What is a Footing Drain?
A discussion about sump pumps must first start with footing drains. A footing drain or foundation drain is a system of perforated pipes beneath a basement foundation. The footing drain pipes are designed to keep groundwater from seeping into the basement. Up until about 1980 footing drains were allowed to connect to the sanitary sewer system. Because sanitary sewers are usually deeper than basements, the sanitary sewer was useable as an outlet for footing drains.
However, the flow from footing drains can increase dramatically during rain events, and this wet weather flow from footing drains can overwhelm a sanitary sewer and cause sewage to backup into basements. For this reason, around 1980, building codes started to change. This change prohibited the connection of footing drains to sanitary sewers, and thus required the construction of a sump pump to collect the footing drain flow and discharge it to the surface or to a storm sewer.
What is a Sump Pump?
A sump pump removes water that is collected by footing drains and discharges it out of the basement and away from the structure. In homes built after about 1980 when the building codes changed, the footing drains are collected into a sump pit in the basement. A sump pump in this pit then pumps the water from the footing drains out of the basement. Typical sump pumps are rated for about 0.25 – 0.50 horsepower and are capable of pumping 20 to 30 gallons per minute. These are small, low power pumps that are designed just for pumping the flow from footing drains. Sump pumps are usually connected to 1.5-inch or 2-inch pipes that discharge either to the surface or to a nearby storm sewer.
Sump Pump Information Resources from Ann Arbor, Michigan
The City of Ann Arbor, Michigan performed an extensive footing drain disconnection (FDD) project that removed about 2,000 footing drain connections from their sanitary sewer system. The program was very successful, removing around 70-80% of the wet weather inflow and infiltration from most of the districts where it was performed. As part of the program, the City developed some excellent resources for their residents about sump pumps. These resources include a series of information PDFs and videos about sump pumps on topics ranging from how your sump pump works, to operation and maintenance tips, to backup systems, and many other useful topics. Below are links to several of the sump pump resources that the City produced.
Links to Sump Pump Videos:
- Your Sump Pump: How Does It Work?
- Sump Pump Backup Options
- Sump Pump Common Points of Failure
- How to Keep Your Basement Dry
- Sump Pump Glossary
- Your Basement: Where Does the Water Go?
- Annual Sump Pump Maintenance
- Water Powered Backup Maintenance
- Whole House Check Valve Maintenance
Links to Useful Guides and Checklists (PDFs):
- Sump pump backup options
- Sump pump maintenance checklist
- Sump pump and collection system glossary
- Sump pump installation inspection process
- SPIM program typical modifications
- Home exterior sump pump curb drain
- Air gap types
- Keeping your basement dry
- Water powered backup maintenance
- Sump pump common causes of failure
- Whole-House Check Valve Maintenance
- How to Quiet a Noisy Sump Pump
H2Ometrics Tools for Footing Drain Disconnection Programs
H2Ometrics has been used extensively to evaluate the effectiveness of footing drain disconnection programs and quantify the flow removal from these programs. The H2Ometrics platform contains many tools that are useful for evaluating flow data from sump pumps and footing drain disconnection programs. These include visualization and plotting tools to view the data collected by flow meters and rain gauges, metrics tools to perform analysis on flow meter and rain gauge data, meter correlations and other modeling tools to evaluate the flow removal from a footing drain program, and many other useful tools.
This is very informative article to know more about sump pumps. Sump pump become important for basement to protect it from flooding.
MY sump pump runs every 15 minutes, even when not raining. if I unplug the pump, the pit fills fairly quickly to about half way full then stops. I believe that if I raise the pump elevation in the pit, (with bricks, etc.) to get it above the water table, the pump will run only when needed. Do you see anything wrong with this idea?
It sounds like your sump elevation might just happen to be right in the middle of the ground water table, and your pump may be the lowest relief point for the area. If that is the case, you might be dewatering the groundwater table for the whole area. Raising the pump elevation might help, but the groundwater might also just rise a little, if it does not have another outlet, and continue to reach your sump pump. In raising the elevation, you would also decrease the storage capacity before the ground water might reach your basement level, which could have an adverse impact during large storms or a sump pump failure. So there are trade offs to everything.
It might be worthwhile to experiment with your idea and see if it helps, while also being aware of the potential negative consequences that I mentioned. You might also consider dual sump pumps to share the load or having a spare pump on the shelf and the tools ready to go for quick replacement if the pump fails do to its frequent operation. Good luck!
Do footing drains let basement flood goes out (unplugged sump pump) after heavy rain? Just wondering why they are designed not to. Thanks.