How do you determine if your well has run dry

Ok, in the summer heat (daytime) we could tell because the pipes would make a 'clanging' noise from the pump moving a lot of air with very little water. Then overnight the water table / ground water would 'recharge' and we'd have water again in the morning. Just had to adjust the usage - or dig a deeper well!

Just a little tip for this site - the more info you can give in your question, the better. Vague just doesn't give us much to go on.