As an expert sommelier and brewer, I can confidently say that yes, you can fill a keg with water. In fact, it is quite common to do so when you're not using the keg for its intended purpose, such as when cleaning or testing the keg system.
To fill a keg with water, you will need to follow a few steps. Firstly, ensure that the keg is clean and sanitized. This is important to prevent any contamination or off-flavors in the water. Thoroughly clean the keg using a keg cleaning solution and rinse it well with water.
Next, attach the keg coupler to the keg. The keg coupler is the device that connects the keg to the gas and beverage lines. Make sure it is securely attached to the keg to avoid any leaks.
Now, it's time to fill the keg with water. You can simply use a hose or a water source with a spigot to fill the keg. Place the hose or spigot into the keg's opening and turn on the water flow. Be careful not to overfill the keg, as it may cause spillage or make it difficult to seal the keg properly.
Once the keg is filled with water, it's important to pressurize it to maintain the water's carbonation level. This is similar to how soda or seltzer water is pressurized in a keg. Connect the gas line to the keg coupler and adjust the pressure to the appropriate level. Most seltzer water will require around 30 to 40 psi of pressure.
It's worth noting that when using water in a keg, you'll need to use longer beverage lines to handle the higher pressure. This is because water, like soda or seltzer, requires more pressure to dispense properly. Using shorter lines may result in excess foaming or difficulty in pouring the water.
Filling a keg with water is a straightforward process. Clean and sanitize the keg, attach the keg coupler, fill the keg with water, and pressurize it to maintain carbonation. Remember to use longer beverage lines to handle the higher pressure.