Your Building’s Drainage System: How it Works and Repair Options

//Your Building’s Drainage System: How it Works and Repair Options

Understanding Sewer Repair For Condominium Buildings

Was your condominium or apartment building built before 1985? Are you experiencing regular toilet stoppages and backups, tree root intrusion, or sewer odors? If so, the long-term solution is NOT having your sewer lines snaked every few months.

Property Managers, HOA/Condominium Board Members, and home owners face a real challenge today, especially in areas where a large majority of condominiums are built prior to 1985 such as South Florida. The older the building, the more property managers and board members need to be aware of the infrastructure systems within the building. As we know, EVERYTHING needs to be maintained. This article will highlight the basics that you need to know about your building’s drainage system – how it works, common types of pipes, and what your options are for repair.

Did you know?: The structural integrity of your building’s sanitary drainage system is NOT inspected during 40 year recertification inspections. (source:

Understanding Your Building’s Sanitary Drainage System

In a multi-story building such as a condominium complex, the sanitary drainage system consists of three main components – vertical stacks, branch lines and horizontal underground lines.Condominium Sewer Pipe Repair

Types of Vertical Stacks

Stacks are vertical lines of pipe that extend from the horizontal building drain under the slab or in the basement up to and through the roof of the building. Although the general direction which these pipes run is vertical, they may be offset or run in a horizontal position on upper floors and still be identified as a vertical stack. In the industry these pipes are either known as soil stacks, waste stacks, or vent stacks depending on the purposes which they serve.

Soil Stacks

The distinguishing factor that gives soil stacks their name is that they receive discharge from water closets and urinals. Clean water fixtures such as sinks and showers may also tie into soil stacks.

Waste Stacks

Waste stacks are tied into clean-water fixtures only – such as sinks, showers, bathtubs, lavatories, and the like. Waste stacks never receive waste from fixtures such as water closets or urinals. If a fixture such as a water closet or urinal was ever tied into a waste stack, it would thereupon become a soil stack.

Vent Stacks

Vent stacks carry no liquids. Their role is to provide airflow through the drainage system so that when water flows through branches and stacks the traps will not be forced by back pressure. The portion of a vertical stack that is above the highest fixture tie in becomes a vent stack.


Rain leaders are vertical stacks in that they extend from the horizontal storm drain or combined sewer drain to the roof. They are called rain leaders because they transport rain water only.

Branch Lines

Branch Lines are offshoots of vertical stacks, like branches of a tree. These branch lines connect toilets, showers, sinks, washing machines, dish washers, etc. to the corresponding vertical stack, which carries waste to the building’s drain underground or in the basement.

Horizontal Underground Lines

Horizontal Lines run underneath the building’s slab, often under common areas such as the lobby and individual ground floor units. These lines are typically 6-8″ in diameter depending on the size of the building. Since sanitary drainage is gravity powered, underground main lines are slightly pitched to carry waste away from the building into the city sewer. The horizontal pipe that receives discharge from waste and soil stacks and is located within the buildings footprint is called the “building drain” and thereafter is known as the “building sewer”.

Common Types of Pipes in Your Building

Here in South Florida the most common pipe used in sanitary drainage in older buildings is cast iron. Next up is clay. Newer buildings however, are often built with PVC. Here is a brief overview of these different piping materials.

Cast Iron Pipes

cast iron pipe crack

Cast iron sewer pipes have a life-use expectancy of 25-35 Years and then they begin to develop cracks and channels. (photo source:

Cast iron piping is still by far the most common material used for sanitary drainage in multi-story buildings such as condominiums and apartment buildings.

Here are some key advantages of cast iron pipe that come into play:

  • Cast iron drainage pipes offer durability and can support 4,877 lbs per linear foot.
  • Cast iron piping reduces noise due to its density, which is an important selling point for condominiums, apartment buildings and hotels.
  • Fire-resistance is another key factor of cast iron pipes as they will neither burn or contribute to the spread of fire.

The main disadvantages include:

  • Cast iron piping is expensive.
  • Cast iron has a relatively short lifespan of 25-35 Years (in South Florida).

After cast iron’s expected life-use of 25-35 Years in South Florida, the pipes can be expected to begin developing channels in horizontal lines and cracks in both horizontal and vertical lines. Buildings in close proximity to the ocean experience accelerated cast iron pipe deterioration due to the salt in the air which is pulled down the vent stacks and the fact that the underground cast iron pipes are often submerged in salt water twice a day with high tide. Salt and cast iron is a corrosive combination. Cast iron piping, however, is often still favored over PVC in condominium applications due to the advantages listed at the outset.

