Product review (1 stars): Double?  Hardly.  Barely 6 months
Purchased this Waterdrop PLUS DA29-00003G in February, THIS year, 2018, six months ago and I've been needing to replace it since the end of July.  I specifically paid extra ($18 in Feb.) for this one because it alleged it lasts twice as long as the standard, 12 months.  It didn't.  Not my usual brand and will not be a repeat purchase for me.