Topic 2. Interior Plasters

Practical exercise No. 5 Informative tests on water

1. Visual examination

Equipment: clean transparent container (cup) or test tube

Procedure: Put the water sample in a container and observe against the light. We evaluate the appearance and occurrence of impurities.


  • clear, transparent, translucent – suitable
  • slightly cloudy, strongly cloudy – unsuitable
  • without impurities, with impurities


2. Smell test

Equipment: container or tube with cap

Procedure: Seal the water sample in a container, leave closed for 5 minutes (smell intensifies). Then open and smell.


  • odorless
  • faint odour
  • strong odour (+ description of the type of odour)


3. pH test

Equipment: litmus paper (pH indicator)

Procedure: Soak the paper in a water sample for 30 seconds.

Evaluation: We compare the paper color to the scale and determine the pH of the sample. Water having a pH = 6-9 is suitable.


4. Test for organic matter

Equipment: container with lid

Procedure: Shake the water sample in the container for 30 seconds.

Evaluation: If the foam disappears within 5 seconds, the water is free of organic substances.


5. Presence of sulphates

Equipment: barium chloride BaCl

Procedure: Add barium chloride solution to water and observe for discoloration.

Evaluation: If the solution turns white or even forms a white precipitate, the water contains a sulfur compound (sulphates) and is not suitable for construction purposes.