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Other Aesthetic Contaminants
About the Project
Home > Education > Contaminants & Risks > Drinking Water Contaminants > Other Aesthetic Contaminants​​
About Other Aesthetic Contaminants - Secondary Standards
Since the passage of the Safe Drinking Water Act (SDWA) in 1974, the United States Environmental Protection Agency (USEPA) has been responsible for developing standards limiting exposure to contaminated drinking water. Under the SDWA, a list of standards sets monitoring requirements and limits on the maximum acceptable levels of specific contaminants allowed in drinking water supplied by public systems (i.e., not including private wells serving fewer than 25 persons). 

There are two types of standards that regulate contaminants in drinking water:
  1. The National Primary Drinking Water Regulations (NPDWR)​ regulates substances harmful to human health, including:  Arsenic, Cryptosporidium, Lead & Legionella​
  2. Secondary standards addresses substances that may cause foul tastes and odors in the public water supply. Acceptable secondary maximum contaminant levels (MCLs) are recommended, but not enforced.  

Continue reading for the full list of secondary standards from the USEPA and resources for each contaminant.  
​WQRF Contaminant Occurrence Map
Check out the Contaminant Occurrence Map for visual representations of drinking water quality data for public water systems across the US. Map data is available for several secondary contaminants, including: iron, manganese, and pH.

To View the Data:
  • Review "About the data" and click to acknowledge
  • On the left side, click the first dropdown option and scroll down to Aesthetics > [contaminant name]
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Contaminant​
Secondary MCL*
Noticeable Effects 
Resources
Aluminum​
0.05 to 0.2 mg/L​
colored water​
WQA: Aluminum [Link]
WQA Technical Factsheet: Aluminum [Link]
Chloride​
250 mg/L
salty taste
USGS: Chloride, Salinity, & Dissolved Solids [Link]
Color
15 color units
visible tint
USGS: Water Color [Link] 
Copper**
1.0 mg/L
metallic taste; blue-green staining
WQA: Copper [Link]
WQA Technical Factsheet: Copper [Link]
Corrosivity
Non-corrosive
metallic taste; corroded pipes/ fixtures staining
USGS: Corrosivity [Link] 
Fluoride**
2.0 mg/L
tooth discoloration
WQA: Fluoride [Link]
WQA Technical Factsheet: Fluoride [Link]
Foaming Agents
0.5 mg/L
frothy, cloudy; bitter taste; odor
 
Iron
0.3 mg/L
rusty color; sediment; metallic taste; reddish or orange staining
USGS: What can be causing our drinking water to have a reddish color? [Link]
Contaminant Map Aesthetics > Iron
Manganese
0.5 mg/L
black to brown color; black staining; bitter metallic taste
WQA: Manganese [Link]
11/2010 On Tap Article [Link]
​Contaminant Map Aesthetics > Manganese
Odor
3 TON (threshold odor number)
"rotten-egg", musty or chemical smell
WQA Technical Factsheet: Taste & Odor [Link]
pH
6.5 - 8.5 ​
low pH: bitter metallic taste, corrosion; high pH: slippery feel, soda taste, deposits
USEPA: pH [Link]
USGS: pH and Water [Link]
​​Contaminant Map Aesthetics > pH
Silver
0.1 mg/L​
skin discoloration; graying of the white part of the eye
WQA: Silver [Link] 
WQA Technical Factsheet: Silver [Link]
Sulfate
250 mg/L
salty taste
USEPA: Sulfate in Drinking Water [Link]
Total Dissolved Solids (TDS)
500 mg/L
hardness; deposits; colored water; staining; salty taste
USEPA: Total Solids [Link]
Zinc
5 mg/L
metallic taste
CDC: Zinc [Link]
*MCL = Maximum Contaminant Level - The highest level of a contaminant that is allowed in drinking water
**Higher levels of these contaminants are enforced and require notification under the NPDWR
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  • Home
  • About
    • About WQRF
    • WQRF Board
    • Annual Reports
  • RESEARCH
    • Ongoing Studies
    • Completed Studies >
      • 1-Minute for Water Research
    • Softening Benefits Calculator
    • Open RFPs
    • Newsletter
  • Map
  • EDUCATION
  • Next Wave Campaign
    • Campaign Leadership
    • Campaign Supporters
    • Donate
  • MEDIA
    • Webinars
    • News Releases
    • Podcasts
  • Events
    • PFAS Symposium
    • Walk for Water