What could be causing occasional air in our water pipes? We have a well and recently every once in a while when we flush a toilet or turn on a faucet, air comes out with the water.

One of several things might be happening.
(1) You have a small leak in the suction line and you're pulling air.**OR**
(2) The water table has been lowered and the pump's cavatating, pulling air instead of water. Any way you look at it your pumps pulling air and that can only happen in the suction section and that's what I'd check first. Good luck, Tom

In addition to speedball1's comments, you should also have someone check the Y joint in the pump line (in the well)... if its old, it could be rotting and in need of replacement...

You should also have someone check your pressure tank. If air is getting that far through your system, the pressure tank itself might have an issue.

How much air are we talking? A quick sputter or does it take a min or two to completey clear it?

in addition to speedball1's comments, you should also have someone check the Y joint in the pump line (in the well)... if its old, it could be rotting and in need of replacement...

you should also have someone check your pressure tank. if air is getting that far through your system, the pressure tank itself might have an issue.

how much air are we talking? a quick sputter or does it take a min or two to completey clear it?
The air does not stop until I turn of the hot water

the air does not stop until I turn of the hot water
Then that would put the focus on the hot water heater. If the heater cold water supply's the first branch the air could have got in the tank through the cold water supply. Back to checking the pump. Regards, Tom