Why would new plumbing fixture leak?

I had a new water control valve installed in my upstairs shower. From time-to-time I hear water drip out. It's only a few drops, then stops. I put a bucket under the shower head for an entire day & the total amount was insignificant. Even so, the leaks shouldn't be happening on an all new system, after all, the 25 yo valve that was removed didn't leak, at all. Also, this happens even if it has not been recently used. I don't know where or why the water is coming out. Yes, it is all the way off, & after it was installed the internal washers were cleaned.

Artist2012-08-28T20:12:19Z

Favorite Answer

did bad job plumber

?2012-08-28T16:50:40Z

Hi, S. If this has been happening ever since the work was done for you, I'd sure consider calling the plumber to "finish" the job at no charge. Yes, it should be off except those few seconds after use.

It's possible that there's a defect in the valve, but not likely. I suspect some tiny bit of debris is preventing a seal from working properly. A dissasembly and very close inspection may reveal that. Sometimes just this process of refitting can cure a drip or leak, even if one doesn't find a "cause". Like a gas line bubble leak check - take it apart and refit, then check again, etc.

Finished installing a new kitchen sink, faucet & sprayer, strainer basket, garbage disposal, supply lines, quarter-turn stops, and all the drain fittings underneath late the other night, fired it up, no leaks, nice and tight, went to bed. Next morning making coffee, realized I had the hot and cold lines reversed. Sigh.

?2016-02-27T18:15:51Z

It's probably Chinese crap!