The Sewer of the property has two parts- the waste line that runs underneath the house, and the sewer line running from the house to the public sewer mainline in the middle of the street.
As a property owner you are responsible for maintaining the sewer line from the tap all the way to your property. Some owners are surprised by this, because the tap is located underneath the pavement in the street and you would think since the street is government property that the sewer line underneath it would be too. This is not the case. Often times during a sewerline camera inspection the camera will reach a blockage in the line that prevents you from reaching the city tap. It might be tempting to just assume that everything is fine, but I strongly recommend having the seller snake ($150) or hyrdojet ($600) whichever is appropriate and do a reinspection when the line has been cleared. The last portion of the sewerline that connects to the city tap is by far the most expensive if a repair is needed. This is because you will have to dig up the street to get access! Expect a repair on this portion of the line to cost $10,000.
There are three common sewer line problems:
Tree roots search for water. Tree roots shoot out little tubers that are drawn toward damp areas. These roots can penetrate the sewerline at its weak point, the fittings, and grow within the sewer line, clogging and blocking the line, and also crack the fittings or create a break in the line. If you have large trees in the front yard of your property, especially ficus, there is a pretty good chance that you will have root intrusion in your sewerline.
The sewerline is a gravity driven system. The line must have at a minimum, a continuous negative 2% slope that runs downward all the way to the public sewer. Water doesn’t flow uphill. When the sewerline gets shifted for whatever reason and lays flat or even has a positive grade, this creates a belly in the line. Water and debris backup at a belly and can clog the line. Some amount of belly is expected. ABS pipes tend to have more bellying than other materials because they are flexible. There is an advantage to ABS being flexible, they resist breaking during earthquakes better than clay or cast iron.
Fittings run every 10 feet or 20 feet, so on a 100 foot line that is 5 to 10 fittings. This is the weak point in the line so when you have a break it tends to be here. The problem with having a cracked fitting is that waste water from the house is going to leak from the fitting into the ground. The leaking of sewage materials into the ground contaminates the soil. Storm water from rainfall or watering your lawn will also run into the line. The city requires you to fix all cracked fittings because having storm water drain into the public sewer overflows the system. There is a separate storm drain system that channels away rainwater into the Los Angeles River and out to the ocean. The sewer line system runs to waste water treatment plants.
Types of Pipes
There are three types of piping- vitrified clay, cast iron, concrete, and plastic (ABS).
Cast Iron pipes are painted black, and have “hub” fittings.
If you find a major problem that requires the sewerline to be replaced, such as a fractured or collapsed pipe there are three options for repair:
Digging out a trench and replacement, Trenchless sewerline replace, or a liner system.