/zink/ for "sink"--How widespread?

[Gerald Cohen]

   I've received the following request for information: How widespread
is the pronunciation of /zink/ for "sink" (where dishes are washed)?
A lady had been sharing a room in the local hospital (Rolla,
Missouri), and her roommate (from the Ozarks) several times told her
husband where to find a certain object "It's near the zink."  The
lady who heard this in the hospital says she's also heard /zink/ for
"sink" from other people in the Ozarks.

Gerald Cohen