On Fri, 09 Jan 2015 22:09:42 -0600, Kate wrote:

I find it hard to believe that it could have been three faulty flappers.

I've installed new flappers plenty of times. Once, I did not get one
on correctly and it leaked. Just a little tinkering and adjustment
fixed it.

When you think a flapper is bad or leaking, add few drops of food
color in the tank and allow it to sit over night. The bowl water will
change color.

If the tank keeps running while you're present, the flapper may not be
closed - you can often see ripples in the bowl water as the water
exits the bowl rim jets.

Glad you got things fixed and thanks for the follow up.
--
Definition of a camel: A horse designed by a committee