The Emisor Oriente Tunnel, also known as the Túnel Emisor Oriente, Eastern Discharge Tunnel, Eastern Wastewater Tunnel, and East Issuing Tunnel, is a wastewater treatment tunnel in Mexico City, Mexico. At , it is the eighth longest tunnel in the world. It was constructed between 2008 and 2019 using a tunnel boring machine. Serving a population of 20 million, it runs from Mexico City to the Atotonilco Wastewater Treatment Plant in Hidalgo state. It runs at a maximum depth of 200 meters (656 Feet) below ground level and has a discharge capacity of 150 m<sup>3</sup>/s. This tunnel will help prevent flooding and serves as an alternate exit for the Emisor Central, another drainage tunnel.
In order to prevent collapse, the tunnel is constructed using a lining with segmental rings made of concrete and steel.
The estimated cost for the tunnel was 15 billion pesos (equivalent to $ million in 2008). After completion, the tunnel was realized to have gone over budget and cost 30 billion pesos (equivalent to $ billion in 2019).