Better mention a caveat about SODIS, since it's come up as an alternative to chemicals. SODIS is not recommended at latitudes higher than - I believe it was 40-degrees. At higher latitudes the intensity of sunlight may be insufficient to guarantee sterility in any reasonable time span.
Now I gotta say one thing about this method that perhaps some don't care about, but I do. I wouldn't use SODIS unless every other form of water treatment I possess was used up/broken. It takes too long (6 hours at North American latitudes), the water ends up warm or even hot (yech), and water high in organics ends up smelling like a swamp (breakdown of sulphur-bearing compounds). The people that this method is targeted at may be used to this, but my overly-civilized palate prefers water that lacks those qualities. I never liked iodine or chlorine either, so these newer technologies of chlorine dioxide, MIOX, and UV are the greatest thing since sliced bread to me.
FWIW, I see how well UV sterilization works in my fish tank. I have ZERO bacterial/algal activity in the water. My fish have been disease free for over two years. I'd trust it implicitly as long as the water is clear. For cloudy or brown (tannin bearing) water I'd fall back on chlorine dioxide or MIOX.