Wastewater from toilets and bidets that requires intensive chemical and biological treatment before it can meet potable standards.

Rainwater harvested from rooftops and impermeable surfaces that is stored in cisterns for municipal drinking water.

Domestic wastewater from washing machines, showers, baths, and sinks that can be reused for non-potable purposes like flushing toilets.

Brackish groundwater extracted from deep coastal aquifers that must undergo reverse osmosis to reduce salinity levels.