Total Hardness Test Kit (LR) – LH-2012




  • Fill the pipette to the 10 ml mark with sample.
  • Add the water to the clean flask.
  • Add contents of one Total Hardness (I) (LR) reagent to the flask and swirl to dissolve. A blue color indicates the hardness is 0 mg/L. If a red color develops, proceed to step 4.
  • With swirling add the Total Hardness (II) (LR) reagent drop by drop untill the color changes from red to blue, Count the number of drops (N).
  • Calculate the results. Total Hardness = N x 10 (mg/L, as CaCO3).


  • Rinse flask with deionized water before the test.
  • The pH must be within the range 6-9. Adjust if necessary, with NaOH or HCl.
  • When pipetting, if there are air bubles in the pipette, pull and push the piston repeatedly with the suction port immersion in the liquid.