In converting hardness, how much does 1 grain/gal equal in mg/L?

In water treatment, converting hardness from grains per gallon (gr/gal) to milligrams per liter (mg/L) is a common calculation due to the different units of measurement used in various contexts. The conversion factor for this specific scenario is based on the weight of calcium carbonate (CaCO3), which is used as a common standard for expressing water hardness.

1 grain of hardness is defined as equivalent to approximately 17.1 mg/L of CaCO3. This calculation is critical for assessing water quality, determining treatment needs, and understanding the scale deposition risks in systems handling water.

Using this conversion factor, you find that for every grain of hardness measured, the equivalent concentration in mg/L is approximately 17.1. This value is widely recognized in the water treatment community, making it the correct conversion for the question at hand. Therefore, when asked how many mg/L correspond to 1 grain/gal, the answer is 17.1 mg/L.