# No water draining into sump pit



## Daniel Holzman (Mar 10, 2009)

A sump is designed to collect water from underneath the slab. The pump simply pumps the collected water out, lowering the water level in the sump, which allows higher elevation water to from beneath the slab to drain into the pit.

Therefore, in order for this sump to work, you need several things to be right. First, the pit has to be deep enough so that water flows to it. Typically, a sump pit is about 16 to 20 inches below floor level. The pump sits in the bottom of the pit, and typically requires 4 - 6 inches of water in the pit for proper operation of the pump, therefore the float is set to turn off when the water level reaches about 6 inches above the floor of the pit. If your pit is not deep enough, you will not have enough gradient to draw water from beneath the slab, and the pit will be ineffective.

A good design is to have a drain line around the house, where the bottom of the drain is at least 12 inches lower than the basement floor. New houses are usually built with a drain line around the house, typically consisting of a gravel filled trench with a 4 inch diameter, perforated PVC pipe in the bottom. The pipe is usually surrounded with filter fabric to prevent the pipe from clogging. The pipes are continuous around the house, and pitch down to a low point immediately outside the sump pit. There is a 4 inch hole drilled through the concrete foundation, and a PVC pipe feeds the collected drain water into the sump. This system is sometimes referred to (incorrectly) as a French drain, (it is more properly referred to as a perimeter drain), but whatever you choose to call it, the system works because the pipes collect groundwater from around the house, feed it to the sump, and the pump pumps out to a low area, hopefully far away from the house, or to a drain line in the street.

Your house was built in the 70's, and may not have a perimeter drain. 
Even if it does, the drain may be clogged. Or I have seen it where the perimeter drain is not connected to the sump at all, so it simply collects water, which has nowhere to go. If you do not have a perimeter drain, the only way water can get to your sump is by gravity flow. If your slab is built on a thick (greater than 8 inch) layer of crushed stone, you may get adequate flow to the drain. On the other hand, if your slab is built directly on poorly draining soil, there is simply no way groundwater is going to make its way to the sump. That would explain the dry pit. As for repairs, that is a much more complex issue. Before you even begin to think about making the system work, you need to dig outside the house to determine if there is a perimeter drain, and if so is it working. Once you have determined this, you can start the process of determining what to do next.


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## CyFree (Jul 22, 2008)

Most of what Daniel said is right on the money. 
You obviously have foundation drainage issues, and since the water only started to appear a couple of years ago I'd think that the house did have a "french drain" system, which apparently, (since they had a 70's style basement still intact down there) was working fine until almost 3 years.

Truth is, these external drain tiles do tend to clog and fail overtime, even if they are correctly installed.

What Daniel didn't mention and I would like to add is that nowadays you do not need to dig out foundations (which can be a hassle and quite expensive) to fix the problem.

For over 20 years, internal perimeter drain tiles have been used with success to keep basements dry. The best internal perimeter systems are custom developed for this purpose, and are installed by jack hammering a few inches off the slab, where it meets the walls, and installing a proprietary drain tile on a bed of gravel, the closing the gap with cement.

Those systems do exactly the same thing that the external drain tiles are supposed to do: collect water and divert it, by gravity, to a sump pump system that is installed in the lowest corner of the basement.

The advantage of internal systems is that, unlike external french drains, they are fully serviceable throughout the years. Should the clog of break, they can be easily flushed and fixed. Reason the companies offering these systems will back ithem up with a Lifetime Transferable Warranty.

In addition, they can be installed in a matter of days and for about 50% less than the cost of digging out foundations and replacing conventional french drains.

I suggest you call a few basement waterproofing companies in your area and get a free inspection and quote.


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