. 2011 Jan 5;84(1):20–29. doi: 10.4269/ajtmh.2011.10-0389

Table 2.

Water parameter MCLs and guidelines as set by the US EPA and WHO⁴,³⁵

Water parameter	US EPA (MCL)	WHO guideline	Health-based standard
Water parameter	US EPA (MCL)	WHO guideline	US EPA	WHO
Turbidity (NTU)	≤ 0.3^*	< 0.1^†	Yes	No
Nitrate (mg/L)	10	50^‡	Yes	Yes
pH	6.5–8.5	6.5–8.0	No	No
TDS (mg/L)	500	600–1,000^§	No	No
DO (mg/L)	–	–	–	–
Ammonium (mg/L)	–	1.5^¶	No	No
Chloride (mg/L)	250	250	No	No

US EPA = US Environmental Protection Agency; WHO = World Health Organization; MCL = maximum contaminant level; TDS = total dissolved solids; DO = dissolved oxygen.

Ninety-five percent of samples in a 1-month period with no one sample exceeding 1 NTU (Nephelometric Turbidity Unit).

^†

Median recommended value; however, 5 NTU is acceptable appearance.

^‡

Set as 50 mg/L as nitrate, which is equivalent to 10 mg/L nitrate as nitrogen.

^§

Less than 600 mg/L is best, and above 1,000 mg/L has objectionable taste.

^¶

Based on taste threshold.