OptiPure OP or BWS reverse osmosis systems do not “waste” any water! They have a reject stream going to the drain that is required to wash away contaminants removed by the membrane. This is the cost of producing optimized water for your application and is the most cost-effective and reliable method to remove Total Dissolved Solids (TDS) such as chlorides, sodium, calcium and sulfates from ingredient water. With many of the OP and BWS systems, the amount of water “rejected” can be adjusted to maximize efficiency.