Vitrified Clay Pipes

clay sewer pipe repair

Vitrified clay piping dates back to 4000 B.C.E., however is rarely used today. – – (source:

Clay sewer pipes are most common in historic homes and buildings. Vitrified clay sewer pipes have been in use since ancient times with the earliest known example dating back to Babylonia, 4000 B.C.E.

Advantages of vitrified clay piping include:

  • Durability
  • Chemical resistant material for sanitary drainage

However the disadvantages of clay pipes include:

  • Clay is very susceptible to tree root intrusion as the porous outer surface is easy for roots to attach to
  • Very heavy and hard to cut
  • You most likely will not find it in your neighborhood home improvement store.


PVC Piping

PVC sewer pipes

Studies suggest that PVC pipes have a service life of 100 or more years. (source:

Starting in the 1970’s PVC pipes began to be installed in mass quantities. Cast iron proponents would say that not enough time has yet elapsed to determine the service life of PVC, however, studies suggest a 100-year or more lifespan for PVC. (source:

PVC versus Cast Iron has been a hot topic in the pipe manufacturing industry for years. However certain advantages are clear and include:

  • Longevity
  • Cost efficiency

However certain disadvantages are clear as well and include:

  • Non fire-resistant, additional fire-stopping measures required upon installation.
  • Carcinogenic fumes when exposed to excessive heat.
  • Not as strong as cast iron.
  • Noisy water transportation (not ideal for multi-story residential buildings such as condominiums and hotels).

Conventional Sewer Replacement

Conventional Pipe Repair

Conventional pipe replacement requires access to the old pipes by means of trenching floors and tearing out walls.

Conventional pipe replacement is a MAJOR undertaking for condominium buildings. Now that you understand where the pipes run in your building and know the typical lifespan of cast iron pipes, you may have an idea what would be involved with replacing those pipes traditionally, tearing out walls, tearing out custom floor finishes and slab, relocating tenants, extensive mess, expense, etc.

Trenchless Pipe Lining Sewer Repair

Pipe lining – also known as Trenchless Pipe Lining, C.I.P.P. (Cured-In-Place-Pipelining) – is the process of repairing sewer pipes without digging or destruction. In a nutshell, an epoxy saturated felt liner is inserted into the pipe which is inflated, cures in place and leaves behind a brand new pipe.


The advantages of trenchless pipe lining include:

  • Sewer repairs to be made without tearing out walls or floors
  • Saves your building 30-40% of the cost of traditional sewer replacement
  • Trenchless sewer repair allows for residents to stay in their home during repairs
  • Can be completed in a fraction of the time involved with traditional sewer replacement.

In South Florida, we deal with many condominiums built as far back as the 1960s that have cast iron and have not yet set aside a budget for repair. If your building was built before 1985, you need to start budgeting for pipe repair now to avoid dishing out costly assessments in the case of sanitary sewer failure. Your first step to diagnosing the condition of your sanitary sewer would be a comprehensive video inspection. If you are within our service area in Southeast Florida we would be happy to provide you with the needed assistance. Call Pipelining Technologies today at 561-412-4234 or click here to contact us!

By |2018-01-24T14:51:30+00:00November 11th, 2015|Condominium|40 Comments


  1. RJ May 25, 2016 at 6:09 pm - Reply

    The good and bad. I live in a condo where we had this process done. Unfortunately, I didn’t realize that the branches that lead up to the sink toilet, tub were not part of this. Thus this past week I discovered the drain behind my kitchen sink was leaking into the wall and had been apparently for some time. I ended up cutting away the gypsum to discover the pipe had deteriorated with age to break all the way through. The video’s focus on the largest part of the drainage, but don’t address what can cause potentially the most unseen damage, until it has gone on for much too long.

    • Parker Ruiz August 2, 2016 at 11:50 am - Reply

      Lining is great for main runs but not the areas you mention such as waste arms in the wall. In a condo typically the common lines are lined (association responsibility) but not the unit owner’s piping. Therefore, it is important to replace these pipes when remodeling and know the warning signs to look for such as this article mentions.

