Our public health relies on wastewater management to treat sewage and remove pollutants coming from our homes and businesses. This system is fundamental to protecting our health. In California, treated wastewater also is a critical source of water for the environment, and, increasingly, a source for recycled water. Climate change is worsening water scarcity and flood risks. Advancements in engineering and technology can help prepare wastewater agencies for a changing climate. But significant shifts in policy and planning are needed to address these challenges. Wastewater agencies must reliably remove pollutants even as the quantity and quality of the water they treat declines during droughts, and when large storms push their equipment to the breaking point.