1 Prepare for safe work
Close the main or local valve, open the lowest faucet to release the pressure, and protect the floor with a bucket and cloths. If electricity is nearby, turn off the corresponding fuse.

⚠ Warning: Do not work on a pipe under pressure or on a boiler connected to electricity. A hidden leak, a damaged main line, and repeated wetting of the wall require a plumber.
2 Determine the condition and the cause
Close the faucet and unscrew the hose at the mixer tap and head. If the joint is stuck, protect the chrome with a cloth before using pliers.

3 Perform the key check
Remove the old gaskets, clean the scale from the flat seats, and check if the new gaskets match the diameter of the nuts.

4 Perform the repair or maintenance
Position the gaskets and hand-tighten the nuts; Teflon tape is usually not required on a joint sealed by a flat rubber gasket.

? Tip: Photograph the initial state and change only one thing at a time. This will make it easier to determine what really solved the problem.
5 Test the result
Slowly turn on the water and observe each joint for at least a few minutes, first without load and then at full flow. A wet trace, a drop in pressure, or a sewer smell means that the joint needs to be inspected again.