Finally, sodium hydroxide is added to adjust the final pH/alkalinity, sodium hypochlorite for disinfection and fluoride for fluoridation. This process is often used as a pre-treatment method while another processes, such as reverse osmosis, is used for the final treatment.[10] A disadvantage of this method is its use of chemicals, such as ozone, flocculents, hydrogen peroxide, lime, and chlorine for the filtration process.[10] These chemicals could be dangerous if used incorrectly or if they remained in the water after complete treatment. This requires special precautions, and each step of the process has to be controlled to achieve an overall optimal performance.[10] The need for a complex control system for conventional treatment can result in it being financially costly.[10] This has led to the development of alternative pre-treatment and treatment methods for raw water.