Taste and odor

  • The taste and odor of treated water is acceptable to a majority of target consumers.

Key indicators

  • Taste threshold concentrations (TTC) or values:
    • pH 6.5–8.5
    • Total dissolved solids (TDS) <600 mg/L (WHO) (80–450 mg/l considered “excellent” or “good” in the United States)
    • Hardness 100mg/L–300 mg/L Ca2+
    • Cl2 (free chlorine) <0.6 mg/L (may be detected to 0.3 mg/L)
    • Ca TTC = 100–300 mg/L
    • Na TTC = 200 mg/L
    • Fe <0.3 mg/L (typical standard)
    • Cu TTC = <1 mg/L
    • ZnSO4 TTC = 4 mg/L
    • Mn <0.1 mg/L
    • NaCl <200 mg/L (preferred)
    • CaCl2 <120 mg/L (preferred)
    • Bromine 0.6–1.2 ppm
  • Threshold odor concentrations (TOC):
    • NH3 = 1.5 mg/L
    • Cl = 0.3 mg/L
    • Chlorophenols = above taste thresholds (0.1 µg/L)
    • Dichlorobenzenes = 0.3 µg/L (1,4-Dichlorobenzene)
    • Ethylbenzene = 2–130 µg/L
    • H2S = 0.5 mg/L

Notes and exceptions

  • Basic taste attributes are sweet, sour, bitter, salty, and umami (savoriness). Other descriptors include metallic, musty, stale, chlorines, etc.
  • TTCs are often below levels that affect health. TTCs are highly dependent on ions, associated ions, pH, and water temperature.
  • Consumers are very sensitive to inconsistencies in water taste. People accustomed to the taste of local water may not accept changes to that taste, even if the change is subjectively better. Water taste acceptance may need to be tested at the community level.
  • Unpleasant odors in drinking water can have multiple causes, including natural inorganic and organic chemicals, biological sources, and microbial activity.
  • Odors that consumers perceive in drinking water, regardless of source, may create water quality concerns and affect demand.

Supporting evidence

Group of women sitting on the ground around a water treatment device. One drinks water from a cup.

Improved water aesthetics are a critical indicator for the end user. Often, this sustains interest in the device more than what is often a poorly understood health benefit. Photo: PATH.