Water Main coming into house - is just super cold and keeps the basement cold
This question is about thermal mass/intertia.  

Suppose you are doing solar panels.  The solar energy (from the panel's perspective) is exactly the same 1 hour after sunrise versus 1 hour before sunset. So why is the house so darn cold in the morning and hot in the evening?  

Because it takes time for temperature to change. Heat energy has to actually move, and that takes time.  And insulation is all about making it take more time.   

Because it takes time, a funny thing happens underground.  The deeper you are, the less the swing.   

So we just talked about the daily heat cycle, which only affects the top couple inches of earth. There is also a yearly thermal cycle - which you know all about because the ground freezes.   Also that awkward midwest time in the spring when the first inch of soil has thawed out, but below it is frozen - so everything turns to mud!   

Anyway, if you go deep enough, the water never freezes.  

How deep? In Chicago, less than 6 feet - which is why your water line is down there. Freezing destroys water mains.  It never freezes, but never gets warm either.  

Your basement is also down there. Same deal.  

The water line is not making your basement cool.  Both are cool for the same reasons.