The other poster's comment, above, is not with regard to safety but rather temperature of the cold water available when this system is used.
In our home we have hard water and thus have a water softener. I have never cared for the taste of softened water for drinking. Will I occasionally take a drink to wash down an aspirin? Sure. Will I use it several times per day to "brush and flush?" Yep.
With the Watts recirculator installed, I have one additional reason not to drink it and that is that the first glass of "cold" water comes out lukewarm to warm. Not hot.