What Quality is Your Drinking Water?
Water quality must meet microbial standards to prevent diseases. It must also meet chemical standards to prevent health risks associated with toxic chemicals.
In addition, its criteria are numeric or narrative guidelines that protect or support a designated use.
So, you can express these criteria as either concentrations (milligrams per litre, parts per million) or as narrative statements.
Therefore, if you meet the water quality criteria, your level of water quality will generally protect your designated use.
Criteria for Water Quality Analysis
- Physical and
Chemical: Dissolved elements, toxic substances, pH and corrosiveness, salts.
Physical: Temperature, suspended solids, odor.
Biological: Microbes; pathogens (coli form bacteria)
Water Quality Indicators
Microbial: Bacteria, Algae, Viruses, Protozoa and Helminths
Turbidity: The measure of suspended and colloidal particles. Particles like soil, algae or other materials may be small or big that you can barely see with your naked eye.
Corrosiveness (pH and alkalinity): Here, you measure how acidic or basic the water is. The measure of the balance between the positive hydrogen ions (H+) and the negative hydroxide ions (OH-).
Corrosiveness occurs due to these ions either missing of an electron on the hydrogen ion or existence of an extra electron as in the case of the hydroxide ion.
Water has a pH of 7 which means it has an equilibrium of electrons from both ions.
- Disinfectant by-products: Total trihalomethanes (TTHMs) and Haloaetic Acids (HAAs) are by-products of disinfection treatment with chlorine.
Chemical (inorganic and organic)
- Mineral analysis
Standards for Drinking Water
Microbial Quality: Pathogens- Coliforms typically survive treatment and readily detected. E. coli has been sufficient to cause public concern.
In today’s media, you may find announcements/warnings on water contamination. You may be urged to boil your water before drinking due to poor standard of the water. In short, it is not safe for your health!
So, what are these standards?
MCL- (maximum contaminant level) enforceable standard. This is the highest level of contaminant allowed in drinking water.
MCLG- (maximum contaminant level goal) non-enforceable goal. This means there is no known or expected risk to our health.
MCLs set as close as possible to MCLGs
MCLs have been developed for:
- Inorganic chemicals: Lead, Fluoride and Nitrate.
- Volatile organic chemicals (VOCs): carbon tetrachloride, vinyl chloride. Adverse effects include cancer, effects on liver, kidneys, nervous system. Synthetic organic chemicals
- Disinfection by-products and disinfectants: Trihalomethanes (THMs) & Haloacetic acids (HAAs)
- Not related to health hazards
- Chloride, sulphates (taste, laxative effects)
- Iron and manganese (staining of laundry and porcelain fixtures)
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