There are many occasions when you drink water only with food and from a matching and harmonizing point of view those are the most rewarding setups. The focus can really be on food and water and the wine is not distracting the experience. Below are some rules how to approach the subject.
The 75 Percent Rule
The mouthfeel sensation of the whole dish should be matched with the carbonation level of the water. The mouthfeel generated by the bubbles should be matched with the mouthfeel of the dish. Loud, big, bold bubbles overpower subtle dishes, while Still water might be too great a contrast with crispy food. Bigger bubbles would stand up better to the mouthfeel of such a dish. An alternative epicurean pleasure can be achieved by carefully contrasting the mouthfeel of a dish with a water's carbonation. Sushi with an Effervescent or even Light carbonated water is a perfect example.
The 20 Percent Rule
The dominant food items of the dish should be matched with the mineral content of the water. Low TDS waters have a light, sometimes crisp, perception, while higher TDS levels give the water some weight and substance. High levels of sodium (salt), bicarbonate, and silica (or their absence) can also have some impact on the perception of the water. Use sodium-free water with caviar or water with a high bicarbonate level for cheese. Softer waters (low in calcium and magnesium) with higher silica levels can display a nice sweet softness that works well with some desserts.
The 5 Percent Rule
Fine-tune the drinking experience with the water's acidity or alkalinity. A neutral pH works well with anything. Sometimes a sweet perception is possible in waters with a slight alkalinity, while waters with a very high pH may demonstrate a very subtle bitterness, but never an unpleasant one. Try matching acidic water with fatty food or seafood. The contribution that pH factor makes to food and water matching is easily overrated, only on the outer ranges of the spectrum (less than 5 or more than 10) does it play a more significant role.