I really like the refreshing taste of San Pellegrino, but dislike that this water is bottled in Europe, shipped over water and delivered to me in Milwaukee, where we also have water. San Pellegrino costs about $1.75 per liter, and comes in recyclable bottles. The homemade version I’ve been making for the last four months costs less than one penny per liter, and is made in my kitchen in reusable bottles. The cost of the equipment was less than $150, which paid for itself after I’d carbonated my first 100 liters of water.
The equipment required is relatively simple: An aluminum tank that contains 5Lbs of CO2, a gas regulator, a hose ending with a locking Schrader air chuck, a plastic bottle, a bottle cap with a Schrader valve stem mounted in it and two hose clamps. All of these items are visible in the photos below.
The aluminum tank and gas regulator are available locally at restaurant or homebrew supply stores, or online from places like beveragefactory.com or coppertubingsales.com. Prices at these latter two places are $85 – $100 for the pair. I filled the CO2 tank for $9 at a local beer retailer. I purchased the locking chrome plated air chuck, the stainless steel hose barb connected to it, the hose clamps, and the steel wire reinforced hose from a local hardware store for $15. The Schrader valve stems were purchased from a local auto parts store – they are fully chrome plated, and are sold as replacement car tire valve stems for $2 each.
I initially used standard industrial air hose fittings instead of Schrader valves, but ran into several problems. Only one side of this type of fitting seals when the mating fittings are disconnected. This means that after a liter is carbonated and the hose is detached from the plastic bottle, either all the CO2 in the hose leaks out, or some of the CO2 leaks out of the bottle. Also, inexpensive industrial air fittings are either made of steel or bronze and begin to corrode due to exposure to the carbonic acid formed when the water is carbonated. Chrome plated Schrader valves have neither of these problems, and are even less expensive than industrial air fittings.
The carbonation process is also simple. I fill a plastic San Pellegrino bottle 80% to 85% full of Brita filtered water chilled to ~36 degrees (standard refrigerator temperature), I squeeze all the air out of the bottle and tighten the plastic cap with the Schrader valve onto it. I fully open the CO2 tank valve, set the gas regulator valve to 55 PSI (typical commercial waters are carbonated to about 20 PSI), squeeze the locking Schrader air chuck, and lock it onto the bottle. CO2 immediately begins to flow, and inflates the bottle instantly. An audible hiss continues as the CO2 pressurizes the bottle, which I shake vigorously for 20 to 25 seconds, after which time the CO2 hiss has stopped. The hose is then disconnected from the bottle, and the water is carbonated!
All these details are important to successful carbonation. The empty space in the bottle (the 15% to 20% of the bottle that doesn’t contain water) is critical to allowing the CO2 to get and stay in suspension. The amount of CO2 that is soluble in water increases with colder temperatures. Squeezing out all the air allows for more CO2 to fit in the bottle. Shaking the bottle increases the rate at which the CO2 dissolves in the water. All of these factors make for more fizzy water (which is the goal, right?)
The taste of San Pellegrino can be more accurately replicated with the addition of minerals. With the addition of 1/8 tsp of Magnesium sulfate (Epsom salts) and 1/8 tsp of calcium chloride, one achieves the 210mg/L of Calcium and 60mg/L of Magnesium that San Pellegrino has! Both of these minerals are wine/beer brewing additives, and can be purchased from local homebrew supply stores. Check here for more mineral additive possibilities, and the book “The Good Water Guide” for the mineral composition of most commercial waters on Earth. I find that carbonating to 55 PSI rather than a more reasonable 20 to 25 PSI makes for so much more joy that I (and my kidneys) don’t miss the extra minerals.
If you want to make this setup at home, please follow these safety guidelines. There are several which are very important, as a gas cylinder is somewhat dangerous, as its internal pressure is between 700 to 800 PSI, depending on temperature. Carrying the cylinder by its valve is a bad idea. The tank should be secured at all times so it doesn’t tip over and damage the valve. When it is transported, it should always be upright and it shouldn’t be left in a car sitting in the sun, as the internal pressure will increase hundreds of PSI. The regulator you purchase should have a pressure safety valve which releases at ~60 PSI to vent excess pressure and prevent your plastic bottle from exploding. Similarly, your hose should be rated for higher than the pressure you intend to carbonate to. You should never carbonate in glass bottles.
I measured the pH of my 55 PSI carbonated water, and found it to be 4.6, whereas the pH of Coke is a much more acidic 3.2, as shown below. The pH of my water prior to carbonation was a perfectly neutral 7.0.