Hair is primarily made of protein, so it makes sense to eat protein-rich foods if you’re trying to maintain healthy growth. Without adequate protein intake, the body can't efficiently make new hair to replace the hair that's shed. That said, eating a steak every day isn’t going to help you. High-fat diets result in increased testosterone levels, which have been linked to hair loss—so steaks are not among the foods that prevent hair loss. Stick to leaner proteins such as fish (which has myriad health benefits beyond just maintaining your hair), chicken, soy products, low-fat cheese, eggs, almonds, beans, and yogurt.
"Hard" water is typically defined as water that has a high mineral content. While large amounts of calcium are often to blame for the development of hard water, high stores of copper and magnesium can also contribute to poor water quality. It should be noted that laboratory experiments have concluded that there was little appreciable difference in the tensile strength and elasticity of hairs after they were treated with hard and soft water.  Anecdotally, however, water with a high mineral content might make your hair feel drier and more brittle, which can contribute to hair loss. If this is your experience there are some steps you can take.