vat, tub, tank
槽 centers on a large container for holding liquids or solids: a vat, tub, or tank.
槽 combines 木 (wood) with 曹, which likely contributes the sound. The character originally referred to a wooden trough or container.
The left side is wood 木, and the right side 曹 looks like a container with a lid and internal divisions. Picture a large wooden tub or vat made from planks.
For ソウ, imagine a soul (ソウ) being stored in a wooden vat: soul -> ソウ, and the vat holds it.
water tank; cistern
basin; tub
body (of a biwa)
bathtub
water-purification tank
(dental) alveolus; tooth socket
one-part washing machine
main bath (i.e. in a bathhouse)
two-part washing machine
tub used to collect feces in an outhouse
water tank
wooden vat (esp. for sake brewing); wooden tank
(sake) brewed in wooden vats, squeezed out by weight on a pole
alveolitis
periodontitis; pyorrhea; pyorrhoea; pyorrhea alveolaris; inflammation of the gingiva (gums) resulting in bone loss
alveolar bone
tank truck; tank car
precipitation tank; settling tank; sedimentation tank
oil tank
washing machine tub