Why do I have a large sewer vent in my backyard?
That tall pipe standing in the garden, along the fence or up the side of the house, sometimes with a cowl or grille on top, is a sewer vent. Every drainage system needs air moving through it so water drains freely and sewer gas goes up and away, rather than coming into your house. In older Sydney homes, these vents are often bigger and more noticeable than in new ones. Here's what they do.
What a sewer vent does
Lets the drains breathe
As water flows down the pipes it pushes and pulls air. The vent lets air in and out so drains don't gurgle or drain slowly.
Protects the water seals
Without a vent, draining water can suck the water out of traps under sinks and showers, letting smells in.
Carries gas away
Sewer gas rises up the vent and is released high above the ground, away from windows and people.
Older boundary trap vents
Many older homes have a boundary trap near the front or back of the property, with its own vent pipe. These are common in the Eastern Suburbs.
What not to do
- Don't remove, cut down or cap a vent pipe. Drains will gurgle, smell and drain slowly.
- Don't block the top with a bag or tape to stop smells. It makes things worse inside.
- Don't build a deck, pergola or window close to the top of a vent without checking the required clearances.
If the vent smells
A faint smell near the vent on still days is normal, as that's its job. A strong smell around the house, or inside, usually points to a dried-out trap, a damaged vent or a blockage further down. We can check the vent, the traps and the drains, and move or extend a vent where it's in an awkward spot, with a fixed price before any work starts. See gurgling drains.
In southern Eastern Suburbs homes
Older homes in Matraville, Maroubra, Kensington and Kingsford often have tall cast iron or earthenware vents, and boundary traps with vents near the fence line, from when the sewer was first connected. They still do an important job, so keep them in place.
Why locals call us
- Local to Matraville and the southern Eastern Suburbs
- Free on-site quotes, with a fixed price before any work starts
- Lifetime labour warranty on our workmanship
- 100+ five-star Google reviews
- Licensed plumbers and gasfitters (Lic. 398171C)
Common questions
What is the tall pipe in my backyard?
Usually a sewer vent that lets air into the drainage system and releases sewer gas high above the ground.
Can I remove the sewer vent pipe in my yard?
No. Removing or capping a vent makes drains gurgle, smell and drain poorly. It can be relocated by a licensed plumber in some cases.
Why does my sewer vent smell?
A slight smell on still days is normal. A strong or constant smell may mean a damaged vent, dried-out trap or blockage.
What is a boundary trap?
A trap on the sewer line near the property boundary, common in older homes, often with its own vent pipe.
Related help: gurgling drains, traps explained, manhole in the yard, sewer responsibility guide and blocked drains. Local pages: Matraville, Maroubra, Kensington and Kingsford. Browse all our plumbing guides.