If you don't already have them, consider using copper piping for transporting drinking water from the tank to the tap. They inhibit bacterial growth.

Have you considered Berkey water filters?

Roland-I like that idea. A small section might not be too hard. It makes me wonder how long the effect lasts once the copper gets corroded? Maybe a short section that can be removed easily and cleaned with a wire brush would maiximize the effect.

Gerry-I considered the Berkey filter, but was weary of buying filters so often, and we know our current system works and is safe.

Like most lamps(light bulbs)have a limited life expectancy, you will eventually have to replace the lamp. Ozone can also be used to disinfect water and making a ozone generator with a small high voltage transformer would be easy just time consuming experimenting with different parts.

@Mark: I don't think the copper would corrode that fast as long as it is submerged in water. And as opposed to PEX, copper water pipes are known for not growing a biofilm, so I suspect that even when tarnished it retains its germicidal properties. Studies have shown that at least tarnished brass retains them.