Compare it to the color key. Add a little vinegar to the water and stir. Dip a clean pH strip in the water. You can also test your hands, your gloves or hard hat, a bar or liquid soap, your car or truck seats. An alkali is a caustic material.
Alkalies have a corrosive or irritating effect on living tissue.
Like acids, alkalies burn skin. But alkalies are sneakier than acids. Alkalies damage skin slowly. An alkali such as wet Portland cement can stay on your skin for several hours before you feel the chemical burn. Acidity and alkalinity are measured on a pH scale.