How much coffe is safe to drink?

Maximum is unknown. Moderate coffee drinking is safe, but the maximum safe amount is unknown. Moderate is a vague word, but probably means 3-4 cups a day (24-32 ounces). Heavy drinking is likely 6 cups or more a day, and caffeine can cause unwanted symptoms such as increased blood pressure, increased heart rate, and sometimes irregular heart beats. Caffeine in larger doses is a mildly addictive stimulant.
Oh Boy ! I have not seen, nor heard, nor read....Any coffee related overdose, .... Just coffee I am alluding to.... Leading to death.... Come to think of it ...Neither tea....