If you're considering installing a domestic water purifier, then UV water purification certainly is a type of system you might want to consider.
Ultra-violet light purification offers some advantages over chemical systems, but it also have some disadvantages.
We'll discuss this in some detail in this article.
What is UV Water Purification? Ultra-violet water purification systems basically disrupt the genetic material of an organism through the transference of electromagnetic energy to the organism through the use of a mercury arc lamp.
The ultra-violet radiation penetrates the DNA and RNA of the microorganisms you want to kill and essentially negatively affects their ability to reproduce.
This method of water purification works to kill bacteria such as e-coli, salmonella, and others.
It also kills microorganisms such as Giardia and Cryptosporidium.
Advantages UV water treatment offers some advantages over other means.
Some of these advantages are:

• It kills most viruses, spores, and cysts
• It uses a physical process rather than a chemical process
• There is no residual, harmful effect on humans
• It's relatively easy to use
• UV equipment requires less space than other methods

Disadvantages There are some disadvantages, however.
Some of which are:

• Low dosages may not be enough to kill some spores and cysts, and other organisms
• Sometimes organisms can repair themselves
• You have to maintain the system
• Turbidity can make the UV system ineffective (because the light can't get to the organisms you want to kill)
• It's not as cost effective as chlorination

Alternatives If you're thinking of using UV treatment for domestic use, there might be some other alternatives you want to consider.
One of the things you need to consider is whether or not you're purifying water that's "already purified" such as tap water, or if you're purifying the water for the first time--say water that comes out of a well.
Another issue is the amount of non-organic contaminants that are present in your water.
UV can kill Giardia, but it's not going to help get rid of trace amount of pesticides, for instance.
There are certainly other water purification technologies available--reverse osmosis, and filtration through activated carbon being two possibilities.
Each has its pros and cons.
Reverse osmosis works well, but it wastes water and it also filters out trace minerals that we actually need in our water.
You need those trace minerals for taste, and also for health.
Activated carbon needs to be replaced frequently.
If you're looking for a home water purifier, there are some on the market that use several cutting edge technologies together to produce pure water that also contains the trace minerals you need for optimum health.