2)organoleptic (aesthetic) analysis and physical analysis of drinking water
-drinking water should not only be safe and free from dangers, also aesthetically attractive (absence of turbidity, color, disagreeable or detectable taste and odor,)
-> changes in color, tastes or normal appearance may be a signal to lowered water quality
COLOR DETERMINATION
-drinking water should be free from color (colored organic matter, metals or industrial waste)
-measured by spectrophotometer, simple colorimeter or using visual comparison with known standards
-principle of determination: color of tested water is compared with colored standard scale
- Results are expressed in true color units
- According to BGN instruction No# 9 -> acceptable to consumer and no abnormal changes OR no more than 15 true color units
ODOR DETERMINATION
-difficult to measure, several causes (organic matter, dissolved gases, industrial waste…), most frequently caused by algae or organic matter, abnormal odor could indicate presence of harmful substances
-2 groups of odor in water: unnatural odor and odors of natural origin
-principle of determination: odor testing device -> human nose (provide qualitative description and approximate quantitative measurements of intensity), determination on cold (18-20°C) or on heating (60°C), 100ml of water placed into Erlenmeyer flask of 300ml capacity and closed with glass stopper, water is agitated by circular movements, stopper is opened -> water is smelled
-qualitative descriptions: aromatic, fishy, grassy, musty, septic, medicinal
-quantitative intensity: water odor scale (0=any; 1=very weak; 2=weak; 3=appreciable; 4=strong; 5=very strong)
- According BGN instruction No# 9 water should be acceptable for consumer and no abnormal change in odor OR no more than 2 bales at temp. 20°C
WATER TASTE DETERMINATION
-is determined by the presence of substances depending on their origin or substances utilized in the treatment process
-groundwater contains salts as taste forming substance (potassium, sodium, magnesium, chlorides, carbonates…)
-principle of determination: determined by the organoleptic method (human receptor, people without any defects in taste perception)
-taste is describes as salt, sweet, sour, bitter (different variation of possible aftertastes -> metal, alkaline, mint…)
-temperature is important -> teste at temperature at the moment of sampling, at room temperature and at ca. 40°C
- according to BGN instruction No#9 the taste of drinking water should be acceptable to the consumer and no abnormal changes at temperature 20°C
WATER TURBIDITY DETERMINATION
-is the measure of suspended solids -> affects treatment processes and especially disinfection with chlorine based chemicals (turbidity can protect microorganisms in water)
-it’s the measure of water purity