In article ,
Derek wrote:

On Tue, 16 Sep 2014 14:01:16 +0100, soup
wrote:

My son has asked me to put a tap in to drain his trough (it is filled
with stones, plants sit on top of the stones and water).


Why not just drill a few drain holes half way up, is there a reason
for a need to have the trough so wet? that way you get the plants
being irrigated, I guess that is its wanted to have some water
sitting in the bottom

OK I'll chip in too: not sure what your son wants to achieve he looks
like a trough of water and gravel, which accommodates water- or
bog-plants, perhaps ... which he wants to drain now and again.

You cannot fit a tap without first emptying the trough: the tap needs to
be fastened securely from the inside.

What I would do is similar to Derek's suggestion above: I'd drill a hole
say 1/2" in diameter *at the bottom edge* (you don't want water sitting
forever in the bottom: it will get very nasty), and I would shove a cork
or something similar in it, to be removed when draining is required. I'd
put the hole round the back, or in the less-seen side.

John