After the recent flood in my basement from the 8 day deluge of rain in
the Northeast , I'm thinking of installing a sump pump. Most people say
to dig 2 feet deep, but what if your water table is high? There is a
2" pipe in my basement floor where an old well used to be and when I
measure the water level inside ( on normal days) it is 14" below the
floor, so how do I accomodate the sump pit?
I would dig the pit and see what the normal water table is. The water in
your old well pipe may have natural pressure raising it. If the water table
is high, just try to keep the pump below the floor and above the normal
water table. If you install it in the water table it'll probably run
continuously during wet seasons
I probably should have asked this question first. Does the water in my
old well pipe represent what my water table actually is? If not, thats
great, then at least I can dig the entire 2 feet. I guess I will not
know until I start digging.
During the flood, the water in my pipe was 2 " above the basement
floor. But the most water I saw was about an inch on the floor only in
the corners. There was nothing in the middle of the floor. The water
did not recede until I saw the water in the pipe go below the floor
line. So thats why I figured it could actually be the water table, but
I could be wrong.
You need a hole about 2 feet deep, regardless of the water table, which
you can't control. You can always set the pump to cycle on and off at
whatever level you want by adjusting the float.
The bigger question is if there is a drainage system installed around
the foundation to direct water to the sump pump hole. If you just have
a hole by itself in one corner of the basement, it's typically not
going to prevent water from appearing on the floor in a corner 30 ft
away. It will however, generally prevent a major flood from filling
the basement, as the water will make its way to the sump eventually.
With a concrete slab there is all that crushed stone underneath it that
fills up with water. When you form the sump pit with concrete you can
put weep holes in it at the level of the crushed stone. My thinking is
that with a concrete slab if you have water pushing up through in one
spot (initially) the crushed stone underneath it is most likely
submerged. For a lot with a high water table (like mine) this seems
intuitive enough. Not sure if this applies to homes with surface
That's a bit misleading, though. If you have an impermeable barrier,
(usually a layer of solid rock) with water trapped below it, then
you an have a well that pierces that barrier with a water level in
the pipe that's higher than the surrounding water level.
But for most practical purposes, the water level in the pipe
can be reguarded as the water-table, yes.
A few years ago our area experienced a very unusual rain event, about a
foot of rain over a 24 hour period. The forecasters were calling it a
500-year rain event or something like that. We got a little bit of
water in a couple corners of the basement. My reaction: now I know
what it takes to get water in the basement, and it is not going to
happen very often. I decided it ain't broke and I ain't gonna fix it.
You might want to think along those lines too, before taking a
jackhammer to your basement floor. How unusual were the recent rains?
How important is to you to have zero tolerance for water in the corner?
Without predjudice to why, it's fairly well accepted that
weather patterns are changing. I wouldn't put all that much
faith in that "once every 500 years" thing. Even aside from
that, weather tends to come in clumps, so even if it *IS* once
in 500 years, it's likely to be more like four of the next seven
years, and then 2000 years before it happens again...
You didn't say so in any post, but I gather that the water in the
corners seeped in through the walls, and also some water came in
trough the pipe in the floor.
I have some experience with sumps and perforated corrugated plastic
pipe surrounding my basement outside to accept the water and channel
it to my sump, but no experience with wells or houses on slabs.
Nonetheless: It seems to me that if you dig a sump and put in a sump
pump, you're also going to have to consider this pipe. You have to
either cap it, or attach another pipe to it and run that pipe to the
sump. Or somehow handle water that backs up through the pipe.
If you have a basement sink that might someday overflow, perhaps
because the drain gets clogged or because the sewer that it feeds into
it is flooded by a rising stream, it would be nice if the sump were
near the sink and could catch the overflow. OTOH most people don't
have sink overflows, you want the washing machine on one side of the
sink, and there might well be other reasons to put the sump somewhere
If you are not willing to dig outside down to below the slab the house
sits on, look into waterproof paint for inside the basement. It has
to go where the leak is. In my case that was on the cinderblock. But
it did an amazingly good job for the 3 more years we had the house.
(An old house my mother lived in until her first husband died, which
she rented after she married my father.)
Part or most of the pump will sit underwater all the time. The motor
won't. It's 40 inches higher than the inlet. So it doesn't matter if
the bottom foot or 18 inches is always under water. You adjust the
float level to control how high the water has to be before the pump
goes on. Mine didn't go on more than once or twice for 10 months at a
time. Now it's been going on every 10 or 20 minutes for a couple
weeks. When the water table drops again (It's probably dropping a
half inch every day, 3 inches a week), it will go back to normal.
Maybe in 2 or 3 weeks.
Remove NOPSAM to email me. Please let
me know if you have posted also.
I concur with Mike below. I will add : since water seeks low spots,
you won't waste time by trying the following except for possible
water damage if it fails..mine worked. I had inadequate drain tubes
rimming my basement and ended up installing a second basket. Just
another hole for water to flow into can be a final solution.
I rented a Bosch electric jackhammer and bought a standard sump
basket 36?deep and 20? diameter.
I dug the hole 180 deg from the original ....creating two sump pump
holes. I had difficulty getting that new depth so I only dug to 20"
and cut the bottom of the basket out. ..then put a couple of inches of
river rock on the bottom, then the pump. I put check valves in each,
and y'd the 2?" pipes into one outlet. It worked when needed. It's a
long story but those pumps ran every 40 minutes 24/7 300 days a year.
With the paint and the extra hole and pump the carpet never got wet.
Even with Akona or ?? UGL Dry lok etc... water seal paint (follow the
application directions religiously).. I had damp spots on the wall
because of wicking.
If the exterior of the basement was not tuck pointed smooth like the
interior..even with asphalt and vinyl exterior coatings, water running
down the wall on the outside will wick in. Remember that...finish the
exterior blocks...no slag ...if you are doing new construction.
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