Standard plate test results levels are meaningless re safety for bottled water:
http://www.who.int/water_sanitation_health/dwq/HPCFull.pdf
1.3.1 Bottled water
Bottled (“packaged”) water is considered drinking-water under some regulatory
schemes and as a food in others. Some authorities distinguish between natural
mineral water and other bottled waters. The WHO Guidelines for Drinkingwater
Quality are referred to directly in international norms (Codex
Alimentarius Commission) and are considered applicable to bottled waters.
Bottled waters represent a specific growth situation for microbial flora.
Bottled waters may derive from “pristine” sources (“natural mineral water”) or
from processed waters. They may contain or have added carbon dioxide that
will restrict growth potential, but typically no long-lasting disinfectant residual
is present. The finished product will often be exposed to elevated (ambient)
temperatures over a period of days to weeks before consumption.
Microorganisms naturally occurring in water are a normal part of the
microbiota of bottled waters that meet appropriate safety norms. Levels of HPC
recovered from bottled water post-distribution may therefore sometimes be
significantly higher than those found in municipal water supplies in distribution.
Microbial safety for bottled waters is best pursued by a WSP approach (as
summarized in section 1.2.1). Pseudomonas aeruginosa and HPC values are
used by some as process management indicators in bottled water production and
not as health risk indicators.
