The storm water system pipes of the bridge.

What is plumbing drain piping?

Your home’s plumbing is a complex system that carries water into the house, removes wastewater and permits venting. Most people are only familiar with the visible parts of the system, but, below eye level, a critical system of drain piping exists that ensures the health and safety of the families that use it. Here’s a closer look at your plumbing drain piping and how to keep the system functioning properly.


Fixture Drains

This is the metal lined opening that allows water to flow out of a bathtub or sink. Often the drain is fitted with a stopped mechanism, which can sometimes develop a problem. These are usually simple to repair to restore normal operation. In some cases, debris or hair can buildup, creating a blockage in the fixture’s drain.



The plumbing drain under your kitchen or bathroom sink generally contains a component called a “p-trap.” This curved section of piping is designed to hold standing water, in order to seal the drain system to prevent sewer gases from rising into the home. This component can become clogged with hair, soap film and dirt, which can cause back-ups in the sink.


Toilet Trap

Toilets have a curved drain pipe build into them. Often, you can see this curved design as you look at the bottom of the toilet from the side. As with the p-trap, this component traps water to prevent sewer gas from rising into the house. The trap can become clogged with waste, undissolved paper and other items and may require snaking or other methods to break through the clog.


Laundry Washer Stand Pipe

Another type of common draining system in the home is the washer stand pipe. The stand pipe carries dirty water from the washer to a curved drain pipe, and eventually to the main drain that runs out of the house.


Branch Drain Lines

The branch drain lines are horizontal pipes that attach to various drains from fixtures in the homes. They are often completely hidden behind walls. These branch lines carry wastewater to the main drain system.


Soil Stacks & Vents

The branch drain lines empty in to the vertical soil stacks, which are much larger in diameter. These then drop down into the main drain line and to the sewer system. The soil stack also has a venting system that maintains equal air pressure within the drain system for proper operation.


Main Drain Line

Finally, the main drain is the largest of the home’s drain piping. It empties into the municipal sewer system or septic system. It is located under the home’s basement or concrete slab.


Regular plumbing inspections can reduce unpleasant back-ups and drain clogs. When you need help with your plumbing drain system, contact Lynn’s HVAC to provide experienced, reliable repairs.


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