Ash in cat food is the inorganic mineral content left over when the organic portion of the food has been cooked. There was some confusion about ash content in pet foods a few years ago when people mistakenly believed it might be a cause of Feline Lower Urinary Tract Disease (it isn't). There are many causes, the two primary reasons being the pH of the urine and the amount of water cats drink. 

Ash is part of the food. The percentage of ash indicates the amount of minerals. Our dry cat food should result in urine with an average pH of 6.2, which is normal. 

Anyone who is concerned about the water intake of their cat should consider feeding either Instinctive Choice All Life Stage Cat Food or Pork & Duck Grain-Free Recipe, as well as one of our all life stage kibbles for cats.