Our property is rich in water, but none of it is safe to drink.  We have two creeks which work great for irrigating the garden and a hand-dug well which people presumably drank from decades ago.  Unfortunately, the well tested positive for coliform bacteria.

Coliform bacteria, while not necessarily dangerous by themselves, are a sign that the water has come in contact with the fecal matter of a mammal at some point, and thus mean the water isn't safe to drink.  Many people who drink from shallow wells or springs build up an immunity to the problematic bacteria, but we didn't want to risk it, especially since it would mean that guests might get sick drinking our water.  So, for the first year and a half, we carried our drinking water into the property a gallon at a time from a friend's house a mile down the road.

Then came the economic stimilus checks this spring.  We decided to see if we could get our drinking water system up and running for a couple of hundred bucks, and sure enough we did! 

After researching all of the options, I quickly decided that a UV light is the best treatment system for home drinking water --- actually, a lot of municipal water treatment plants are moving toward UV treatment and away from chlorine since UV is completely safe and leaves no nasty aftertaste.  The cheapest UV system I came across was the Omnipure Pacific from FreshWaterSystems.com.  We opted for the 1 gpm 6 watts sytem with ballast, and bought an extra light since the light has to be changed about once a year.

The one thing you have to be aware of when installing a UV treatment system is that the water needs to be very clear for the system to be effective.  Any tiny grains of dirt suspended in the water will act as a shield, protecting bacteria from the light and making the "treated" water unsafe.  The bare minimum is to install a 5 micron sediment filter upstream of the UV light system so that the water runs through the sediment filter and is cleaned before running through the UV system.  You can get sediment filters just about anywhere, but we got ours from the same place to save on shipping.  In the end, our treatment system cost under $200.

Another thing you should consider when installing a water treatment system is your water source.  The system I've outlined here (and also the systems used to treat most municipal drinking water) are designed to remove only sediment and microorganisms.  If you pump water from a creek which gets pesticide runoff, the pesticides will still be in the water after you treat it!  So you're far better off starting off with groundwater (from a well or spring) and preferably also using water from a watershed which is completely forested.

We made one change from the normal installation procedure.  While most people would install a pressure tank which automatically kicks on the well pump whenever it gets low and leave the UV light plugged in at all times, we opted for a cheaper and lower power system.  Mark rigged up a reservoir above the kitchen sink to hold our drinking water.  Once a day or so, we flip the switch on the power strip which turns on the UV light and well pump and lets the water rush through the sediment filter and UV system to fill up the reservoir.  Then we turn off the power strip until the next day.  Used this way, we suspect our UV light will last for several years instead of just the one promised by the manufacturer.  And now we have clean, running, drinking water piped to our kitchen sink!  No more carrying frozen jugs of water for half a mile to the house in the winter.