What is a test for water purity?Question from my Year 11 chemistry textbook: 8b) Describe a test to show that a sample of water is pure.

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ncchemist eNotes educator| Certified Educator

There are numerous tests for water purity.  One is a pH test.  This measures the acidity level of the water.  Simply dip a pH test strip into the water and check the colors seen against the color scale on the pH paper packaging.  It should read between 5.5 and 8.5.  You can do a TDS test to measure the total dissolved solids.  Simply dip a TDS meter into the water to get a reading.  Readings should be below 500 mg/liter.  One final test is for total coliform bacteria, or harmful bacteria that can cause illness.  This should be performed by a professional tester.  Any local health department can test a sample of water for dangerous coliform bacteria.