Why Your Main Line Backs Up Every Year at About the Same Time

If your main line backs up at roughly the same point every year, that is not bad luck. It is a schedule, and the thing keeping it is a tree.

The older parts of San Jose, including Willow Glen, the Rose Garden, Naglee Park and the older streets in Campbell, were plumbed with clay sewer laterals laid in short sections, which means a joint every few feet. Clay is a perfectly good material and plenty of it is still doing its job. The problem is the joints. Roots do not smash through pipe; they find a joint that has shifted slightly or a hairline crack, follow the moisture, and go in as something no thicker than a hair. Then they grow.

What grows inside the pipe is closer to a net than a plug. Everything that comes down the line catches on it, and the blockage builds until one day the line will not pass any more and it comes back up at the lowest fixture in the house. That is why it tends to be a downstairs shower or a floor drain that shows you first.

The seasonal pattern is the giveaway. Roots grow when the tree is growing, so backups often cluster around the same part of the year. If you have called somebody out in roughly the same month two or three years running, you are not dealing with separate incidents.

Clearing it works, for a while. A cable with the right head on it will cut the roots out and the line will run properly again. What it does not do is stop them coming back, because the way in is still there. Anybody who tells you a single clearing has permanently fixed a root intrusion is either being careless or is hoping you do not remember the conversation next year.

The camera is the part worth paying for. Once the line is clear, running a camera down it shows what you are actually dealing with: whether it is one bad joint or twenty, whether the pipe still holds its grade or has a belly collecting water, and whether there is a section that has cracked or dropped out of line. Those are completely different problems with completely different price tags, and you cannot tell them apart from the top of a cleanout. We would rather you saw the inside of your own pipe and made the decision yourself.

From there it is arithmetic. One bad joint on a line that is otherwise sound is a spot repair. A lateral that is failing along its length is a replacement, and replacement is where trenchless methods can save your driveway and your planting, though not on a line that has collapsed or lost its grade, in which case it has to be dug. Some people quite reasonably decide to keep clearing it every couple of years and spend the money elsewhere. That is a legitimate choice as long as it is a choice and not a surprise.

What we would ask you to do is stop treating each backup as a one-off. Get it cleared, then get a camera down it once, and decide from there. More on sewer and main lines, or on drain cleaning if it is only one fixture giving you trouble.