I installed the tablets at least 4 weeks ago (might have been 5). I noticed a lot of reviewers complained about pink water, but that hasn't happened. My water is actually still blue! Light blue, but still blue. The tablets do keep the lower part of the bowl clean (where the water touches). The upper part of the bowl still needs to be cleaned regularly of course, because water (and the 2000 flushes) only touches the upper part of the bowl when the toilet's flushed.