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Details:
Because aquifers are being depleted at unsustainable rates and subsidence has become a major and ever increasing problem, Houston is switching more and more away from ground water and toward surface water.
This switch brings with it its own set of problems. One of the biggest is the formation of “trihalomethanes”, a group of hazardous chemicals with a legal limit (MCL, or Maximum Contaminant Level) of 100 ppb (parts per billion). This is an extremely small concentration (corresponding to 1¢ in $100,000) and the only way the city can comply with this “MCL”, within its current budget, is to add ammonia together with the chlorine. The chlorine now combines with the ammonia – to form “chloramines” – before it has a chance to form “trihalomethanes” with the organic matter (decaying leaves animal wastes, soil run-off, etc.) in the surface water.
At least part of the reason for this is that chloramines are much more stable (less reactive) than chlorine. Unfortunately, this also makes chloramines much harder to remove from the water than chlorine. Specifically, the “KDF” (a catalytic zinc / copper mixture) shower filters which are so popular these days and work almost magically with chlorine – requiring only a small amount of media, working nearly instantaneous, and lasting for a long, long time –are utterly useless with chloramines. In fact, there had been no practical way to remove chloramines at the shower until Calgon Corp. developed their “catalytic carbon”. This is the media employed in our “SH-CC” shower filter (the “CC” stands for catalytic carbon).
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