First question: are you sure
the sump pump was cycling less frequently at some point in the past, or is possible that you just noticed the increased cycling?
If you have a leak in the supply plumbing, and the sump pump is running several times a day, that would mean it is leaking at least several cubic feet of water per day close to the foundation drain tile system.
If you have a water meter (not all homes in Chicago do), and the leak is on your side of the meter, you can use the meter readings to check for the possibility of a leak - the next time you will be out for the day make sure nothing
(including ice makers, etc.) will be consuming water, note the meters exact
reading, and see if it is increased when you return.
If the leak is on the city side of the meter (for example because of foundation settling which has damaged the water line where it passes through the foundation wall) it's a lot tougher to diagnose, ultimately you might have to turn off the water at the curb box in dry weather and wait to see if water flow into the sump is slowed.
However also consider other possible reasons for constant flow into the sump.
For example, is the pump discharge sufficiently far from the structure so that it's discharge cannot reenter the foundation:
This is a pretty dramatic example, but the principle is the same for lower flows. (This pump was in Chicago, BTW, and also illustrates that you can get substantial amounts of groundwater at the foundation drain system even in freezing weather in our Chicago climate).
How about your neighbors
sump pump discharge - for instance I sometimes find these peeking out from under the fence of adjacent properties.
Also, where are gutters and downspouts currently discharging?
It these are discharging into areas where water can return to the foundation drain system the ground can store large amounts of water which gradually seeps back into the foundation drain system - this can cause cycling of a sump pump even after weeks of "dry" weather.
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