EPA

Code of Federal Regulations: Title 40 – Protection of Environment
EPA Source: Click Here
Regulation Summary: Click Here
Hypochlorous Acid: Click Here

Food Contact Surfaces
Hypochlorous Acid may be applied to food-contact surfaces in public eating places, dairy-processing equipment, and food-processing equipment and utensils. When ready for use, the end-use concentration of all hypochlorous acid chemicals in the solution is not to exceed 200 ppm determined as total available chlorine.

Drinking Water
In drinking water, hypochlorous acid should not exceed 4 mg/L (4 ppm). See the EPA National Primary Drinking Water Regulations: Click Here