A water impurity is any substance other than water that found in the water sample, whether harmful or beneficial.
For example, Total Petroleum Hydrocarbon (TPH) is a water quality that result mainly from the release of petroleum products into the household well . This parameter is unregulated impurities (Permenkes No 492 Tahun 2010) but this analysis is useful in case of pollution problems
Impurities can be divided into three classes :
1. Regulated impurities (pollutants) considered harmful or aesthetically objectionable
2. Unregulated impurities not considered harmful
3. Unregulated impurities not yet evaluated for their potential health risks
In water quality analysis, unregulated as well as regulated impurities may be measured
A. Natural Sources
Snow and rainwater contain dissolved and particulate minerals collected from atmospheric particulate matter and a small amount gases dissolved from atmospheric gases. Snow and rainwater have virtually no bacterial content until they reach the surface of the earth.
After precipitation reaches the surface of the earth and flows over and through the soil, there are innumerable opportunities for introduction of mineral, organic, and biological substances into water. Water can dissolve at least a little of nearly anything it contacts from the atmosphere and soil. Because of its relatively high density, water can also transport suspended solid. Even under pristine conditions, surface and ground-water will usually contain various dissolved and suspended chemical substances.
B. Human-Caused Sources
Many human activities cause additional possibilities for water contamination. Some important sources are :
– Construction and mining
– Industrial waste
– Petroleum leaks and spill
– Agricultural application
– Urban storm water runoff
– Effluents from industries and waste treatment plant
– Leachate from landfill, septic tanks, treatment lagoons and mine tailing
– Fallout from atmospheric pollution
Eugene R. Weiner. Application of Environmental Aquatic Chemistry. A Practical Guide. Third edition. CRC Press