The correlation of water to energy, food supplies, and prices is explained through the general connection between them. Water by itself is a cost factor, and the lack of it makes that cost rise. However, water is also essential to the production of power and energy, whether the base is in renewable energies or fossil fuel run power plants. And in the same respect, water is vital to the supply of food as it is important to both plants and animals.
Water in energy is due to the fact that water is converted to steam, and steam is used to power most turbine run generators, which supply power in the form of electrical energy. This water is used in processes that involve coal burning facilities, nuclear power plants, geothermal power plants, hydro-electric processes, and others. With the exception of hydro-electric power plants, other power facilities that use a heat well to produce steam will siphon their water supply from rivers or lakes, boil it to evaporation, pump it through their turbines, and bleed the steam off into the atmosphere through cooling towers. Other waste waters in the form of heat siphons are pumped back into the lake or river at slightly higher temperatures than what was pulled out. This action increases the heat of the water body and increase the surface evaporation rate in warm regions.
Water to agriculture and farm life is vital to the plants and animals that rely on it to survive. A lack of rain or steady supply results in irrigation that requires the removal of water from one source in order to satisfy the needs of another, often requiring a certain cost to transport it, whether through pipes or channels. Water that can't be drawn from the wells that once supplied them is much more expensive than water that is there. As for the amount of water that is wasted in the entire irrigation process, that is just more water that doesn't return to the cycle.
Then there is water itself. Water is the main source of life to billions across the globe. Whether that water is to drink, water pets, water gardens, plants, lawns, wash themselves, wash cars, etc, etc, water is a valuable commodity that only continues to get stretched thinner with every passing day. In times of drought, lack of water raises prices of foods and electricity. In times of flood, water destroys farmland, urban areas, and many more places, also raising prices from damages and shortages.
With other costs and prices focused on the transportation end of things, water is simply the key element. When there is a lot, prices will rise in some ways, but fall in others. When there is too little, water related prices will rise, as will others, yet still have something falling. With hot and cold factors as well, there is nothing that water doesn't touch in the world market of everything.