Old sump pump - new water?

[Nic3456]

Sorry for long post, but wanted to set situation -
I’ve been in my house for ~5 years. Typically my sump pump runs a lot when it rains - however if it doesn’t rain it doesn’t run - especially in the summer (I could go 2-3 weeks without a cycle). Starting around the beginning of August I noticed it started running once a day and pumping out ~40-50 gallons even when we had no rain (my battery backup tracks #of pumps). About two weeks ago I noticed it started pumping the 40-50 gallons every twelve hours which is starting to have me concerned. I know the water table can shift but early fall should typically be the low point. As an experiment last week I kept manually pumping until the pit would roughly stay empty and it took about 500 gallons in total. About 16 hours later the pit refilled enough so the pump ran again with no rain. So far I turned my house water off for an hour and noticed no leakage, my house is about 500’ from the road where the water main is. I only average using 100-150 gallons of total water a day so I really don’t think that’s it. I did have a pond installed about a year ago (and has been full for 6-8 months) - it’s about 70’ away from the house on pretty flat ground slightly dropping from house. I would guess the bottom of the pond is probably about the same depth as the sump pit. I have pretty heavy clay soil. Another thing is they started building a new neighborhood about 1500’ away that was mostly flat cornfield with some trees. That land is roughly the same surface elevation as me, if not slight lower. All downspouts, sump drains,etc have been checked and appear to be fine. Could my pond be leaking from that far away or construction impacting from that far away? Or something else I haven’t considered - I’m quite perplexed…

 

[Tuttles Revenge]

I had a client who after cutting down several large conifer trees started getting water in their basement. The arborist said that those large trees soaked up 500gal a day each.

 

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[Jadnashua]

When nobody is using any water, look at your water meter...you may have a water leak. If the leak is before the meter, it may not show up on the meter, but if you have the water tested, they can often tell if it's municipal water, or ground water, but not always. You might check with the utility company to check for leaks.

It could be ground water, but it might be potable water, too. Depending on where you are, a small earthquake could have opened up a path for ground water that wasn't there previously, and various things could damage your supply line underground, too.