A leaking monobloc tap can be repaired using a screwdriver and a wrench. However, monobloc taps are unique because they use a ceramic cartridge, rather than a rubber washer or ceramic disc. These cartridges may be different depending on the monobloc tap design, and a replacement may have to be purchased from a hardware store or manufacturer.
Monobloc refers to the type of tap in which a single handle controls the temperature and rate of flow. To repair this kind of tap, first remove the central handle structure. The casing of the tap can usually be removed using a screw located on the base of the cover, a bolt or nut located on the top of the tap or a nut beneath the sink. Once the handle and tap cover have been removed, the valve or headgear of the tap should be exposed. Using a wrench, remove the ceramic cartridge from within the valve. Check the cartridge for any kind of wear or corrosion on the main body. Also, check the rubber seal on the bottom of the cartridge. If there is no visible damage to the cartridge itself, then simply clean the cartridge thoroughly and reassemble the tap. If there is damage to the cartridge, then purchase and install a new one.