I'm also curious about water in the game. I guess there is enough rain so that doesn't run out , but I find it interesting that there can be a food crisis without a water shortage 
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Well because of sunlight shortage! in my idea of that dark futuristic world, the sky is almost completely enveloped in dark clouds (like Blade Runner) and would be quite hard to raise vegetables (or any kind of lifeform really) without the solar light 
As an environmental chemist and hobby-ecologist, I think I have to answer to the statements.
First, vegetables are not ONLY consuming water, that's why flowers in a pot of water will die rather soon. And plants can prosper in rather shadowy environments, e.g. under the canopy of the rain forest, there is a huge number of plants which do not like direct solar radiation.
Plants need light and water, to produce "sugar" (CHOH) and the oxygen we breath with the following reaction: CO2 + H2O ----(light)----> CHOH + O2
However, as we cannot live from sugar alone, plants cannot either. They need to construct other molecules as well, e.g. the chlorophyll, which is important to 'harvest' the solar radiation. For that reason, plants need a lot of other nutrients as well, e.g. nitrogen and phosphor, and minerals. Soils usually provide these nutrients, as does air. However, a plant cannot take up water and nutrients from the soil easily, therefore, a symbiosis with various types of mycorrhiza fungi has evolved. The fungus gets sugar (see above) from the plant, and returns water and nutrients to the plant, which results in a win-win situation. Interestingly, these mycorrhiza fungi take nitrogen from the atmosphere, although the fungi are coating the roots of the plants which are in the soil. This is possible because healthy soil is more than just "dirt" - it only consists of about 50% of its volume of solid materials, the other half is water and air. The earthworms and other organisms dig channels through the soils (bioturbation) which promote soil ventilation. A soil with a healthy bioactivity and thus high fraction of channels in it also helps in preventing floods, as huge amounts of water can penetrate deep soil horizons easily and thus do not harm the top soil layer, which is important for agriculture.
To close, I think a darker world could actually grow food for humans, but I agree, maybe not for as many as live on it today. With fertilizers and biotechnology, we might help a bit and don't forget, we can always eat fungi, which usually grow very nicely in dark and humid environments (they don't need solar radiation) and a future society can of course synthesize its food from basic chemical elements. It won't be a pleasure to eat, but we would not starve. A food crisis can come because of many factors, not just water scarcity (the current food crisis in the horn of Africa are mainly, but not only due to water scarcity).
Sorry, I spammed this forum, but this complex interaction of natural environment, a wide spectrum of species and physical laws is highly interesting. It forms the basics of our lives and thus a basic understanding might not be totally useless. I can provide more info if someone is interested. Let me finish with a book recommendation: Tim Flannery, Here on Earth:
http://www.amazon.com/Here-Earth-Natural-History-Planet/dp/080211976X/
