The Water Shippers control the majority of water concessions across Arrakis through a network of dynastic holdings, including the Bewts and the Yafengs, who maintain a coordinated front even as they compete for influence behind it. They are not a House, though they behave like one when it suits them.
Their strength lies in infrastructure: ice quarries at the polar cap, dew fields in the lowlands, and a distribution network that reaches every settlement worth taxing.
Primary leverage: scarcity. They ration water to create dependence, then sell relief at escalating margins.
Primary weakness: labor. Slave stock. High turnover. Nowadays, not so easily replenished. Rising cost.
Recommendation: exploit, do not trust.
Water is power. There is no reason it should remain in their hands.