This image is of the interior of the hypochlorite plant on Sebago Lake and shows the double tanks in which hypochlorite was mixed and the small boxes through which it passed into the water pouring into the outlet main beneath the floor in the foreground.

When the Portland Water District took over the Portland Water Company in 1908, the trustees saw the need to protect the public water supply and began to take measures to ensure the quality of the water.

The Sebago Village Brook contained a good deal of stagnant water and received drainage from both the residential part of the village and the Sebago Lake Station in use by the Maine Railroad. The Sebago Village Brook was a tributary of Sebago Lake; it fed into the lake then into the public water supply. Because of these factors, the trustees built a hypochlorite plant at the settling basin of the brook.