  2. judy wilson June 29, 2016 at 4:52 pm - Reply

    I didn’t realize how there are so many different types of stacks involved in drainage systems. It’s interesting how vent stacks provide airflow through the drainage system to reduce pressure while water is flowing through other stacks. It’s good to know about this in case something is causing excess pressure through branches in drainage systems.

  3. Norm W August 16, 2016 at 1:41 pm - Reply

    I live in a condo and my guest bathroom sink drain is tied into the kitchen drain of an adjacent apartment before it enters the main building drain line. A continuos problem occurs when the drain tie point becomes clogged with deposits from the garbage disposal unit. Is this a legal hookup? This building is in New Jersey, and was built in 1974.

    • Parker Ruiz August 29, 2016 at 9:08 am - Reply


      We only service South Florida, so you would be best served by reaching out to a Licensed Plumber in New Jersey for questions on local legalities. Thank you for reading our blog!

  4. Dima February 9, 2017 at 7:55 pm - Reply

    Please Help
    I leave in a condo for 13+ years. About 6-7 years ago the Board picked my floor with 3-4 other ones to install
    Clean-outs. I objected to, but had no choice they said; one was installed in my hallway. The clean-out process was to be done every other year. The previous few years the clean out process (about half hour) became yearly. This year was done in about 7 months. This means I have to provide access to my suite in order to do the work. This creates a lot of problems lately accessing my suite. Management expects to use my suite as an “open house” type. The board appear to go along with management. I don’t like moving out, or spend large amount of money in legal fees. What are my options?

    • Parker Ruiz February 16, 2017 at 4:58 pm - Reply

      Hi Dima,

      Unfortunately, we cannot offer legal advice. However, it does sound like there are ongoing plumbing issues that have built up to this point and our advice would be to ask the Board to consider a through video inspection of the system to try and assess the overall condition of the plumbing system and begin to take measures to develop a plan to permanently line or replace the pipes.

      Thank you for visiting our blog!

  5. Tierra A February 13, 2017 at 9:50 pm - Reply


    My landlord is experiencing flooding from the sewer line in the apartment below mines. He claims that the blockage is coming from my unit and causing the seepage in the unoccupied unit below and is asking that I pay for half. It should be noted that the below unit has been vacant for years, the water seepage has occurred in the past, and that my toilet has been stopped before but nothing that a plunger couldn’t fix. Now based on your drawing above, if there is a blockage caused by me, between the two floors, wouldn’t I be experiencing the same flooding? Isn’t it possible that the blockage is preexisting and is between the below unit and the main?

    • Parker Ruiz February 16, 2017 at 5:02 pm - Reply

      Hi Tierra,

      An inspection would need to be made by a qualified plumber. There are far too many variables to offer any speculation.

      Thanks for visiting our blog!

  6. Jeanette April 18, 2017 at 9:36 pm - Reply

    Great video! It has answered all my questions about how the process actually works and how holes are made for secondary lines.

    Our condo is from 1959 and we are starting to see major problems from our drain lines. We are hoping that this could be used to avoid tearing out units bathrooms.

  7. Drain laying in Christchurch July 21, 2017 at 1:08 am - Reply

    Great idea. I like your tips. It is very informative post. Your blog is very useful for every people. I would definitely try to maintain the drain cleaning in spring. Thanks for sharing this idea with us.

  8. plumbriteinc July 27, 2017 at 2:53 pm - Reply

    I read your post. This is the first time I am seeing your full post. Awesome writing. It’s really helpful. Thank you so much for giving the important information.

  9. dan bennett August 29, 2017 at 3:06 pm - Reply

    Looking for answers that aren’t supernatural. I live on the 2nd floor of an 8 story building, maybe 100 units all together. There are laundry facilities on the 8th floor.

    My toilet is possessed by a very clean ghost. It flushes itself, with a roar, and fills with soapy water! Completely baffles the maintenance crew. No one’s heard of it before. Something with the vent stacks, maybe?

    Anyone come across this problem before?

    • Craig Underwood
      Craig Underwood August 29, 2017 at 3:38 pm - Reply

      Sounds like a venting issue to me. Somehow the laundry stack is choked for air and pulling from the bath stack. Perhaps the toilet is tied into the laundry stack somehow and the laundry suds are too much and choking the venting. Make sure that if the laundry machines are “HE” machines that only “HE” detergent is being used.

