Wednesday, January 27, 2010

Installing a Sump

Our crawlspace gets a fair amount of water during heavy rains. It seeps through the walls in some places and collects in the corner next to our new water heater. The water level could potentially damage our water heater if it rose to the lower thermostat and heating element. Standing water generates also high humidity which will, over time, contribute to rotting the floor joists. Although the crawl eventually absorbs the water back through the lower wall over a few days, I'd like to rectify the problem before a hurricane makes it a serious problem. So I decided to install a sump.

A sump is a pit dug at the lowest point in an area in which water collects, and when it fills to a certain level, an electric pump empties it out.

I dug a hole in the location where the collected water is the deepest, next to the foundation wall.

The hole is about two feet deep. I filled the bottom with river gravel to level it, while still allowing water to percolate through.

Sumps usually need a liner to prevent them from collapsing, eroding internally, and/or to keep gravel from getting into the pump. Commercial sump liners are at least $30. I made my own out of a 5-gallon plastic bucket I picked up for $2. I drilled 1/4-inch holes all around the bucket so water could enter easily.

The liner is placed in the sump hole and gravel is used to fill in the rest of the hole. This stabilizes the liner and allows water to seep into the liner as the hole fills.

I also added some rocks around the top to help keep things level at the top and prevent a gradient which could erode the clay soil.

The pump itself is a submersible type with a simple toilet-bowl-style float switch. The advertisements about "solid construction" on the box were right - the base is cast iron unlike some of the cheaper models.

A piece of 1.5" PVC pipe serves at the discharge through the house sill plate. There is a one-way check valve on the pipe to prevent water from flowing back into the sump once the pump turns off. I also drilled a 1/8" hole in the pipe below the check valve to prevent the pump from air locking because of the check valve.

I ran a circuit with a GFCI outlet to provided power to the pump. The GCFI helps prevent electrocution, which is always an elevated possibility when electricity and water are involved.

Here is the exterior pipe for the water. Had to use a hole saw on my power drill to get through. This was the most time-consuming part of the install aside from the digging. I had to drill through two joists, the sill plate, a nail, and the siding.

The discharge connects to a flexible plastic pipe that ejects well away from the house.

Tested it with a 5-gallon bucket-full of water a few times, it works great!

Update: 6/2/2012:

Its been more than a year and the sump pump still works fine. It only runs periodically now if it rains really hard for more than a few days and some water leaches in through the foundation. I end up running it more myself testing it when I drain my water tank on a yearly basis as its a convenient place to dump the water.  The drainage network I installed in our back yard has really solved the crawl space water issue.

1 comment:

Wendy Hutson said...

Hi mindtomachine ,
Thanks a lot for help me by
posting this useful post!
Installing sump pump was not clear to me before.
But by reading this post , i gained a lot of
useful common factor.
Great thanks!