The storms and the outages arrive together. Chicago’s severe summer thunderstorms bring high winds and lightning alongside heavy rain. Those winds take down power lines. So the hour when groundwater is arriving fastest is frequently the hour with no electricity in the house. A pump without backup power is protection that switches itself off exactly when it is needed. This is not a rare scenario here, it is a normal summer.

The clay delivers water in surges. Dense glacial clay does not absorb water steadily, it saturates and then sheds. Chicago storms drop large volumes in short bursts, and the spring thaw releases an entire winter of accumulated moisture across a few days. A pump that handles ordinary rain comfortably can be overwhelmed by a thaw, which is why sizing matters and why March is when we take the most failure calls.

Winter freezes the discharge. A discharge line running above grade or terminating at a low point will freeze solid in a Chicago January. The pump then runs against a blocked pipe, cannot move water, overheats and burns out. The homeowner finds out during the next thaw, when the frozen line is also the reason the basement floods.

Combined sewers rule out the easy discharge route. Much of Chicago runs combined storm and sanitary sewers, and discharging a sump into that system is generally not permitted and would be counterproductive anyway during the storms that overwhelm it. Discharge has to be routed properly above ground and far enough from the house that the water does not simply return.

Old pumps are everywhere. A residential pump typically lasts seven to ten years. Chicago’s housing stock is old, ownership turns over, and a great many basements are protected by a pump that was installed by a previous owner and has never been tested since.