Monitoring Contaminants

Results of Monitoring for Regulated Contaminants
To ensure the safety of your drinking water, the Maui Department of Water Supply routinely monitors for contaminants in your drinking water according to Federal and State Laws, rules, and regulations. The following is a list of contaminants that were tested.

Inorganic Contaminants
  • Asbestos - MCL = 7 MFL
    • Major sources: decay of asbestos cement water mains, erosion of natural deposits
  • Chromium - MCL = 100 ppb
    • Major sources: discharge from steel and pulp mills, erosion of natural deposits
  • Nitrate - MCL = 10 ppm
    • Major sources: runoff from fertilizer use, leaching from septic tanks, erosion of natural deposits
  • Turbidity - TT = 5 NTU; TT = percentage of samples less than 0.5 NTU
    • Major sources: soil runoff
Microbiological Contaminants
Coliforms are bacteria that are naturally present in the environment and are used as an indicator that other, potentially harmful bacteria may be present. If coliforms are found in samples, this could signal a warning of potential problems. Chlorine levels would be raised and extensive bacteriological testing conducted to monitor the systems.

Radiological Contaminants
  • Gross beta emitters - EPA considers 50 pCi/L to be the level of concern for beta particles
    • Major source: decay of natural and man-made deposits
Synthetic Organic Contaminants
  • Hexachlorocyclopentadiene
    • Major source: possible by-product of water chlorination
Volatile Organic Contaminants
  • TTHM (Total trihalomethanes)
    • Major source: by-product of drinking water chlorination