Leaks from taps and mixers are generally a straightforward repair. The solution will depend on the type of tap you have. Mixers are extremely common in homes these days and can leak due to debris becoming stuck in the cartridge or failed seals. If possible we will replace the cartridge in the mixer however it is often cheaper to simply replace the whole mixer.
A conventional tap that you turn is usually as straightforward as replacing the washer, valve or o-ring in the tap. The washers and valve can wear and harden over time or can be compressed from over tightening the tap. A proper tap should not need much pressure to close off completely.
A tap may also become tight to turn - especially garden taps and external valves due to rust and grime build up. Sometimes the tap itself may be ceased and need to be replaced.
Don't leave a leaking tap too long as it will waste water and money but also if the leak is allowing water to flow into walls or floors it may be doing significant structural damage which can go unnoticed for a long period of time and be costly to repair.