http://green.yahoo.com/blog/the_cons..._kWXp_qIbJV8cX

Just came across this on yahoo, maybe this will help to see if your TDS ratings are acurate, i.e, if you get 20ppm and your in Walnut (Or chino hills), theres something wrong with your TDS meter. Just thought this was nifty (NO,people didn't start saying that word).