The Senate is considering various ways to pay for a health care system overhaul. One option is to start taxing things that are contributing to health problems such as obesity, and sodas are in the cross-hairs.From The Wall Street Journal:"The Center for Science in the Public Interest, a Washington-based watchdog group that pressures food companies to make healthier products, plans to propose a federal excise tax on soda, certain fruit drinks, energy drinks, sports drinks and ready-to-drink teas. It would not include most diet beverages. Excise taxes are levied on goods and manufacturers typically pass them on to consumers."The idea is that a new tax would discourage people from drinking so much soda, and thereby contribute to a healthier America, all while raising new revenue to improve health care. The Congressional Budget Office estimates that adding a $.03 tax to every can of soda would generate $24 billion over the next four years. It's a relatively small amount, but it would help.So why not? According to the Journal, "the lobby that represents Coca-Cola, PepsiCo, Kraft, and other companies said such a tax would unfairly hit lower-income Americans and wouldn't deter consumption."The lobby is probably arguing that, because lower-income Americans drink more soda, they would therefore end up having to pay more, and so the tax is unfair. But that argument only works if they don't have alternatives. In fact, people in every income bracket have access to tap water, which also happens to be both freer and healthier than soda.Would you support a soda tax?Photo from the Freakonomics blog.