Good question, Kay. Without a water analysis, it is hard to say what is in the water from the city. However, I’m sure the mineral availability is covered by adding forage (pasture and hay) plus a mined salt block. This comment is based on humans living on treated water and not having mineral deficiencies.

I need to state here my position on minerals. Minerals are used in processes the body needs to live. For example, we all know that iron is incorporated into the protein hemoglobin to attach an oxygen molecule to carry oxygen to the parts of the body (everywhere) for metabolism. Another example is calcium used in muscle contraction. Calcium stored in bones uses the endocrine system to regulate and maintain adequate blood supplies. Because of the importance of minerals in preserving life, they are tightly regulated through a chelation system. In my mind, I see a “mineral deficiency” as actually a protein deficiency.

Amino acids (the building blocks of proteins) are the primary ligand that chelates to minerals that allow their absorption through the gut wall. So in essence, if the body needs a mineral, it sends an amino acid into the gut to attach (chelate) to the mineral. Otherwise, the mineral just passes through the body. Chelation is how we don’t get an excess of minerals. So a deficiency in protein in the diet would possibly cause a deficiency in mineral absorption.

In addition, most minerals recycle in the body, such as iron. Others are lost in sweat and need replacing; the salt lick or added electrolytes will provide for this. Excess consumption of calcium and phosphorus caused by adding dicalcium phosphate in grain mixes will suppress magnesium absorption, leading to a magnesium deficiency. Feeding grains without dicalcium phosphate will suppress calcium absorption leading to Ricketts disease (softening of bones and coma and death).

Luckily, forage and mined salt licks provide most minerals. Water is an additional source if coming from the ground. City water may be treated with minerals; an analysis will show this. I am still looking for mineral deficiency cases in horses, other than starvation or “thumps” in heavily exercised horses. I see, however, vastly improved horses (hair, hooves, behavior, etc.) in horses off inflammatory ingredients plus high-quality protein. So I am not too worried about using city water in correctly fed horses.