Monday, April 7, 2014

The external sump pump could be the solution to your wet basement

The external sump pump.

Every new home built today is built with a sump pump, it is installed in the basement or crawlspace of the home. It is installed in a sump pit, this basically is an oversized plastic pail that is located below the concrete floor of the home.

There is another kind of sump pump, it is called an external sump pump. It is installed on the outside of your home. It is installed in what is called a sump well, the sump well is located 5 to 10 feet from the outside of the home.

The well usually is made from concrete, one of the most commonly used things to form a sump well are concrete well tiles. They are roughly 3 ft wide in diameter and about to 2.5 feet high, they are manufactured in a circle and they are designed to fit on top of one another. They are excellent at holding back the ground creating a perfect place to have access to an underground pump.

You install enough concrete pieces so that there is an unobstructed well that is deep enough that it is below the house sump pump, this should put the external pump below the footings as well.

Once you have the well tiles installed, you redirect the house weepers so that they run into the external sump well instead of first going into the sump pit inside. This will cause the sump well to fill with water. You then install a sump pump at the bottom of the sump well and pipe it up and out of the sump well away from the house.

The reason that you would do this instead of relying on just the interior sump pump is because the water volume around the house is so great that the internal sump pump can’t keep up and the foundation of the house is being saturated with water. Instead of allowing the water from the outside around the house into the internal sump pump, you move the water into the sump well outside. This allows the internal sump pump to only deal with the water that is directly underneath the house.

The sump well also has the ability to hold a fair bit more water then the internal sump pit. This is a safety system so that if and when the water is overwhelming for the pump at the bottom of the well it doesn’t overflow out of the well. It contains the water inside until the pump is able to move it.

External sump wells are usually installed as a retro fit to help finished homes that have high water volume problems ease the pressure around the foundation.

Rob Abbott
Operations Manager
Village Builders Inc.

38 comments:

  1. Sump Pumps generally range from 1/3 to 3/4 h.p. and are rated by their maximum pumping ability in GPH (gallons per hour). A sump pump with battery backup can run continuously for 6 to 12 hours before the battery looses it's charge. This is enough to bridge most power outages. If your electricity is out longer than that, a generator could keep it going indefinitely but you'll have to make sure the sump pump is on a circuit served by the generator.Details here

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  2. Hi Rob. Love all the information from the blog. Very informative. Question in regards to external sump pump. We are building in area that has high water table. The builder has advised that we should install an external sump with a French drain before he starts on the footings and then the weeping tile would be installed after that. This is what he had to do with another home in the area after lengthy delays because of the groundwater and rain this spring. It seems a little redundant to me. I can see how it would help them dry out the area to do footings etc but not sure long term if that's something that's required. The French drain/external sump is apparently my cost and a significant one at that. Any insight would be appreciated. Jeremy. coldstream76@gmail.com

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  3. hi rob, any special needs for winter on SW ontario?

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    1. In what way do you mean special needs?

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    3. Like could the cold winter weather freeze and damage the pump?

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    4. If you were worried about that you could insulate the lip and top section of the concrete well tiles. The actual pump sits at the bottom which would be (depending how deep your basement is) 8 to 10 feet which is well below the frost line where the ground is still warm, also the water down there is warm also. In SW Ontario it wouldn't ever get cold enough for long enough to freeze anything.

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  4. Hello, I have calculated that my sump pump moves over a million gallons per year. I want to retro in an exterior sump pit. However, I'm not sure how to tie it into the existing interior sump pit/ existing perforated drain tile? Any help/ diagram would be appreciated!

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    1. The external sump pump when placed on the outside ties into the weeper system that is already placed around your home at the footing level. This is the tile drain that is already connected to your internal sump-pump. You tie into that line with a T joint and run the line into your new external sump hole. As long as your external sump hole is deeper then the interior one then the bulk of the water will run to the external one by gravity and hydrostatic pressure.

