Want Pipes That Suck Less? Avoid Gross Outbursts When You Let That Plumbing Vent

Plumbing fixtures like sinks, baths and toilets need to vent sometimes. Gasses from human waste and other materials need to escape your pipes. Suppress these and you end up with bad odors, poor drainage and the possibility of a nasty system blowout.

If you're experiencing chronic plumbing odors, gurgling pipes or backed up sewage from time to time, your vents may need to be inspected and repaired or replaced. Here's what you should know about vents.

All plumbing vents must head outdoors

A properly-vented plumbing arrangement in a home will include an air vent pipe attached at that snaky-looking pipe (called a trap) under the sink at the drainage point of every plumbing fixture. The vent pipe is placed so that only smelly air, not waste water, should enter the pipe to be carried out of the home via the venting system.

These small pipes feed into a larger diameter pipe that generally will vent out of the rooftop in most homes. Larger homes may have several roof-high plumbing vent pipes fed by the tubs, sinks, toilets and showers, although plumbers try to consolidate them to avoid placing too many holes in the roof.

Some shoddy plumbing jobs feature vent pipes that open up under the sink or behind walls, feeding the noxious plumbing gasses back into the home. Inspect your plumbing vents to be sure they are properly vented to the outdoors. If they are not, have the vent pipes properly installed to avoid smells and other drainage issues.

Adding new wet islands or plumbing fixtures may require bow vents

If you're remodeling a kitchen and want to add an island with a sink or another plumbing feature that requires a vent, you can tie into the existing system with a bow vent, which is basically a short, under-cabinet arch that vents air up and over the arch then down to a floor air vent that ties to the main system. This may also be a solution if your venting system is not correct and you need an easier way to tie into the existing system.

Installing a bow vent is tricky, since water can back up more easily into the floor air vent if there is a drainage problem. Installing a relief drain off of the bow vent, and making all of your pipe connections up to code as far as height and pipe circumference should help you avoid these issues.

For example, the final connection from the new sink to the main air vent pipe must be made higher than the new sink height so that if the sink backs up, the water will never reach the air vent. It sounds complicated, and it's true that installing vents requires some serious attention to detail, so hire a professional if you have doubts about your skills.

Check vents after storms and other events

After debris or heavy rain falls on your roof, check your roof plumbing vents to be sure there are no blockages or other issues. Most roof vents are capped off with sturdy protective covers and watertight seals, but high winds, ice or heavy snow loads can damage the caps. Animals or insects may also decide to invade the vent openings.

It's possible to flush out your own plumbing drains through the vents if they become clogged, but you may want to call in professional plumbers if your vent caps or pipes are severely damaged. Heavy blockages may require special equipment to suck out debris or other vent and drainage pipe contaminants.

When you have a new roof installed, make sure the crew takes care around your vents and that the roof is properly sealed around the vent opening. This is also a good time to inspect your roof vents for any damage.

Without properly-functioning vent pipes in your plumbing system, every flush of the toilet can siphon waste water into sinks or tubs. Avoid these gross outbursts by letting your plumbing have some breathing room. Before you install any new plumbing fixtures, make sure you understand how to safely vent them into your system. It's best to contact a professional plumber for more info if you want to be certain your work is up to code.

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