Has anyone tried washing their XZ with water?

I already have, since it's a water proof phone.. I'm currently experiencing my volume speaker going very low compared to what it was before.

So is this normal & will get better with time? or the phone doesn't guarantee the speaker being water proof with it?
Kindly let me know, I was pretty sure that all openings (charger, SIM slot, headphone jack etc.) were tightly shut.

PS. I have dried my phone afterwards too, same result.

 

after giving my phone sometime to dry up more, the speaker is back to normal.