I don't want to sound all preachy about it, but after I had a closer examination of the TSD (total dissolved solids or somthing like that) in my home water supply, I stopped drinking out of the tap quickly! I am in a newer building, very close to the top floor, and the water tank, being on the roof, passes through fewer pipes to reach me, and yet my filters still catch quite alot after 6-8 months. When I was living on the bottom floor of an older bldg, my w/r faucet actually stopped working once (no water coming out at all) there was so much crud caught in the tap.
So considering jr would be drinking alot of liquids, it was a no brainer to filter out the nasties if we could do so relatively easily.
BTW, to the original poster: I found the prices on Diamond ads to be quite high - probably to pay for the marketing budget in all the glossy home deco mags.