# Dislodging a seasonal water goblin in the basement



## Notaplumber1 (Nov 9, 2014)

All, 

My first post here, and hope it's a worthy one.  

We  have a leak in the east wall near the NE corner of a partially finished  cinder block basement that is as systematic and orderly as it is  bizarre and inexplicable.  In short, it leaks during three months of the  year, it leaks with complete predictability and repeatability like  clockwork, it never happens any other time of the year, and it happens  both when it rains heavily outside and when water is run in the house,  and it leaks in exactly the same way from the exact same place,  regardless of these conditions.  Here are the details as best I can  arrange them.

For starters, this basement has always been  unbelievably dry.  We've had flood conditions in the  area and at worst a tiny bit of moisture visible on the edges of the  floor, and even then, not in this corner.  Fantastic drainage.  There is  no sump system to my knowledge, other than that used by the basement  bathroom.

All that dry history changed last year when our  neighbor emptied their in-ground pool for the year.  This pool is about  125+ feet NE of our house.  It has been there for decades, and never an  issue.  It is always been drained via submersible sump onto a separate  street and out into the city sewer system.  Zero water in either yard.   But lat year, within a week of its draining, I began noticing water in  the corner of the basement closest the pool.  

Here's where it gets weird.  

The  water only appeared (a) when it rained heavily and (b) when we used  large amounts of water in the house.  And it all came out at the same  area of the basement wall.

In the basement, the main drain (cast  iron) is set along the outside wall beginning on the east side, then  wrapping around the north wall and finally exiting through the western  wall at the NW corner.  Half the house (the main bathroom, kitchen sink,  dishwasher, washing machine) dumps into the front end of the main  drain, while the other half (upstairs and basement bathrooms) feed in at  the back end, right before the trap and the exit to the city system.   The downstairs bathroom uses a sump.  

In its course the main  drain is supported on a couple of buttresses/pillars that are part of  the wall.  On the eastern wall, at the base of the buttress closest the  NE corner of the house facing the pool, about three or so inches up from  the floor, water came out of all three sides, like three little springs  of water.  The walls are painted, and in most of the leaking areas it  is like there are little pinholes in the paint where the water is coming  out.  The paint is not bubbled in those places, but it is bubbled in  some other places where water is coming out.  So no real consistency  there.

It also trickled out of the wall (also about three inches  above the floor) about a foot away from the buttress, toward the NE  corner.  There the paint is bubbled and pulled away from the wall.

When  it rained heavily or when water was used in the house, you could simply  mark the time and wait five minutes for the first signs of water.  Slow  at first, just a kind of drip, then more and more into a little  stream.  The water would increase and then settle into a decent flow,  then gradually taper off.  More water amounted to stronger flow and  longer time until it gave out, usually an hour or so later.

So if  we flushed a toilet, there might be a little water.  If we took a  shower there would definitely be some water.  If we ran the dishwasher,  we saw a good bit of water.  If we did a load of laundry, lots of water.    

Each week, the problem got worse, so that any event of water  usage in the house produced more water in the basement than it had  before. 

What is strange is that while water flushed into the  front end of the drain caused the leak (as did heavy rains), water  flushed into the back end of the drain via the upstairs and downstairs  bathrooms caused no leakage whatsoever.

Then, we went out of town  for a week at Christmas.  When we returned, it was like the problem  never happened.  Never saw another drop of water in the basement after  that.  Massively heavy rains and flood warnings in the spring, loads and  loads of laundry, all of the same things as before, but completely dry,  without even a hint of moisture.

Until this September when our neighbor emptied the pool.  And now it's all back the same as before.

I  thought for a time that maybe there might be a leak in the main drain  pipe where it rested on the buttress, and perhaps there might be a  backup in the system so a bit of back pressure caused the leak, which  then trickled down through the buttress and out.

But not so.  I  jacked up the pipe off the buttress, slid a piece of paper between it  and the buttress, ran water, and nothing.  Could plainly hear water  dumping merrily through the main pipe, but no leaks in it.  Checked all  around with light and a mirror and that piece of paper, and perfectly  sound and dry.  Indeed, the entire main pipe in the basement is dry from  end to end, no water anywhere.  Yet water is still coming out of that  buttress and the wall beside it.  And always in the same few places.  

Out  of curiosity I plugged each of the pinholes in the paint with my  fingers, just to see if the water would find some other way out, but it  didn't.  So long as I kept my fingers over the pinholes, the water  stopped.

So there it is.  I'm going crazy trying even to imagine  what this could be.  I could imagine some kind of leak in the line from  the washing machine as it goes over the basement wall and down into the  main drain, and this leak might be allowing water to get down into the  cinder block, wander ten or so feet north to that buttress and then  decide to come out there.  But that would not explain all the other  lines in the house that never cross over the wall, all of which dump  into the main drain, and all of which cause that buttress to leak,  despite the fact that the main drain is not leaking anywhere.

The  only constant is the emptying of that pool.  This year, the very day it  was emptied I saw water in the basement.  Not a drop of water in nine  months (including when the pool was filled this spring/summer), and it's  been wet down there every day since, getting worse by the week, exactly  like last year.


I'm stumped.  Any advice would be most appreciated.  I'll be happy to clarify where needed.

My thanks!


