Testing for Total Alkalinity in Water

The GLOBE hydrology protocol for alkalinity is a tablet-liquid test kit (LaMotte model WAT-MP-DR). Since elementary students are doing the testing under the supervision of a trained adult, the chemical names are left out and colors are substituted. Furthermore, preliminary samples from local surface water show little or no P Alkalinity; thus, use of the white tablets is ignored and total alkalinity is found as parts per million (ppm) as CaCO3.

The resulting simplified procedure is as follows:

Clean, rinse, and fill sample tube to 5 ml line with water to be tested.

Add one black tablet from the dark colored bottle with the black cap. Shake or swirl until tablet dissolves. Solution will turn green-blue.

Fill the syringe to the '0' line with the solution from the black capped plastic bottle.

Cap the test sample tube with the plastic cap and insert the syringe without pushing the plunger.

Add one drop at a time and swirl the test sample tube. Watch for a color change to pink. Stop. Read the scale at the plunger tip being careful to calculate the division scale marks.

If more than one syringe full is used , add the total solution used in both syringes (i.e. 200+......). Total Alkalinity is the direct result of that reading in ppm.