Improper venting.
If the drains are truly clogged, there will be no breeding in them as no one will be able to fit in. If there are gaps and you find people breeding there, clog the drains even more.
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Drains are clogged
It was initially a very expensive process, but now, due to the recent flash floods. It is sometimes due to clogged drains. If one day, the drains are totally clogged. Limited water would be able to pass through the drains.
No, generally hair extensions will not cause clogged drains. If your extension comes out and goes down the drain, that might. Generally hair extensions are weaved into your hair and it shouldn't be a problem.
They share the same drain and it is becoming clogged. Drain cleaner in both drains should help.
Sunroof drains are clogged.
The best way to repair clogged drains is with professional draino. You can also use a plunger or a snake to unplug it. You can find everything you need at your local Home Depot.
Partially clogged drain line.
Check for a clogged air gap (the pipes that run from the large drain pipes to the roof of the house).
Don't get hair down them and flush them with a sink full of hot water once a week
Yes, there are 4 drains at each corner of the sunroof which sometimes get clogged.