# Using non-food grade NaOH for pH control

I would like to use non-food grade $\ce{NaOH}$ for $\ce{pH}$ water treatment. Any problem with this mixing with water that contains iron?

The $\ce{NaOH}$ will be pumped into a well. As a $25\%$ solution. Then sent through an ozone filter and a water softener. Eventually, it will be used for pet and human consumption.

• In addition to what thomij has already pointed out, note that $\ce{NaOH}$ etches glass and will degrade various polymers (PET and polycarbonate, among others). – Greg E. Aug 20 '14 at 0:33
• What about passing the water through calcium carbonate or magnesium hydroxide to raise pH? – Brinn Belyea Aug 20 '14 at 1:10
• Non-food grade sodium-hydroxide can (and most often do) contains heavy metals. Also, it is pretty corrosive, so you may yourself generate different carcinogens or poisonous side-products inside the well during this process. If you want to use this for human / pet consumption, you may want to consider other solutions, e.g. @brinnb's suggestion. – Greg Aug 20 '14 at 3:19

Iron hydroxide is insoluble, so it will precipitate out. If there are other metals that aren't alkali metals or alkaline earth metals heavier than calcium, they will also precipitate out. Most of these reactions will release some heat, but if the concentration of the metal ions is low, that shouldn't matter too much.

If you plan to drink the water, using non-food grade $\ce{NaOH}$ might cause a problem, because you won't know what else is in there.

If you add more details, we can probably tell if there are any other things to be concerned about.