A small amount of water draining after shutdown can be normal. A continuous leak is not.
First, verify the leak source. Check all hose connections for tightness. Ensure the garden hose is not kinked and the faucet is fully on during operation. A restricted supply can cause issues.
If the leak is from the pump seals, the system may have residual pressure. Always follow the correct shutdown: turn the unit OFF, point the spray wand in a safe direction, and pull the trigger to release all water pressure. This relieves stress on seals.
If leaking persists, inspect for physical damage. A guard or other part that is damaged must be properly repaired or replaced by an authorized service center. Do not operate a leaking unit.