The problem is the cementatious lime based grout easily absorbs moisture, oils and sugars that in turn attract bacteria, dirt and other solids that change the overall appearance by darkening the grout.

Other porous surfaces like brick, Italian quarry- tile, limestone and other engineered flooring all acts like concrete or grout, absorbing liquids, oils and dirt to a point that their appearance also darkens with time

Floor Cleaning UK hard surface cleaning tools have the ability to do more than dilute and suspend the dirt. The combination of hot water, high pressure, emulsifier and vacuum creates a one step cleaning process.

First the dirt, bacteria and grime is released from its anchoring position by applying an emulsifier. The pressurised water seeks out unwanted grime, bacteria and chemical residues hidden in microscopic pockets within the tile and grout. Finally suction removes the dirty water and leaves the tile and grout clean.