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  5. Hi.. there is a high water table against the front of my home and as best can be determined there is no footer drain along the foundation. Back yard is not proble due to being on a hill. So to relieve pressure I was thinking an exterior sump pump located outside the foundation on the front side of the house. This would stop leaking through the front foundation wall (i think).. Does this sound reasonable? Who should I call to investigate ? Thanks Steve

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    1. Hey Steve, yes the external sump pump will lower the water pressure on the outside of the house, but if you are going to all the trouble to dig a big hole and install well tiles and a pump then you might as well dig the rest of the front out and install weeping tiles so that something feeds the pump with water.

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  6. can an external sump pump be useful in ground that freezes. The winter snow melt needs to be moved away from the house. There is no sump pump in the house.

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    1. Yes, remember that the ground only usually freezes 3 to 4 feet down, below that the ground accepts the melt water. Around the external sump pump well the water would collect in the pit and sump pump would remove it from the area.

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  7. Hello Rob, I appreciate all of the insight you have provided on this blog. I have a high water table, two sump pumps in opposing corners of my basement. I'm getting water seeping in at the footing on one wall of my house. I have interior drain tiles all the way around the basement, and exterior footing tiles as well. The leaking side of the house was dug up all the way down to the exterior drain tile. Upon inspection that tile had water in it and was flowing freely. We repaired a crack, re-tarred the wall added 3 feet of gravel along the entire length of the house on that side, and then installed Delta board and the accompanying flashing as well. Unfortunately I have seen no change in the amount of water coming in at the footing. i am thinking it is a hydrostatic pressure issue, and wondering of you think an exterior sump pump would alleviate this pressure enough to resolve my issue. I'm sure you may have additional questions but, I would greatly appreciate any feedback or insight which you may have on my situation. Thanks

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    1. An exterior sump pump would help, it would pull water away from the house. But you would have to dig down past the house and install well tile below the level of the foundation. What would then happen is the water would endlessly fill the well tiles and the sump or pumps depending on the amount of water would remove them out of the area. You would have to have the tile drain from around the house go into this. That said this doesn't mean that it would guarantee fixing the hydrostatic pressure issue you have in your basement. The biggest problem you have is that your house is built to low in the ground. There isn't much you can do about that, unless you wanted to abandon your basement and fill it with gravel and top it with concrete (I've seen someone have to do this). That's an extreme case. If you have any kind of hill or grade towards ditches and you can get a gravity drain installed that would releave all your water pressure problems naturally. Your options are limited.

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    2. Rob, Thanks so much for your response. Can you briefly describe the way a gravity drain works, and possibly recommend a resource where I can learn more about them? Thanks again Rob

      Andy

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    3. Andy, gravity drain is basically you greating a relief point for the water to naturally run away from your house. To do this the water needs somewhere to go. You have to install a weeping tile from the corner of your house and then dig a trench to a lower spot away from your house like a ditch. You then put the weeper in the trench, fill with gravel and cover with dirt. If you can get all the way down to your existing weepers (tile drain) and have negative drainage away from the house then the water will naturally follow gravity away from your house without the use of pumps.

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  8. It was really insightful.
    Thanks for such a nice content.
    Cheers
    BTW if anyone interested more have a look batterymodeon.com thanks

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  9. Hello
    I have an internal French drain and 2 sump pumps, and spring time thaw and rain sill will flood my basement. I have been reading about the external sumps and I am wondering why you could not put in a shallow well instead. Any advise / thoughts ???
    thank you

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    1. A shallow well is basically the same thing, except that a well has certain extra things that have to be done to it to make it safe for human consumption. An external sump pump is installed inside well tiles to eject water away from the building only.

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  10. Hi Rob,

    I am in Calgary and I have never seen water in my WALKOUT basement in last 20 years (even during 2013 flooding). There is however ground water in my area and I found water 1.5 feet below concrete foundation last year during landscaping the backyard (it is 1.5 feet below the floor level). I have 2 questions (a) Do I need sump pump to drain this water to protect foundation? (b) If yes, then what is best outdoor pump available that will be good for -40 deg C. Will it work after it has seen few winters? (c) what is the best way to protect pipes from freezing (d) Any recommendation for contractor for outdoor sump pump installation in calgary area?

    thanks

    Josh

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  11. Sorry more clarification for point (c) above : by pipes, I mean pipe at the discharge of the pump

