Abstract: A septic tank sludge level indicator including a float assembly that can be inserted downwardly into a septic tank through a permanently installed introducer tube or access pipe that has an upper end substantially flush with ground surface and provided with a removable cap for insertion and removal of the float. The float is constructed so that it will not be buoyant in a liquid material or floating scum on the upper surface of liquid material normally found in a septic tank but will be supported when the float comes into contact with collected sludge in the bottom portion of the septic tank with the upper end of the float assembly including indicia indicating the depth of sludge in the septic tank thereby providing an indication as to whether the sludge should be pumped from the tank.