Based on the provided reference, the document gives a brief advice stating that fabric painting "requires much more of paint than regular painting on paper". Although it doesn't directly explain how to mix fabric paint with water, we can infer that dilution with water is possible, but should be done judiciously to avoid compromising the paint's opacity and binding ability to the fabric.
Without more specific information on how to dilute, the best general guidance is to add water very sparingly and test the mixture on a scrap piece of fabric to assess its consistency and color before applying it to your main project. If you add too much water, the color will be too light, or the binder in the paint could be diluted too much to properly adhere to the fabric.
