I'm about to replace the drain tubes on my wife's V70 as they've blocked and flooded the passenger footwell twice. The first time with 3" of water which required pulling out the carpet and pad and using a shopvac to remove the water. The pad is about 4" thick so it stayed outside drying for a couple of weeks.

Every oil change I run thick string trimmer line down each drain and follow with a mixture of water and bleach until I see water draining below the car and the sunroof catch basin empty quickly.

The second time the drains blocked the tray overflowed into the headliner and down the inside of the windshield. I just got the leading edge of the headliner glued back in place. The foam backing had disintegrated from the water.

No sunroofs (or convertibles) ever again.

Erwin