Self watering bucket
I drill a 1-1/4 inch hole in the bottom middle of a bucket.
I make a wick using netting & sphagnum moss about 12" long, a 1/1/2" diameter cigar.
I stick the wick 4" into the bucket & fill the bucket with soil.
The water bucket:
I drill a 1" hole (bottom of the hole is 8" from the bottom of the water bucket) so I can add water.
I put a heavy duty flower pot, 8" tall one, in the bottom,
fill it with water to the top of the flower pot, (it starts running out the fill hole.)
Set the soil bucket in the water bucket.
There is over 2 gallons of water in the bottom bucket lasts about 2 days for a large plant on sunny days, about 3 day on cool cloudy days.
I notice the roost grow down the sphagnum moss wick into the the water bucket for tomatoes.
Soil mix, I mix about 3/4 to a gallon of perlite with the soil. If I use "Pro mix", I add about another quart of perlite.
You can even mix plant food with the water but about 1/4 the strength as the plant is mainlining the water.
Another type is a false bottom bucket
Same wick as in above Sphagnum moss 12" cigar
4" from bottom I drill a 1" hole
drill some holes for wire just above the water hole to support a false bottom
1" hole in the falss bottom (center) for the wick.
Put in the false bottom, add the wick then add soil.
I have added a level float water level indicator
I use a piece of 3/4" pvc, & make a thin piece of blue board styrofoam float that slide easy inside the PVC. I fill the bucket & mark where it is full & empty. It floats up as I fill the bucket water chamber.
For tomatoes I put some stakes in the bucket before I add the soil to tie the tomato to.
You can use a long piece of sponge or anything that wicks water. I like the moss because the
roots grow into it & mainline water. (helps in a GH on hot days)
You could use a tub that holds several buckets & just keep the tub full of water & set several buckets just above water line with the wick in the water. You could make a 2X6 or 8 --- 8 foot long box & line it with plastic to hold water. Many ways to self water so you can leave for a few days & go fishing.
Some I've put a 90° pvc elbow in to make it easier to add water (pic)
My self watering design
Check out my very simple but effective design. Jim's Alaska Grow Buckets. Free .pdf instructions at http://chateau-listeur.blogspot.com/2011/06/alaska-grow-buckets.html