In Jainism, the main reason potatoes (regardless of how they are grown—whether in soil or in water) are generally not considered suitable for consumption is due to the principle of ahimsa (non-violence). Potatoes, as well as other root vegetables like onions, garlic, carrots, and radishes, are avoided for these reasons:

1. Multiple Life Forms: Jain philosophy teaches that root vegetables contain an infinite number of microorganisms and tiny life forms within them. When uprooted or harvested, many living beings are killed, causing greater himsa (violence).

1. Destruction of the Whole Plant: Consuming root vegetables involves uprooting and destroying the entire plant, whereas harvesting fruits or leaves does not kill the main plant.

1. Potential for Microbial Growth: Root vegetables—whether grown in soil or hydroponically (in water)—still develop underground or beneath the surface, harboring many life forms. The water does not eliminate the presence of microorganisms or the ethical concerns about killing the entire plant.

Therefore, even if potatoes are grown in water, the fundamental issues of destroying the whole plant and causing harm to multiple living beings remain. For these reasons, strict Jains avoid consuming potatoes, irrespective of the growing method.