In the process of reverse osmosis, water is pushed through a semipermeable membrane. This purifies the water by removing minerals, chemicals, and larger particles like salt. In places where fresh water is not widely available, reverse osmosis can be used to purify seawater. Reverse osmosis systems are usually used in developed communities that have the infrastructure to support the system over the long term. LDS Charities has installed several reverse osmosis systems in India to help communities filter out high concentrations of fluoride, which can cause health issues if consumed in high quantities.