Widely spread of chemically industry producing many types of environmentally pollutants (e.g dyes, herbicides, pesticides, insecticides, drugs, bacteria and others), most of these pollutants reach our drinking water resources, different strategies have been followed to purify contaminated water, one of the low-cost technology is based on using semiconductors as catalyst for photodegradation of water-organic contaminants. TiO2 nano- and microparticles have been used for photo-degradation of widely spread water organic contaminants. Due to its wide bandgap (~3.2 eV) TiO2 photocatalytic activity is limited to shorter wavelengths only (UV region). As only ~4% of the solar spectrum falls in the UV region, smaller bandgap semiconductors (e.g. CdS, with 2.3 eV) are used to sensitize TiO2 particles. The TiO2/CdS system has been used as a catalyst in water purification by photo-degradation of organic contaminants such as methyl orange and Phenazopyridine (Medically active compound). However, the TiO2/CdS system is unstable under photodegradation conditions yielding hazardous Cd2 ions. Alternative ZnO nanoparticles naked and substrate to different materials like (clay, sand, and activated carbon) were used in photodegradation process also natural dyes (anthocyanin & Curcumin) were used as a sensitizer for the TiO2 nanoparticles. The different prepared nano-catalyst systems were used to photo-degrade various contaminants of water and soil, such as methyl orange, phenazopyridine, paracetamol, phenols, and halo-phenols, with solar radiation. Different reaction parameters (such as catalytic efficiency, effects of catalyst concentration, catalyst recovery, contaminant concentration, temperature, pH and complete mineralization) will be discussed together.