What Is a Soil Stack?

Soil stack are part of the pipe system of plumbing that joins inside pipework to the drain, and lets out gases from the building. The pipes can be present in any kind of building however, they can be found present in almost every home or small-sized building. When a system utilizes soil stacks it is a vertical pipe that extends from beneath the building until it reaches a vent on the roof. These pipes that are vertical are identified by a sporadic whooshing sound when waste water flows down from the upper drain.

When water that is discarded from the toilet, sink and bathtub, it is pumped through pipes for waste water to the centrally located soil stack. A majority of homes utilize a gravity-based system and pipes that are used for disposal are always angled downwards to aid in getting rid of waste. After the water reaches the vertical soil stack the liquids and solids move downwards while gases travel upwards.

In the middle of a soil stack you will find an entrance for the waste removal system. This could be an exit for sewers, in the event that the building is located in an urban zone, or an septic tank if the structure is rural. The pipe also slopes towards the downwards direction, just like the waste pipes that are used in houses.

The top part of the stack is typically basically an uninvolved pipe. The vents release gasses to the air, where they are quickly dissipated. Some vents come with covers that block birds and insects from getting entry to pipes however these are not required since the smell alone is enough to repel many animals.

What Is the Difference Between a Soil Stack and a Waste Stack?

To better understand how waste stacks and soil function, let's take a take a look at the greywater system for a second. Greywater is a result of tubs, showers and sinks as well as washing machines and other equipment but not toilets. It's yet to come into contact with water from toilets or feces. This is the reason it's known as "grey." In contrast the water coming from toilets travels an entirely different route. Every toilet has a drain that eventually connects into the stack of soil, but not to the garbage stack.

If you have more than one stack within a drain-waste-vent system greywater is typically directed into the stack for waste. Here's where you can see the distinction in the stacks. They could be parallel to one another, but they aren't touching. In this two-stack arrangement, they drain into the main drain before they move into the sewer.

Another important distinction between waste stacks: the size. Most soil stacks utilize larger pipes in comparison to the waste stacks. With a bigger pipe, the solid waste is able to be more easily drained down the drains of the building towards the sewer. Municipal plumbing codes typically require minimum pipe diameters for waste and soil.