destroyed depends on the intensity of the UV rays, the contact time, the quality of the raw water and the proper maintenance of the equipment. If material accumulates in the quartz cover or the particle load is high, the intensity of the UV rays and the effectiveness of the treatment are reduced. At sufficiently high doses, all waterborne enteric pathogens are inactivated by UV radiation. However, installing and using UV lights is not as simple as changing old bulbs and putting in new ones.
There are specific safety measures, requirements, and guidelines that must always be followed. In recent years, medium-pressure UV lamps have been commercialized that operate at much higher pressures, temperatures and power levels and emit a broad spectrum of higher UV energy between 200 and 320 nm. UV-C products that make a medical statement and require FDA approval include medical UV air purifiers and UV camera disinfection devices. Hard water can cause lime to accumulate in the UV lamp, reducing its effectiveness.
Some are equipped with UV emission detectors that alert users when the unit needs cleaning or when the light source is failing. The typical UV treatment device consists of a cylindrical chamber that houses the UV bulb along its central axis. These lamps emit almost monochromatic UV radiation at a wavelength of 254 nm, which is in the optimal range for absorption of UV energy by nucleic acids (around 240-280 nm). UV radiation breaks bonds in nucleic acids and kills microorganisms. However, dissolved organic matter such as natural organic matter, certain inorganic contaminants such as iron, sulfites and nitrites, and suspended matter (particles or turbidity) will absorb UV radiation or protect microbes from it, reducing doses administered and microbial disinfection. The Occupational Health and Safety Administration (OSHA) has regulations to protect workers from radiation in the workplace; however, there are currently no limits on exposure to ultraviolet light.
Because these devices don't actually contain any pesticides, they don't require EPA registration. The UV water purifier must be installed before the water heater but after all other water treatment systems in your home such as water softeners, reverse osmosis systems, well pumps and pressure tanks, water filters and deionizers. In most cases, these systems are not necessary but people install them for peace of mind that they will be protected against contamination of their water supply. If you have “hard” water (water high in magnesium and calcium), you'll most likely want to install a water softener in front of your UV water treatment system. Similar results have been obtained with pulsed low-pressure and medium-pressure UV irradiation. Look for a Class A UV disinfection system.
Both the Society for Lighting Engineering and International Ultraviolet Association have published frequently asked questions about UV-C products and how germicidal UV light disinfects air and surfaces. If you are installing a UV drinking water system under your kitchen sink, typical flow rates for this type of system are 1 to 9 gallons per minute (such as Viqua VH200). It is important to remember that proper installation is key to ensuring your system works effectively.
