Water under door thresholds.

[Bob Rowlands]

I see a simple fix thanks to the photo.

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exterior door drip edge sweeps

Check photos in images

I'd think you could buy those online (at the appropriate door width) and have them shipped to your locale? I have successfully retrofitted a few of the extruded aluminum variety with the large curved lip and the integral sweep.

Additionally in your specific application I would bevel the tack strip AND bottom plate that is directly under the center of the door sufficiently such that the drip edge will shed water onto the bevel. That will help keep water from pooling under the door. Also, if you haven't already done it, caulk the seam under the side lites. Good luck.