Water filtration;
open systems vs closed systems

In one study from March of 1996 published on the US National Library of Medicine website, the quality of filtered water through a Brita was measured in an experimental study in both households and two laboratory settings. 34 filters were tested in households, in which 24 filters increased the bacteria counts in water by as much as 6,000 cfu/ml. Out of 6 filters tested in the labs, 4 of them also increased the bacteria counts. The amount of bacteria was less in the tap water than the filtrated water after one week of use at two different temperatures, one room temperature and another 4 degrees celsius. Therefore, it was concluded that the filter in the Brita had bacteria growing on it during the week it was in use by as much as 10,000 more counts of bacterial colonies than the tap water, not filtered.

Another report from the University of Berkeley on December 6, 2000 concerning filtered water versus tap water found that using a Brita filter is okay if used simply for extra precaution and personal preference of the taste of the water, but the filter does not kill bacteria. The filter traps the bacteria which becomes a breeding ground for other bacteria. Tap water is sanitized by Chlorine, yet if the filter is not changed and contains built up bacteria, it puts extra bacteria back into the chemically filtered water from tap. The problem that arises, and why people partially use filters, is because the tap water can be contaminated from the industrial pipes and drains that it goes through from plants to faucets. Some people prefer to get water through a purified bottle or use a filter because of the smell that the chlorine can cause. Brita filters, though they claim to remove bacteria, heavy leads, and chlorine, do not remove organic chemicals, known as THMs (tribalomethanes), that are naturally evaporated out of tap water but trapped in the filtered Brita. Brita can however be helpful in filtering out chemicals and germs from plumbing issues or other industrial metals and lead but ultimately, this resource concluded that unless there is a serious issue, Brita filters added bacteria and do not filter out microorganisms.

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