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    1. Since you have a walkout basement you are above grade at the backend. As long as the drainage around the house is a negative slope away from the building then you will limited on the amount of water issues you have. You said you have a high ground water table, as long as it doesnt turn into flooding you should be fine, the concrete frost walls below the walkout will be fine sitting in ground water it will not damage them. Unless your worried about surface water coming in the walkout then I wouldn't worry about installing sump pumps. There should be an interior sump pump in the home if its newer. THe other thing you could do is find the weepers that wrap around the foundation (they will not be that deep in the ground on the walkout side) and attach a t onto them and run a length of weeper away from the home to the downward slope if that's possible.

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  12. Great information. Thanks for sharing sump pump guide. Also you can learn more Sump pump check valve

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  13. Hey Rob,
    Recently installed a French drain that is gravity fed into a drywall. The foundation is 4ft down and the drywall is 6ft with the bottom being a clay layer. The drywell is full and has begun to back up into the weeping tile. The frost line is around 7m and was thinking a exterior sump pump would have to be installed in the pit. Any thoughts?
    Cheers,
    Shawn

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    1. If your dry well is full and your still worried about the amount of water around the house then yes you should install a pump in the drywell. Set it so that it is below the foundation, you dont need to set it at the bottom of the drywell. You just need to move the water away from the house foundation.

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  14. We recently had a sump pump with battery backup pump installed right outside my walk-out basement in the ground about 6' deep in a plastic well container. They left the battery in a plastic case with the controller on top of the sump pumps container. I called the manufacture and they said it was not meant for outside use but I could in-case the battery with some insulation in a box. How long will the battery last if I decide to do this? Should I get rid of the battery back-up and ask them to install just one sump pump? Help

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    1. Battery back-ups are made to back up a normal electric sump pump when either the power goes out or the primary pump fails. It is a short term in an emergency option. If you have enough ground water problems to need an exterior sump pump then you really should have a normal sump pump that is connected to permanent power. You don't have to get rid of the battery backup, just have it remounted above the new primary pump.

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  15. hi Rob, I live in Montreal Quebec. Is there someone in the area you could suggest to install an exterior pump?

    David

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  16. Rob I am wanting to install a catch basin and sump pump where I have a low spot in my yard. I have researched pumps and reached out to several companies. What pump can stay outside and one that can be rewired as it will be about 100 feet from the pump to the circuit breaker? Thanks so much

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  17. The distance from the house to the pump isn't a big factor for the wiring, for the pump you should rely on a plumber to supply and install the pump. If you place the pump in a covered well in the ground then the pump will be fine.

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  18. Hi Rob, we just had an exterior sump pump installed and would like to cap off one of the pumps in the house(we have 2). Should we wait and see if it slows down first or just cap it off hoping to force the water to redirect itself to the outside pump.

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  19. The one we want to cap off is just for water under the slab. We will leave the one that is attached to the weeping tile.

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    1. I would wait if I was you. The reason that you installed an external sump pump is to help control the water, I wouldn't start limiting the amount of water that you can move until you know that the external sump pump can handle the load required.

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  20. Hello Rob
    Thank you for enlightening this British girl about Canadian sump pumps. I have water seeping into my basement and contacted the city council and a plumber. The city said an external sump was fitted when the house was built in 1983. There is no sign of the sump outside the house. The plumber said it has probably been landscaped over and to start digging. I know it is on the west side of the house but the area to dig in is quite large and it could be 2 or 3 feet deep.
    Would a metal detector help?
    Can you help me narrow down the search as I do not want to dig up my front yard.
    Thank you. Warm wishes Helen

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    1. Hi Helen:

      I'm in a very similar situation to you.

      I moved to Canada a bit ago and tried to figure out all sorts of sump pump issues around what used to be installed in my house.


      I went the metal detector route, but couldn't find anything. You could try, but should hire someone familiar with metal detectors, if you aren't.

      In the end, I had to dig a 4-foot deep trench in the area where it was the most likely placed. I found the pipe and was able to track it in both directions.

      I hired a crew with equipment that could dig it quickly.

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