Is water chestnut (singhara) farming profitable and what does it cost to start?

Water chestnut can be profitable on ponds and waterlogged land that would otherwise earn nothing, and the cash costs are relatively modest, mainly planting material, pond preparation, any lease for the water body, and labour, with harvest labour being the main recurring cost since picking is repeated by hand through the season. Income varies with yield, water management and the price, which is seasonal, so no single figure is reliable, and being perishable when fresh, selling quickly or drying for singhara flour helps. It is a traditional, relatively low-input crop suited to those with access to suitable water bodies and the labour for harvesting. Plan your market and any pond lease before starting. Verify realistic per-unit costs, yields and current fresh and flour prices for your area with your KVK and local mandi.