In most cases, your home’s sanitary sewer is ultimately connected to a municipal sanitary sewer system managed by your town.
Your sanitary system is usually called the sanitary service and the towns system is referred to as the sanitary main.
Many older homes (and a few newer ones) are configured where your sanitary service exits the building below the lowest level, often under the basement or lower level floor.
One of the reasons the sanitary system becomes backs-up is because some neighborhoods combine their sanitary systems with their storm water systems, so rain water collected in gutters and sump pits, is discharged into the sanitary lines.
Another source for the increase in water volume is from homes that have illegal connections where the storm water sump pit has a pump connected to the sanitary system.
During times of heavy rains, the sanitary main can become charged or filled beyond its capacity to effectively drain off because it cannot handle the increased volume of water.
Because water seeks the path of least resistance, a sanitary system filled to capacity will back up or spill out through the lowest available opening, often found to be a floor drain or other plumbing drain located in the lowest level of the connected buildings.
Most newer homes are designed to eliminate the back-up potential by running the sanitary service line through the foundation wall, above the lower level floor. They separately collect all lower level sanitary waste into a sealed basin or sanitary pit. The pit contains a pump, often referred to as an ejector pump, which pumps the sanitary waste upward and into the sanitary service line.
This is referred to as an overhead sewer system, so named because the lowest opening in the system is designed to be located above the head or high water level of the sanitary system.
To better protect a home that does not have an overhead sanitary system, there are a few options.
Backwater Valve System
One option is to install a backwater valve system on the sanitary service line. A backwater valve includes a horizontal check valve designed to allow the sanitary waste to flow in one direction only. A brass metal disc is hinged to swing open as sanitary waste flows toward the sanitary main, and closes shut when waste begins to flow backwards.
Optionally, a basin is installed before the check valve where the building waste is collected, and a pump is installed to force pump the waste up and beyond the check valve, back into the sanitary line.
The concerns with a backwater valve system are maintenance and failure.
Maintenance is required annually to keep the disc hinge and assembly bolts lubricated. The pump is located outdoors and also needs to be checked annually due to weather conditions, as does its electric supply and connections.
Failures are often caused by debris in the sanitary line. A tight wad of paper material is all that’s needed to prevent the disc from completely closing – rendering the whole system useless.
Adding to the issue is the fact that the system cannot be rodded through the check valve, so any rodding needs to be performed either by removing the horizontal check valve disc, or by rodding from two separate ports (one before and one after the horizontal check valve), stopping before the rod reaches the disc.
Overhead Sewer System
The better option is usually to re-configure the system to an overhead style. Depending on the current layout, this can be performed by separating the lower level sanitary waste into a sanitary pit, and pumping the waste discharge into the sanitary system, above the sanitary head or high water level.
In this system, the sanitary pit and pump are installed indoors so less maintenance is required, and there is nothing installed in the service line that has potential to get stuck or obstruct the line.
There are specific requirements based on the configuration and condition of the existing system, as well as certain local government regulations that can hinder this type of installation, but these are usually minor obstacles. The biggest concern with this system is the specific layout of the existing sanitary system, and the space needed to install the sanitary pit inside the building.
If you have been experiencing back-ups due to sanitary system flooding, there is a way to protect your home. To better understand your options and to receive an analysis of your sanitary system configuration, please call us to schedule an appointment. There is no charge for the analysis.
We always look forward to helping your with your plumbing needs.