Mozzie mystery

I live in Midland, with deep sewerage; yet, every night one mosquito gets through my defences.

This one mozzie stops me going to sleep, by zzzzzzzz’ing about my ear, turn on the light, and it hides, light a mosquito coil, and I find that it has bitten me, so the itch stops me sleeping.

I know of no open water, so where can they breed? Do they use our stink pipes? Is there an advanced mozzie school, where juveniles are taught to break into houses, and create the greatest amount of sleep deprivation?