This elevated temperature heat shocks non-fecal bacteria and suppresses their growth. The red colonies you were looking at on this plate were enterococcus bacteria. 35 o C. Enterococcus bacteria are a valuable indicator for determining the extent of fecal contamination of recreational surface waters. Studies have shown that swimming associated gastroenteritis is related directly to the quality of the bathing water and that enterococci are the most efficient bacterial indicator of water quality. Water quality guidelines have been proposed based on enterococcal density.
Most waters contain some chloride in solution.
The amount present can be caused by leaching of marine sedimentary deposits, pollution from sea water, brine or industrial and domestic waste. Chloride concentrations in excess of 250 PPM usually produce a noticeable taste in drinking water. Chlorides can be removed by distillation, demineralization or reverse osmosis. Iron is an aesthetic problem only. Iron may impart reddish-brown staining to laundry and plumbing fixtures.