Sump Pump has got me Stumped
Was a drone spotted over your house any time recently? 
It sounds like a bunch of water had accumulated below the grade of your basement floor. Is it possible some had overflowed and found its way to the lower spot your noticed the accumulation? Then the area between the pump liner and the accumulated water dried up naturally just leaving the puddle. Do you keep a dehumidifier running down there?
Water finds its own level so maybe there was a lot accumulated in the ground around your house, just below the grade of your basement floor. If there was more rain it might have eventually overflowed more into the basement. Do you know if there’s a layer of gravel under the floor? Could be a lot of water was sitting in that space.
How old is the pump itself? The float seems to be sticky.
Where do the inlet pipes come from?
Water in our area has substantial mineral deposit. We experienced the results of this in Millburn when sump pumps had to be replaced and piping to the furnace became clogged with iron deposit.
There may be a connection to what you are experiencing.
The underwater streams in your neighborhood have been known to overflow sending water up through the basement floor. This is a possible cause of water ponding on your basement floor in an area away from the sump pump.
joan_crystal said:
The underwater streams in your neighborhood have been known to overflow sending water up through the basement floor. This is a possible cause of water ponding on your basement floor in an area away from the sump pump.
Is there a map of where the underground streams flow?
Formerlyjerseyjack said:
Is there a map of where the underground streams flow?
I think it’s kind of a map of Maplewood and South Orange 
It seems that water is coming up through the concrete slab. Not exactly coming in through the exterior basement walls, where the drain lines are embedded close to the wall. Some of it flows into the drain around the perimeter of the basement walls but if the float switch in the pump is stuck then it backs up into the drain pipes.
It sounds like the pump is working just fine, it’s the float that needs to be jiggled around every so often. Is the float the ones that are in a ball on the end of a rubber tube? Those are likely to get stuck due to inactivity. I changed my pump to one that has the float going straight up and down a metal rod. This way the float stays in place and not likely to be snagged on the wall of the sump tank.
meta photo of the pump I now have.
joan_crystal said:
The underwater streams in your neighborhood have been known to overflow sending water up through the basement floor. This is a possible cause of water ponding on your basement floor in an area away from the sump pump.
What I'm having trouble understanding is why the water did not overflow above the sump pump liner. A surge of water rushed into the liner through both inlet pipes (see graphic) discharging continuously after about 30 seconds repeatedly for about 20 minutes after I got the pump to start working again and the water level dropped below the openings of the inlet pipes. Then the flow continued at a slower pace and it's still trickling in 14 hours later.
Why did the water stop flowing into the sump pump liner (basin) but instead start seeping into the basement through the base of the walls?
Does it have something to do with water "seeking its own level"?
I'm still stumped.
Jaytee said:
It seems that water is coming up through the concrete slab. Not exactly coming in through the exterior basement walls, where the drain lines are embedded close to the wall. Some of it flows into the drain around the perimeter of the basement walls but if the float switch in the pump is stuck then it backs up into the drain pipes.
It sounds like the pump is working just fine, it’s the float that needs to be jiggled around every so often. Is the float the ones that are in a ball on the end of a rubber tube? Those are likely to get stuck due to inactivity. I changed my pump to one that has the float going straight up and down a metal rod. This way the float stays in place and not likely to be snagged on the wall of the sump tank.
meta photo of the pump I now have.
"if the float switch in the pump is stuck then it backs up into the drain pipes"
This sounds like what happened. But what is causing the water to "back up"? When the inlet pipes were exposed, the water came out with force, like when you open your faucets in the bath all the way. Hard to imagine that "backing up," but maybe there's an explanation.
My sump pump looks like this:
We have an addition in the rear of the house that has a full basement with a sump pump that has worked flawlessly over the last 30 years, with one exception when the original pump failed and had to be replaced, about 10 years ago.
Last night during a light rain following the day's rain, I noticed about an inch of water in the side of the basement opposite the sump pump (the floor was not properly graded and water doesn't flow toward the sump pump). I think it had rained most of the day, but it didn't seem like enough to cause a small flood, so I assumed I had a clogged gutter.
I proceeded to vacuum up the water and went to bed, assuming the problem was over since the rain had stopped.
However, the next morning, I went to check out the basement and was surprised to see about the same amount of water that I had vacuumed up in the same area of the basement as the night before. The area near the sump pump was still dry.
I vacuumed up the new water and started looking for where the water was getting into the basement. Up to this point I hadn't looked at the sump pump since there was no water on the floor in its vicinity. In my search for the source of water I reached the sump pump and saw that the liner was filled to the top, over the sump pump, but not high enough to flow onto the basement floor. The water looked very still as though it hadn't been agitated for a long time. It was not clear, but cloudy and brownish.
I jiggled the float up and down until the pump started working and soon it started to discharge water. When the water level of the liner fell below the openings of the inlet pipes, water started gushing into the liner, faster than I can recall seeing before. As the water level rose, the floats started to work and the pump responded normally and discharged the new water. This went on ferociously for a bout a half hour, and then the pace slowed down to a kind of normal discharge rate and continued for several hours. The water on the floor on the far side of the basement was beginning to evaporate.
What I don't get, is why didn't the water overflow out of the sump pump liner since the pump was not working and as indicated above, there was plenty of water trying to get into the liner through the inlet pipes?
Six hours later, the pump is working normally.
Is the problem fixed or should I expect a repeat performance?
Any insights and recommendations would be greatly appreciated.