After our large Keurig stopped working after 2 yrs (and the one before that lasted 2 yrs), we decided to go back to the small single serve model..the new K15.  Had to make a run to Starbucks again this morning as it stopped working...long story short after much testing...it continually put out only a fraction of the water put in...for instance adding 8 ounces of water yielded 3 ounces in our cups. About ready to give up on Keurig!