Manual coffee machines require manual effort to press hot water into the coffee grounds. Automatic machines use electric drip and do not require the user to press the water. Manual machines need preheated water, while automatic machines warm the water during the brewing process.
When using a manual machine, the coffee grounds are added to the bottom of the press. Hot water is then poured on top of the grounds. French presses are the most common type of manual machines and require the user to physically push the plunger down to press the water into the coffee grounds at the bottom of the press. This pushes the coffee grounds to the bottom and allows the brewed coffee to rise through the mesh screen or filter. This manual process should take approximately 20 seconds as there is resistance when pressing the water.
Electric drip coffee machines use electricity to heat a warming pad. Cold water is then filtered through aluminum tubing wrapped around the warming pad. The warm water is then automatically dripped onto the coffee grounds and through the filter to create the brewed coffee. Automatic machines often make two to four cups of coffee at one time. This is up to twice as much as the average French press.