Steps to Repair Common Drain and Vent Problems

A drainage system comprises two key components: drain lines that carry water/waste to a public sewer system or septic tank; and vent lines that permit air to enter the system. The vent lines have vents to equalize pressure in the waste lines and stop air from getting sucked through fixtures in your house.

When plumbing problems arise in the drain lines and vents, they can be quite frustrating because of the limited access. Common problems include:

1. Missing Vent Lines

There are different types of vent piping, including the main vent, branch vent, fixture vent, and a few more. When properly connected, vent lines should remain free, so any stoppages in the drain piping can be indicated by waste backing up into the fixture.

When there’s a missing vent line, you should ask a plumber to come and install the right size of vent in the right position. Before any work begins, the plumber must obtain permits because the repair involves opening up a wall to run the vent lines, as well as some roof repairs.

2. Clogging

This is a very common problem, despite the option for water and waste to enter the vent lines. When birds build nests on the top of the vent, and they fall into the pipe, the vents can also get blocked. The vents can also block when leaves and other debris fall inside.

Such problems are best prevented by installing a screen that fits into the top end of the pipe. Alternatively, you can install a mushroom cap that has a gap all around to let air into the pipe.

If the vent is clogged, you have to get up on your roof and insert a snake down through the vent line. You can also use a garden hose to flush the vent line out. If the clog is trapped below a fixture, fill in the drain line and then backup your tub, sink, or toilet.

Another option for homes where the vent runs through an attic is to carefully cut the vent line and then run a snake through the pipe from there. Afterwards, reattach the line with a rubber coupling or PVC coupling using glue. This method is, however, not possible for old homes with copper or cast iron vents.

3. Broken Lines

This problem mainly arises in vents that are placed horizontally. Horizontal venting is sometimes permitted for small distances provided the pipe is pitched towards the fixture it is directed to, so condensation can drain back into the drain line. In some locales, vents are installed at a 45 or 60 degree angle.

You should also watch out for frost clogging in extremely cold temperatures, especially for plumbing fixtures with a small vent diameter, as well as air blockage caused by snow cover.