# How to determine the lowest point in basement?



## sumpchump (Mar 15, 2010)

Whats the best way to determine where the lowest point in your basement is?  Can someone give me some tips?  Im looking to install a sump pump.

Thanks,
SumpChump


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## oldognewtrick (Mar 15, 2010)

sumpchump, welcome to House Repair Talk, if you don't have carpet on the floor just drop a marble or ball and watch where it rolls. It will usually find the lowest point.


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## sumpchump (Mar 15, 2010)

oldog/newtrick said:


> sumpchump, welcome to House Repair Talk, if you don't have carpet on the floor just drop a marble or ball and watch where it rolls. It will usually find the lowest point.



Thanks for the advice, however the basement is not just one square room.  It has multiple rooms and walls.  Floor is concrete and not finished.  

Thanks,
SC


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## inspectorD (Mar 15, 2010)

You want to find where the water goes...get some water on the floor.
Use a five gallon bucket of water poured onto areas of the floor to find the low spot...then a shopvac to clean it up soon as possible.


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## Wuzzat? (Mar 15, 2010)

sumpchump said:


> Thanks for the advice, however the basement is not just one square room.  It has multiple rooms and walls.  Floor is concrete and not finished.
> 
> Thanks,
> SC


What's your plan if there are several low points?

You may want weep holes in the walls at the bottom to equalize the water level.

5 gals will give you a depth of 1/16" in an 11'x11' room.

And a marble will work if you first put down a large sheet of tempered Masonite or glass or Plexiglass.  You are kinda' looking for an average slope.  One site recommended a slope of 1 in 100, like a rain gutter, but that seems steep.

"
SUMP PUMP INSTALLATION: 
Installation of a pump and its location will depend on the type of water problems you have and what the local plumbing and electrical codes require. If you install a pump only as a safeguard against an unexpected flooding situation, and have only a slight amount of water tinder normal conditions, locate the sump pump in the lowest part of the basement near an outside wall. Locating the sump in a low spot will assure that water will run to the sump.
. . .
If the water problem is really serious, you may need to cut out small channels in the floor to funnel the water into the sump. These channels should be more like depressions rather than trenches. Make them approximately 2" wide by about 1 " deep. Draw the position of the channels on the floor at the same time you lay out the floor for the sump system.
"


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## oldognewtrick (Mar 15, 2010)

sumpchump said:


> Thanks for the advice, however the basement is not just one square room.  It has multiple rooms and walls.  Floor is concrete and not finished.
> 
> Thanks,
> SC



Well then get a water level, basically clear tubes that screw on to the ends of a garden house. Fill the house up with water untill the level reaches a level in both tubes. And you can test how ever long the hose is.


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## inspectorD (Mar 15, 2010)

oldog/newtrick said:


> Fill the house up with water untill the level reaches a level in both tubes. And you can test how ever long the hose is.



Me thinks you mean fill the hose up with water...not the house....couse he would find where he needs the sump pump starting with the fire department.


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## Nestor_Kelebay (Mar 15, 2010)

I think the marble idea is probably as accurate as you need.  If there are partition walls in the basement, and the marble comes to rest against a partition wall, simply move it to the other side of the wall and let it go again.

If you do that from several points in your basement, and it ends up at the same place each time, that's your lowest point.

However, I expect Wuzzat? is probably right.  There are probably several dips in your floor, and puddles will form in all of them in the event of a flooded basement.  Still, a shallow puddle can be removed with mop and pail.


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## sumpchump (Mar 16, 2010)

My basement is currently under 3" of water as we just received 7-8" of rain in 3 days.

Time for a sump pump!

I dont see how a marble will tell me the lowest point in my basement since our basement is approx 1000 sq. feet.  Im sure the concrete floor is not perfect and will have some dips so the marble may roll in many different directions depending on what side of the floor I place it on.  Same issue with the bucket of water idea.  All these sites tell you to install the pump at the lowest point in your basement, but none tell you how to find it!

And before anyone asks we are getting water up through the cracks in the floor.  Seems to happen every 4-5 years when we get 6-8" of rain in 2-3 days.  My backyard is approx 6' below my neighbors house and all that ground water saturates my yard and then my basement.  Joy...joy...

Has anyone ever used a 12 or 16ft 2x4 with a level on it?  Would this work (assuming I can find a 12-16 ft 2x4 that is straight)

SC


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## oldognewtrick (Mar 16, 2010)

sumpchump said:


> My basement is currently under 3" of water as we just received 7-8" of rain in 3 days.
> 
> Has anyone ever used a 12 or 16ft 2x4 with a level on it?  Would this work (assuming I can find a 12-16 ft 2x4 that is straight)
> 
> SC



Well, I guess when you start draining the water the last bit left on the floor will tell you where the low spot is.

Instead of a 2X, with the aid of a helper, stretch a string and a level that hangs on the string, you can get them at most hardware stores. You wont have to try and find a straight 2X.

...I really didn't mean fill the _house_ with water


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## Wuzzat? (Mar 16, 2010)

oldog/newtrick said:


> Well, I guess when you start draining the water the last bit left on the floor will tell you where the low spot is.



Yes.  The water is already there.  When it gets down to 1/2" some high spots should be showing.


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## handyguys (Mar 16, 2010)

water level as mentioned. I would use a laser level. I have a cheap black & decker one but I think its discontinued. There are a bunch of self leveling one out there that are cheap enough and very handy. They draw a level horizontal laser line.

When you have the line you can just move a yard stick or something around and measure down from the line in various spots. Make a mark on a door jamb where the line is and then move it to the next room and continue.
With this method you can find the lowest spot within the accuracy of your measuring tools. 

Oh, but you really only need to be close. Sometimes convenience of installation comes into play as well. Also, if your water issue is below slab ground water then your lowest spot is the bottom of the sump bit. If its surface water you should address your grading, gutters downspouts, etc.


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