Butterfield's Phosphate Buffered Dilution Water ,pH 7.2 is used for preparation of microbiological dilution blanks. This buffer is used rather than unbuffered water in order to standardized this potential variable due to the wide variation in the pH of distilled water from multiple sources. Butterfield’s Phosphate Buffered Dilution Water is specified by the American Public Health association (APHA) for use in diluting test samples. Butterfield’s Phosphate Buffered Dilution Water is specified for use in diluting water, dairy products and food for microbiological methods.