It is pretty hard to overwater sod…how long and how frequently are you watering it?  Feeding during the high heat of summer in going to do more harm than good. You want to let sod stay tall while it gets a root system established…like 5″ tall and mow no lower than 3.5″.  This helps keep the roots from dying in hot soil…the longer blades provide shade for the shallow roots below.  You can call any of our stores for advice…HERE are their phone #s or email me at peterb@hewitts.com.