  10. Max Sayer September 21, 2017 at 7:27 pm - Reply

    Building and understanding the drainage system of your home and yard is crucial. My home’s yard drainage is pooling by my driveway and cause the driveway to settle and cause bad cracks. I’m keeping this in mind when I address this in the spring.

  11. Lynn Gu September 26, 2017 at 12:32 am - Reply

    Hi, I just bought an apartment and it’s under renovation now. The management requires me to change entire branch vent and branch line which connects with bathtub, sink and toilet to soil pipe and partial soil pipe. Shall these be my responsibility to change it or building’s responsibility? Is it a big project since my contractor refuse to do it?

    • Craig Underwood
      Craig Underwood September 26, 2017 at 7:13 am - Reply

      You would have to read your by-laws to be sure, but general rule of thumb is if it serves multiple units it is the association and if only yours then you are responsible.

  12. Jay Ren September 30, 2017 at 8:31 pm - Reply

    I didn’t know that cast iron pipes had such a short lifespan. The apartment building I live in boasts about their cast iron piping systems, but I know the building is quite old. Would they be breaking regulations if their pipes, floor drains, or other parts of their plumbing are outside of their expected lifespan?

    • Craig Underwood
      Craig Underwood October 2, 2017 at 7:50 am - Reply

      Cast iron has different life expectancies in different regions of the country.

  13. Naim October 17, 2017 at 2:32 pm - Reply

    Hi , thank you for this . I receceny purchased in an apartment in an old complex but was built in the 80’s. The pipes in the complex all make a noise , the apartment above when they in the shower or my neighbor on the same floor next to me. What can be done to stop these noises ? I’m told by the trustees that’s how the whole complex is , had I known I wouldn’t have bought here. The sound of water flowing through the pipes all the time is new to me . What can be done to correct the noise ?

    • Craig Underwood
      Craig Underwood October 17, 2017 at 3:23 pm - Reply

      PVC pipes are more noisy than cast iron and the walls are probably thin. Adding sound barriers like insulation is your only real option.

  14. Michael Solow December 7, 2017 at 10:09 am - Reply

    I live in a condo building. I began to experience poor draining of my water closet n one of my bathrooms. Is there a video of how the water sink, tub and toilet waste lines are tied together. Tub and sink are draining but the water closet is very slow and gurgling. I had plumber check it out . He dismantle the water closet made sure it’s not blocked, run snake and pulled some hair and paper towels, reasamble it, it worked for one day and now it’s backing up. I live in Miami

  15. Jaque Christo December 11, 2017 at 9:17 am - Reply

    Thank you for the information on a buildings drainage system and how it works. The trenchless technique where you inflate an epoxy saturated felt liner to repair the piping sounds very interesting. I wonder if that is commonly used or something that has only recently been tried and tested?

  16. Becca Holton January 10, 2018 at 4:18 pm - Reply

    I agree that snaking your drains every few months isn’t too helpful. It’s temporarily helped the drain problems in my bathroom. However, I’ve been thinking about how it’ll save me time to have the problems in my bathroom solved by a professional.

  17. Joy Butler May 2, 2018 at 7:35 pm - Reply

    I appreciate you helping me learn more about the drainage system. At first, I thought that it’s a complicated process, however, after reading this post, I fully understood how it works. I noticed that among the common types of pipes you’ve mentioned, cast iron piping has only 2 disadvantages to which I think have nothing to do with its performance or function.

  18. Sarah May 28, 2018 at 11:41 am - Reply

    Hello I am from MA and our bathroom sink drains slow. We have looked everywhere imaginable to see were it drains to and have not been able to find it. Could this be conected to the kitchen sink drain or the toilet and run between the wall that is between our kitchen and bathroom?

    • Craig Underwood
      Craig Underwood June 4, 2018 at 4:47 pm - Reply

      It will run down the wall and tie in underground. A video inspection can locate the tie in.

  19. Roberto Rosenfeld June 3, 2018 at 11:15 pm - Reply

    Two questions if I may,
    a) how many more years will this process add to already old cast iron pipes?
    b) following the above, if the cast iron pipes have already shot through their 35 years life expectancy, wouldn’t the pressure from inside lining finally crack the pipes for good?
    c) what are the major risks of this process, or, when would this process NOT be recommended?

