Re: How is the concentration of ozone in fresh water determined? I'm looking fo

There aren’t any really precise methods for measuring ozone in water at home. That is, the easiest tests to use at home are interfered with very easily. If you know that ozone is the only oxidant, you can measure with colorimetric tests such as N,N-Diethyl-p-Phenylenediamine (DPD) test strips or solutions added from a dropper bottle or tablets into a small sample of water. The test strip or water sample is then compared to color samples to determine the concentration. For about $75, you can acquire a color comparator and enough testing chemicals for 50 tests. If you don’t need to have quantitative results (testing for presence/absence), you can use test strips prepared with starch iodine solution. They darken in the presence of oxidizers.

If chlorine alone is interfering with the test, an alternative test using indigo trisulfonate has a step that eliminates free chlorine, but other free oxidants such as bromine or peroxides would still interfere, and you have to use a colorimeter to read the results. I assume that you are trying to avoid any large capital purchases of electronic equipment.

As far as other tests, simple (strip, tablet or dropper) methods are available for acidity, algae, alkalinity, aluminum, ammonia nitrogen, bacteria, biochemical oxygen demand (BOD), bleach, bromine, cadmium, calcium, carbon dioxide, caustic, chelant, chloride, chlorine, chlorine dioxide, chromate, chromium, coliform, color, copper, cyanide, DEHA, detergents, filming amine, fluoride, formaldehyde, gluteraldehyde, hardness, hydrazine, hydrogen peroxide, iodine, iron, lead, manganese, molybdate/molybdenum, morpholine, nickel, nitrate nitrogen, nitrite nitrogen, sodium nitrite, dissolved oxygen, ozone, peracetic acid/hydrogen peroxide, pH, phenols, phosphate, phosphate (total), phosphonate, polyphosphates, polyquat, potassium, QAC, salinity, SDMBT, silica, sodium, sodium nitrite, sulfate, sulfide, sulfite, tannin/lignin, total dissolved solids (TDS), turbidity, and zinc, just to name a few.