What pH means in drinking water

pH measures how acidic or alkaline water is on a scale of 0 to 14. 7 is neutral, below 7 is acidic and above 7 is alkaline. The scale is logarithmic, so pH 6 is ten times more acidic than pH 7.

Guideline range

The US EPA's secondary (non-enforceable) guideline for tap water is pH 6.5 to 8.5. It is set for taste, corrosion and staining, not as a health limit.^[5] The FDA bottled water standard of quality does not set a pH limit.^[1]

Why sparkling water has a lower pH

Dissolved carbon dioxide forms carbonic acid, which lowers pH. That is why sparkling waters in our data (for example S.Pellegrino at pH 5.18, measured on the carbonated product) read lower than still waters. Highland Spring, for example, says its still water is about pH 7.8 and its sparkling water pH 4 to 5.

"Alkaline" water

Some brands sell water with a high pH (Essentia reports an average of 9.92). A high pH number on its own says nothing about mineral content: Essentia's TDS (61 mg/L) is lower than most natural mineral waters in our list. We report pH as published and make no health claims about it.