    • Craig Underwood
      Craig Underwood June 4, 2018 at 4:46 pm - Reply

      A. Adds a life expectancy of 50 years to the existing cast iron pipes.
      B. No, we use the pipe as a channel, you will have a new structural pipe created inside the old pipe once done.
      C. Pipe lining will not correct pitch issues so if you have back pitch you will need to replace.

  20. Glenda householder July 3, 2018 at 9:55 am - Reply

    I live on the first floor of a 3 story appartment. My kitchen sink has backed up 3 times in six years and now my landlird said I have to pay for it if it happen again. I feel the problem is coming from the apartments above me. Aren’t they staked and use the same drain?

    • Craig Underwood
      Craig Underwood July 9, 2018 at 7:32 am - Reply

      They are, but the problem may lie in the main line or just in your waste arm. If it backs up again and a plumber comes to clear it ask him where the blockage is and that will determine responsibility.

  21. Mare August 3, 2018 at 12:30 pm - Reply

    I live in a condo and my neighbor is renovating his bathroom. His bathroom backs up to my bathroom which makes sense. Anway, during the renovation, the pounding and crashing was violent that the pictures in my living room nearly fell off the wall. Now our bathroom smells like a sewer. Could all that pounding have damaged the vent pipe?

    • Craig Underwood
      Craig Underwood August 7, 2018 at 9:20 am - Reply

      Possibly, or a no-hub could not be tightened. A smoke test will reveal the cause.

  22. Ellen Hughes September 11, 2018 at 12:58 am - Reply

    It sure was nice to know that rain leaders can transport rainwater and can be combined sewer drain to the roof. My father is looking to have his house remodeled. He said that he wanted to install a stormwater system that will work effectively to prevent his yard from getting clogged and flooded because of the rain. Thanks!

  23. Matt Brown October 16, 2018 at 12:01 am - Reply

    I am trying to a plumbing all by my self because it cost a lot to get a service. Using all this kind of tips are so helpful since I am trying to do the repair all by my self. Thanks for the Awesome tips.

  24. Terry October 21, 2018 at 6:41 am - Reply

    I have a condo on the first floor of a three story building. I believe the building was built in 1979. The association hydro jets the pipes once a year. The washing machine, kitchen sink, dishwasher, toilet/shower are located alone the same side of the unit. I first experienced drainage issues with the washer. Maintenance put a snake down the drain and said it was clear so must be the washer. I’ve since discovered it will only work on two of the cold water settings. Not long after, the dish washer had drain issues. Maintenance came to unclog drain. I asked if it has anything to do with the washing machine issue and he said it’s just a coincidence. We’ve used the dishwasher only a few times since, and noticed that water came out of the spout on the kitchen sink. We never had a dishwasher in our prior apartments and thought it was normal since we just had maintenance fix it. Then today I decided to replace my water filter under the sink. I first turned off the cold water. Maybe I wasn’t supposed to do this, but I used the hot water in the sink to wash the filter housing. I figured it would be okay thinking that the hot water had nothing to do with the cold water line anyway. However, I was surprised that the hot water started to drip through the cold water filter tube that was disconnected at the time. I had noticed recently that the water from the filtered water faucet seems a bit warm. How is this possible? Why is the hot water all of the sudden coming through the cold water line? And could all these issues be related? How do I know if water/drainage from all these fixtures are somehow crossing over and/or possibly combining water from the waste and soil stacks where they shouldn’t. Any advice or clarity you can provide is appreciated. Thank you!

  25. Malia Davis November 6, 2018 at 11:21 am - Reply

    It’s awesome that cast iron pipes are so durable and able to hold so much weight! We need a nice, solid option for our home’s plumbing system because I don’t want to have to do maintenance on the system too often. We’ll have to find a good plumber in our area that could help us make sure cast iron is the right option for our home. Maybe they could come over and inspect things first to give us an accurate recommendation.

  26. Ivy Heaton November 26, 2018 at 6:48 am - Reply

    I live on the third floor of an apartment building, and I’m facing regular problems with my bathroom drainage. As the building management was rather uncooperative, I finally got a pipe repair done myself. Best decision I’ve ever made.

  27. Jensen Mott November 29, 2018 at 12:00 pm - Reply

    It’s good to know that cast iron pipes are not flammable and won’t contribute to a fire! I want to avoid any chance of having a house fire because I’ve seen how devastating they can be. We are trying to get our home repiped, and I think cast iron will provide the durability we need for years to come while being fire resistant! I’ll talk to a pipe specialist and see what options they have for this.

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