It is important to carry out maintenance on a single-handle faucet for its correct operation, also because this type of faucet has mostly replaced the classic screw faucets found in domestic bathrooms. Instead of a screw with gasket, it has a “cartridge” which, actuated by the handle, mixes and dispenses water. The “cartridge” is cylindrical and is made of plastic or ceramic material. It has various inlet and outlet holes that allow the mixing and delivery of hot and cold water depending on the movement and positioning of the handle. Each faucet model uses cartridges of various sizes and structures depending on the manufacturer, but they all have the same operating principle.
The cartridge is also subject to faults: it may no longer allow water to pass through, or it may not mix well, or it may only allow hot or cold water to flow out. If the cartridge is severely damaged it cannot be repaired, and must be replaced with an equal one. In any case, you’ll need to access the interior of the faucet.