If you have a white 10" QMP housing, there will be an o-ring in the base of the housing. This forms a seal when you screw the housing shut.
Water leaks from this section can be caused by:
The Housing Isn't Screwed Together Tightly Enough
Give it another twist to make sure it is on tightly enough. In most cases, the housing only needs to be screwed on hand-tight, but you may need to give it a small tweak with your housing spanner. Avoid over-tightening the unit as you can damage the o-ring.
The O-ring Is Perished Or Damaged
Take a closer look at the condition of the o-ring. If there are any tears or the o-ring looks very flat, it may be time to replace it.
Damage To The Housing
The plastic housing can crack if it has been dropped or massively over-tightened. To see if this is the case, inspect it for hairline cracks.