| You have to have a problem with either packing or o-rings inside those valve stems, as stated in my previous post.
It is not an installation problem on your part nor a washer or seat issue as then, if it were, the water would continue to drip out the spout after you shut the handles off. And you have never said it does THAT. So I advise you disect the valve stem to make sure there is either packing inside with a nut tightening down the packing or that you have to tighten down a threaded nipple inside the nut (on the outer end of the nipple is where a chrome trim ring, called an escutcheon, screws on), or o-rings, depending on your type of stem.
In a nutshell - could be one of three things depending on your make of valve stem: Either you have an o-ring(s) inside the two halves of the stem that create the seal, or you have a smaller nut around the stem that when tightened makes some packing crush more against the stem, or it also relies on that nipple, that slides over the stem and then screws into it, to push against packing.  |