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## nealtw (Nov 9, 2014)

The fact that you get water when you use water says a leak between the house and the street. The pool bing drained causing this would indicate they also have a leak. Or perhaps a leak in the main sewer line at the street. Talk to the pool people and get the pipes scoped if nothing is found go after the city to check their pipe.

After you have that figured out you do have the problem with a block wall and perimiter drain that isn't doing it's job.
The groundwater level is being raised and when it finds a week spot in the wall the blocks fill with water and it find a hole to the inside you get a leak. When you plug one hole the water will just continue to fill untill it finds another way in.

You really need to find a sewer leak if you have one and install a perimiter drain on the ouside of the wall below the level of the floor and water proof the wall from the outside.
And welcome to the site.


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## Chris (Nov 9, 2014)

Maybe you have a burrito drain around the house. (Gravel and a storm drain pipe) that is getting saturated when the pool is drained and the waterproofing on the outside is not that great? It is the only thing I can think of that could be effected by the neighbors pool draining.


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## Notaplumber1 (Nov 9, 2014)

Thank you both!

And as my username indicates, I'm pretty plumbing illiterate, so pardon the additional questions.

Nealtw, you noted a leak between the house and street.  The street is on the west side, while the leak is on the east side---how would that happen?

Also, water never comes in when water is coming into the house; only when it leaves.  I filled the washing machine and let it set for well over an hour, and dry as a bone.  As soon as I spun it out, water showed up.  

Same thing with the bath tub.  Fill it up, no leaks.  Empty it out, leaks.

Or does that not matter in this case?

Finally, how would the seasonal thing be accounted for?  In other words, it gets worse with each week, and (if this year plays out) a brief absence makes the problem disappear.

Thank you both again!


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## nealtw (Nov 9, 2014)

Yes we are talking about your sewer drain line not your incoming water pipe.
The reason for the seasonal change would be the water level in the ground (water table). In the dry season any water leaked can be absorbed into the dirt or drain away but in the fall the water table comes up and passes the level where you have holes in the foundation.
As the water table will be fairly constant in the area anything happens in one are will affect other areas.
In your first post I got the idea that you were hooked up to a city sewer system, are you sure you are not on a septic tank system in your own yard?


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## nealtw (Nov 9, 2014)

Whatever the leak is outside in the drainage system you will have to look at waterproofing the foundation from outside also.
http://www.rccwaterproofing.com/external.php


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## Notaplumber1 (Nov 10, 2014)

Again my thanks.

And yes, I am hooked to a sewage system, not a septic system.

It also occurred to me that the city does a Spring and Fall flush of the mains, and this problem, while it began before the flushing, got worse after the flushing.

The plot thickens, evidently.

Thank you also for the link.


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## nealtw (Nov 10, 2014)

Tell the city, this only happened after they flushed their lines and want them to fix their pipe. The worst that happens when they check, is that it isn't their pipe that is broken.


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## slownsteady (Nov 10, 2014)

I'm thinking the pool is a red herring. But because the pool would be drained about the same time every year, it might indicate a seasonal problem which is just coincidental to the pool. Autumn tends to be rainier than summer. Maybe the ground is just wetter.
On a side note though, water exerts a lot of pressure on the walls of the pool, and most pool guys I know would never drain a pool as it stands a chance of collapsing inward without the water to support it. Have you asked your neighbor if they have had any problems this last year on the possibility that something has changed over there? Still, it seems too far to affect the ground around your house.
You explained the lay of your house by direction (NESW) but what about the topography around your house? Where is the high side and the slope? Is it away from your house or running down towards it.
A partial clog in your main drain could cause it to drain slow and possibly be causing a backup. The leak could be somewhere above the main drain. Is there any plumbing in the room above the leaky area?
I know these are a few random thoughts, but I hope it helps you or someone else to think this through.


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## Notaplumber1 (Dec 17, 2014)

Hey, all, 

Thanks again for the advice.  Just figured to give an update.  Seems three unrelated and weird coincidences converged at the same time.  And yes, the pool does seem to be a red herring.

First seems to have been a minor blockage in the trap in the basement.  This just conveniently coincided with the pool being drained.  Cleaned that out and no leaks from any amount of water running inside.  

(slownsteady, there is no plumbing above the leak, but good question)

Second seems to be a leaky basement window well.  That was leaking into the wall when it rained

Third is a small compromise in a section of the pipe that runs from an unused outbuilding on the property.  It runs straight into the house, joins the main drain in the house, and then runs out to the sewer.  The compromise in the walls section of the pipe is fairly high up on the pipe, so most of the time water stays put and so long as the trap is clear, water from the house gets out no problem.  But with the backup in the trap, it backs up into that pipe from the yard, the level rises, and it seeps out into the wall, and comes out in roughly the same place as rainwater.  The window well is only a foot or two from the pipe coming in from the yard, which is why everything looks to be from the same source.

It's the craziest thing any of us have ever seen.  So now the window well is sorted out, the trap leak is sorted out, and everything is nice and dry, even with rain and heavy water usage in the house.

We'll be digging out that old section of pipe in the spring to ensure the third part is finally sorted out.

To be continued.

And again, my great thanks to you all.


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## nealtw (Dec 17, 2014)

Great job, most people would have stopped after finding one thing.


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