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benezet 03-25-2010 02:36 PM

Sump pump running often for first time ever
I posted this message as a response to jgra's sump pump questions but realized I should ask it as my own question.

I am having a similar issue to jgra. I live just north of Philadelphia and although our sump pump has maybe gone off some (hardly ever) in the 10 years we've lived in our house, it is now going off quite often for the first time ever (once every 15 minutes)! We had three feet of snow that melted slowly (saturating the ground) and then a 3 inches of rain ten days ago, and then an inch of rain earlier this week.

During the storm a week and a half ago, our power went out for 3-5 hours and the pump didn't overflow. But the pump is still going off ten days later! Two days ago I tested the pump by unplugging it for 6.5 hours. It went from about 8 inches to 17.5 inches (our pit is 21 inches deep). But in the last four hours it only went up 1 inch and in the last two hours only a quarter of an inch.

Also, friends whose pumps go off often during storms have told me that theirs have stopped since that heavy rain ten days ago.

Does that suggest that the water table has just risen significantly?

I am very worried as I didn't think we ever had to worry about water in our basement as we thought our pump never went off (now we realize it probably did sometimes).


Scuba_Dave 03-25-2010 03:17 PM

Water table can rise for several days after a rain storm
Takes a while for all the water to soak thru the ground
I have my sump set to go on when it is about 2" below the top of the pit
That way it doesn't run all the time trying to pump ground water that will not recede for several days

just a guy 03-25-2010 04:04 PM

I'm a plumber in philadelphia and I can say that the water tables are very high right now. I would keep an eye on it for a few more days to confirm that you don't have another problem such as a leaking underground water line. But for now i wouldn't worry too much

benezet 03-25-2010 06:24 PM

Thanks for the info!
Scuba Dave and just a guy--

Thank you so much! I've been very worried (kind of freaking out a bit) as our pump hardly, if ever, went off before this.

just a guy--how would I check that for an underground leaking water line? And also, the pump has been going off less as time has gone on but it is still going ten days after that heavy rain. How long should I give it before really worrying about it? Does the fact that the water never reached the top of the pit when I turned the pump off for 6.5 hours mean that it is probably a water table issue rather than a new underground spring in my yard?

My plumber doesn't seem concerned. The old pump--which had been there at least 23 years--had its switch break a day after those heavy rains. It was still pumping but took forever to turn off. When the new pump--a Zoeller--was pumping so often I called my plumber and he said water conditions around a house can change and that as long as the pump is pumping, things are good. But as this is new for us, I am worried.

benezet 03-25-2010 06:28 PM

Question for just a guy
just a guy--I forgot to ask one other question. The sump pump pit is right next to the water meter, which I assume means that that is where the water comes into the house. Could this point to a broken water line? Any way to test for that?

Many, many thanks!

Scuba_Dave 03-25-2010 06:48 PM

You would hear water running in the pipe of there was a bad leak
It can take a week or longer of DRY weather before water table will go back down
More rain = water table does not recede

AllanJ 03-25-2010 10:41 PM

If you turn the pump off for a few hours and the water level rises in the pit but no part of the basement gets wet, then the natural water table is high given recent past weather conditions but not high enough to flood your basement.

Meanwhile the pump together with a perimeter drain system will attempt to establish an artificial water table under your house that is lower still. An overabundance of water in the ground may make the establishment of this lower artificial water table take a very long time.

Usually the pump should come on when the level in the pit starts to cover part of the diameter of any perimeter drain pipe emptying into the pit. But you can get away with setting the turn on level higher if that reduces pump run time provided that water does not seep up through the floor at the far corner of the basement.

The perimeter drain system stops accomplishing anything when it fills up with water because the level in the pit has gotten very high and the pump hasn't turned on yet.

benezet 03-26-2010 05:39 AM

No perimeter drain, I think
Allan J-- Thank you!

However, my house is old--built 1942--and I don't think it has a perimeter drain. We do not have a French drain in the basement. As I am far from an expert on this, I assume the water is just coming in from the ground into the sump pump, but I could be wrong.

I wasn't able to let leave the sump pump off for longer than than 6.5 hours (had to go pick up my daughter) but my thought had been that as it seemed that the pit wasn't going to overflow, the natural water table at my house had just risen significantly.

I am not sure if I can raise up my pump--the way my plumber installed it with the PVC pipe it doesn't seem to be "adjustable" as the PVC pipe is a certain length and is then attached to the pump.

AllanJ 03-26-2010 07:14 AM

With the sump pump by itself (no perimeter drain system aka French drain), the pump lowers the water table only for a few feet all around it unless the soil (sand?) under your house is unusually porous.

With the perimeter drain system able to empty into a sump pump pit or down the hill somewhere away from the house (i.e. is full of air most of the time) the water table will be artificially lowered a few feet on each side all along the drain system. The artificial water table can be as low as the water surface level inside the drain pipe and it gradually slopes up to the natural water table (if that is higher) as you get a few feet away.

