The Oakland wastewater treatment plant offers tours open to the general public: https://www.ebmud.com/wastewater/collection-treatment/wastewater-treatment-plant

The Oakland wastewater treatment plant offers tours open to the general public: https://www.ebmud.com/wastewater/collection-treatment/wastewater-treatment-plant-tours https://www.ebmud.com/wastewater/collection-treatment/wastew... Wouldn't be surprised if others do as well, or would be willing to if you asked the right person nicely.