From the 6PM press conference by TEPCO on April 4, 2012 (archived on TEPCO's website):
1.6 x 10^0 becquerels/cubic centimeter of tritium was detected for the first time in the water of the deep well.
The level is about the same as that of tritium being detected in the subdrain pits.
The well is located at about 500 meters west of the reactors, elevation 30 meters from the sea level, and 20 meters higher than the reactor buildings.
Groundwater flows from west to east, so it is unlikely that tritium was from the contaminated water in the reactor/turbine buildings.
I haven't found the data from TEPCO on their site yet, though Matsumoto said it had been published.