Carbonating at Home

I like making my own tonic syrup for gin and tonics, but found keeping fresh carbonated water on hand a pain. I already had a CO2 tank with a regulator for a keg I keep in the basement fridge. I read about a special "cap" you can purchase and a quick-connect hose for the CO2 source.

I hooked everything up and used some speny plastic soda bottles I'd been saving. Filled the bottles with water up to about 6 inches from the top. Chilled them and put them in freezer for a while to get the water as cold as possible. Water temp and CO2 solubility are inversely proportional if I recall correctly.

Followed directions adding CO2 at about 40 psi and shaking like crazy. Product delivered. Removed special cap and put original cap on the bottle and left in fridge.

I'm planning to make my own ginger beer and carbonate it using this setup (Morgenthaler has a recipe for ginger beer). Or just make ginger syrup and adding carbonated water. Kevin Liu has a suggestion to add tincture of cayenne to substitute a longer lasting component of ginger that degrades quickly. 

Anyway, this works well and discounting the labor, comes out pretty cheap for carbonated water. 

Thanks to Kevin for improved technique. He posted on Serious Eats and has excellent suggestions.