"When you add water to a shop-bought shampoo, the pH level does go up slightly but only by about 0.5 points. However, this can depend on the pH of your water wherever you live.  It is important that the pH of the shampoo that we use stays in the 4.5-5.5 range for optimal scalp health and also to be able to effectively remove residue, bacteria, and other particles. Therefore it is recommended to test the pH after diluting the product. If the pH is unbalanced you can rebalance it with some Citric Acid or Lemon Juice!"