Simplified apparatus is provided for injecting controlled amounts of a chemical housed within a container into a liquid, such as water, flowing through a pipe. A ''''T'''' fitting is coupled into the pipe through which the liquid is flowing by means of a second T fitting or in any other convenient manner. A length of tubing coupling the output from a container holding the chemical to be injected extends coaxially through the T and into the pipe through which the liquid is flowing, terminating just short of the opposite side thereof. A second length of tubing is coupled between the right angle extension from the T to the inlet of the container. The area at the outlet of the tubing extending through the T is smaller than the area surrounding the tubing through which the liquid in the pipe may pass to communicate with the second piece of tubing which leads to the container inlet. Thus, in effect, a suction is observed at the outlet terminal which draws liquid flowing through the pipe into the container, where it mixes with the chemical therein, and back into the pipe conveying the liquid. Flow rate through the container, and hence the concentration of chemical injected into the liquid flowing through the pipe, is controlled by a conventional valve on the inlet side to the container. Additionally, a second conventional valve may be added to the inlet side to the container and a third conventional valve to the outlet side of the container to permit complete isolation of the container to facilitate replenishing the chemical contained therein. If necessary to conform to building codes, a check valve may be inserted into the line on the inlet side of the container.