Keeping A Basement Dry

Friends -One of our newly acquired MHPs comes with a site-built house.  Gads, I’ve never owned a home made of bricks, and they seem to be a bit of a pain.  ;))We’ve just discovered the basement is full of 5’ of water.  Does anyone have any idea how to prevent this problem from occuring again?  We are pumping it in the next few days and don’t know if we’ll find a blocked drain down there.  But if not, then I presume we’d want to install one?  Or install a pump with a floater/trigger?  And what is best solution to seal leaking cracks in concrete?  What would you do?Thank you all,-jl-

Sounds like you’ve never lived somewhere with a basement below the water table (They’re all over the place in New Jersey)…

There are times (when it’s raining) when I look upon the mobile home park tenants with no gutters and no basement to worry about and feel a pang of jealousy.The basement is dry and always has been except for one day when the sump pump float got messed up, but I still worry. (New sump pump, new battery back up secondary pump. Big long gutters carrying water well away from the house. Need to work on grade some more.) 

You can not stop the water from coming in if you are below the water table what you need to do is control it with, as suggested, a sump pump.If you are below the water table there may be times in the year when you will not be able to stay ahead of it and you will always have the concern of a pump failure. The basement may not be usable.For now pump it out and see if there is a sump hole and determine how fast the water is coming in. Set up a sump  pump large enough to do the job and then wait about a year to see if the pump stays ahead of the water in all seasons. The best way to seal cracks is epoxy injection but you will need to install proper weeping tiles around the foundation to stop the water coming in the walls before you repair the cracks.  

You may have a water table problem.  It is very common to have water infiltration into a basement from the water table, depending on the basement wall material and condition of the water infiltration treatment that was done on the outside of the wall.  The water table will go up and down during the year and so the rate of infiltration will vary during the year.  Nevertheless, the first thing to do is get the basement pumped out and dry including any muck left behind on the floor. A dehumidifier which can be rented will help a lot.  After that, a local plumber will be able to give you the in-and-outs of the local conditions.
If the water is sewage, then you have a different problem.  Usually, the house sewer pipes will leave the building through the basement.  If the lateral to the street or the septic tank is plugged then overflow may occur in the basement drains. 
Most basement walls are made of CMUs on poured in place footings.  Some will use field stone on poured footings.  There is supposed to be a foundation drain running around the periphery of the walls at or below the level of the footings to carry water away from the walls.  This relieves the hydraulic pressure on the wall to stop the infiltration.  The drain may be plugged with sediment, missing, or overloaded due to high water table.  The hydraulic pressure is figured at 2.31 feet of water column (head)equals 1 pound per square foot (PSI).  So, at the bottom of the wall or under the basement floor you could have 2 to 3 PSI of water pressure.
A good operating sump pump is required to keep the water out.  It should be tested monthly and before the rainy season.
Jim Allen