Yes, it will. You have essentially employed a geowick (... another new word, exclusively for the container forum). ;o) If the clay is saturated, however, it can work against you, as you've created a bathtub effect. The hole you dug could fill with water from surrounding soil & actually create a PWT where there was none.

Al

Al

Thank you!

Fortunately the containers aren't in an area where water stands but are in the first row of our neighbor's plowed field (full of bindweed, so guess why I didn't want to plant the muskmelons directly in that clay soil, even if plowed!). During heavy rains, things might get pretty soggy, but unless we have days and days of rain on end, drainage isn't a problem there because the land slopes toward a creek. The heavy clay underlayment is about 6 inches below the topsoil.

Now, to cross my fingers and see what happens with this "geowick" in place...

Do the same physics principles determine the earth's water table, that underground water supply that our well taps into?

Not always, but water often perches in clay and silt deposited over more aggregate soils (gravel, scree, rocks) - same principle as using a water retentive soil atop a "drainage" layer in containers. The water "perches" in the retentive soil & doesn't drain, so instead of having a saturated layer at the container bottom, you have it near the top, above the "drainage" layer.

Al