With rare exceptions (such as having an underground spring) the water table in the space encircled by a perimeter drain system (such as directly under your house) will approximate the artificial water table established by the drain system.

benezet 03-26-2010 10:44 AM


Many thanks again.

So if I understand you correctly, if I had a perimeter drain, my pump might be going off even more as the drain itself will want to establish an even artificially lower the water table right near the house.

My soil (luckily) is not sand nor is it clay.

Without the perimeter drain, what does that suggest? If the pump only lowers the water table a few feet (vs. with perimeter drain it would try to lower the water table even more), does that mean my pump should not be going off so often? Or could it just be that the water table is so much higher than usual because of all the snow and heavy rain? The previous owner, in the disclosure when we bought the house, said the sump pump was bone dry for years and so they unplugged it. Then one winter in the 1990s the basement got wet because the pump wasn't plugged in. (I assume it was January 1996 when we got over 30 inches of snow and then a very very heavy rain two weeks later ).

I do have a French drain outside on the side of my house where the pump is, but it is several feet from the house and not that deep in the ground.

AllanJ 03-26-2010 08:55 PM

Oops, I meant to say that "few feet" refers to horizontal distance from the pump, not depth in the ground.

You only need a perimeter drain system when the level of water in the pit stays low enough that the pump remains stopped but water is still seeping up into the basement at the far side.

The way you describe things, I conclude that you just have a tremendous amount of water soaked into the ground and the natural water table has stayed unusually high for a long time.

benezet 03-27-2010 11:51 AM

Many thanks ...
Thanks to everyone who responded to my post. I really, really appreciate it.

The sump pump has significantly slowed down--to about once every 30 minutes! Unfortunately it looks like we are going to get 1-2" of rain on Sunday-Monday.

I also decided to look up Accuweather's statistics on rainfall. In the last 12 months (4/09-3/10 so far) Philadelphia has had 18 inches of above average rainfall (normal is about 41-42 inches a year). But when I chose my specific town near Philadelphia, we again have the same normal rainfall but we have had 41 inches of above average rainfall. So that means in the last 12 months my town has had DOUBLE the rainfall we normally get.

That may explain why my sump pump is going off--that much extra rain means a very high water table.

We are starting to feel that someone moved our house to Seattle without telling us ...

pkovo 03-30-2010 07:23 PM

I bet your pump is going off again! I'm in NJ, and our snow/rainfall amounts are pretty close to yours. My pit is dry most of the year, but it's been cycling at some level since that snow melted. It's gotten as frequent as every 7 minutes, and as far as every few hours, but it's not completely stopped for weeks. Right now the rain finally stopped, and it's kicking in every 20 min.

I wouldn't stress, it sounds like your pump is doing exactly what it's supposed to do. Between the rain and the snowmelt, we've just gotten a lot of precipitation. Sometimes the water table is high, or perched, and it just takes a while to drop back down. Especially if there is shale or clay in the ground (what I have)

Also, your old pump may have been set to come on at a higher water level. If the new zoeller pump is a model with a built in float the only way you can adjust that is to raise the pump up (you can set it on a few pavers) but you would probably have to adjust the plumbing.

If the new pump has a piggy back switch, then it's probably adjustable. It may be attached to the pipe. If so, you can loosen it and slide it up, so it kicks on at a higher water level.

If your pit is usually dry, I would leave it alone and let it work. They say "never say never" but how many of these storms can we get! We have to be due for a dry stretch right?

By the way, my house was built in late 40's, and had no pit when I moved in. Old timer next store (been there 40 years plus) said my house was the only one on the street never got water. Well, my luck, a bad thunderstorm dumped 4" inches in a few hours last summer, and I got a little leak. Enough to make me add a pit/pump last fall. Boy am I glad I did!

A pit without draintile can still be effective, especially if you have a good layer of gravel under the floor.

benezet 03-31-2010 04:47 AM

Thanks pkovo

Thanks so much for your info. I do think the old pump may have been may have been very quiet. Every once in a blue moon I would hear a whoosh from where the pump is and think it was a toilet flushing. Looking back, that doesn't make sense as there are no toilets that drain to that area.

I also do think the old pump was set higher, although my plumber put the new pump on bricks so it is up about 2" higher than it normally would be.

The problem is I'm just not sure about the pump having water in it before as a radon system was put in when we moved in and they put this heavy duty putty all around the pit's cover so we never opened it up.

Hearing your story makes me realize maybe this is VERY unusual weather and that the water table at my house may be much much higher than usual because of all the rain. It also makes me feel much better. I was down to every 30 minutes on Saturday but with this rain I am now at every 4 minutes.

Do you think that the fact that all that snow melted slowly made the water table higher than usual? I'm thinking that that is the most significant difference about this year since we've been in the house--the amount of snow and then a nice slow melt.

Again, many thanks.

Scuba_Dave 03-31-2010 07:19 AM

I'm used to our pump going off in heavy rains
I check it once a day
When it dries up our sump pit is empty

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