Abstract: An apparatus and method are disclosed which are suitable for detecting leakage from manholes. The apparatus of the invention comprises a rim upon which an inflatable tube is mounted, a pressure gauge for measuring gas pressure, and a valve through which air or a similar gas may be introduced through the apparatus into the manhole is included. The apparatus may further include a duct which passes entirely through the assembly and which includes a chain or cable attached to the apparatus or the cap of the duct and the other end of which may be secured within the manhole itself. In the practice of the method of this invention, the apparatus is inserted into the manhole with the safety cable attached (if such is provided) and the tube portion of the apparatus is inflated to provide an airtight seal.