They stay around my upstairs windows sometimes and it's often because the guttering needs clearing out - i don't know if they actually ARE attracted to wet areas but i know i can't do anything about the ones here - worse luck.
I've had them around for a couple of weeks now :-/

I think they are attracted to damp areas or water - is there any stagnant or standing water nearby? This time of year, though, they tend to hang out in areas which are sunlit, same in autumn, but the presence of water nearby, specially stagnant water, means more of them.

We regularly get small clouds of them, don't seem to be a problem... I think thy just enjoy basking in the sun as we do.

The drainpipe in and of itself shouldn't be a problem, but it might mean that its broken somewhere, or that its blocked.

If the midgies like you and love bitting you,one thing that works to stop them bitting is
Skin so soft original dry oil body spray FROM the make's Avon

I use Skin So Soft and it works quite well. Better than some other insect repellents.

Did you know the military issues Skin so Soft as an insect repellant? Makes you wonder what is actually in it - given it is meant to be good for your skin!

I wonder if the makers know it 's used as a insect repellant

Oh yes Avon is well aware and promotes as such now...