I’m in the middle of one of those super-fun sewage problems, the kind where it doesn’t drain like it should.
Long story short, we finally figured out that there was a massive root blockage in the system. It’s on its way to being fixed, but seems to be one of those things that happens with older (aka 1905) buildings.
I totally understand how tree roots have no problem worming their way into the joints between 100-year old clay pipes, especially when the pipes are joined in 2 feet sections and held together with mortar. So, how do we do it in the modern era? Are tree roots as big a problem with modern materials? What’s the gold standard for sewage drainage with new construction?
The customer’s line to a sanitary sewer is called a lateral, and depending upon the age of the house and local codes, it may be/have been constructed of various materials. Unions may have formally or informally influenced the types of materials used in certain areas as well. Provided that the soil conditions and aboveground use are appropriate, and it meets the local code, plastic pipe is a good choice for small diameter customer connections to both sanitary and storm sewers. Plastic pipe is lighter and generally easier to install than iron pipe and does not rust, but more care must be taken in trenching and solidly supporting the pipe, as plastic can be more brittle.
The fact that you had a tree root invasion related blockage is unfortunate, but it is a part of life for owners of old homes. Also, depending upon whether the home is located in a combined sewered area or a separately sewered area, there are different sources of back ups and different exit paths for suface water runoff. Your local water and/or stormwater drainage utility is probably the best resource to answer these questions.
There are various root killer formulations on the market that MAY help in ceratin situations, but rarely in the case of abrupt complete blockages like you are describing. You the homeowner are responsible for confirming which drains and/or fixtures are attached to the line prior to using these chemicals. If there is a good access point, short distance to be cleared, or obvious source of blockage, you may also try hand, power drill, or bespoke power operated drain “snakes” for clearing the line, but it may be more efficient to employ the services of a professional rather than purchase or rent this equipment.
Joints are not the only way for roots to invade. Really old systems are liable to be made of clay pipes and newer ones of concrete. Both of those are susceptible to roots simply burrowing through them as the material interacts with water in the soil. I suppose that more recent ductile iron and polyvinlylchoride and related materials are less susceptible, but iron is extremely expensive as a solution to a problem that can be addressed mechanically (“Roto-Rooter™” and similar machines) every few decades. (I do not know whether the plastics are the best solution, or not, but the plastics that will not degrade in soil and water are still fairly new, so we don’t have 100 years of history to determine their value. (The original plastics would degrade and turn brittle in water-soaked soil.)
One preventative measure is to paint the entire pipe with tar or mastic to prevent both rot and invasion, but that is hardly a cheap solution.
The laterals in my house are all made with ABS pipe. The joints are made with ABS adhesive and the whole system is much more imperfious to roods than transite, or clay or any other pipe with mortared joints.
Local plumbers and the public utility alike are using modern plastic pipe for all undergound and in the house lines.
High pressure plastic is also used for both hot and cold water lines as well as radiatant heating installations.
Thieves of copper piping are thus thwarted :smack: and consequent water damage greatly diminished.
In our area PVC (poly vinyl chloride) pipe is used for sanitary sewer lines. The lateral from the house to the main is usually 6” diameter and the main starts at 8” diameter but can be larger if more area (and houses) drains through it.
The PVC pipe usually comes in 14’ or 20’ lengths and fit together tight enough with rubber gaskets that seepage won’t occur. It the seepage that can attract roots seeking out the nutrients in waste water. Our specifications call for testing of lines to be done after installation. A section of installed pipe is pressurized by air to 4 psi above atmosphere. Not much, but enough to see if there are leaks.
Gaps can occur by poor installation and this is where problems arise. Last year the short sanitary line running between my house and septic tank kept getting roots growing. I finally dug it up and found out that the installer had not compacted the ground under the pipe enough. This allowed the pipe to settle and it pulled apart a little at a 45 degree bend. The resulting gap allowed the roots to enter and clogged up the pipe. I replaced the pipe, made sure the supporting ground was compacted, used pipe glue to attach the 45 degree bend and have not had problems yet.
PVC pipe seems to be working well for the industry. I can’t recall when it began to be used, but it has been longer than 25 years. Come to think of it, I’ve seen some pulled out that was around 30 years old and it was still doing well. Dirty and stained but not corroded.
I feel your pain, by the way - I just had to replace everything from the house to the street a few months ago. Expensive, backbreaking labor by my plumber, and extremely difficult because the property lines have changed dramatically since the pipe was installed and he couldn’t just follow it through the neighbor’s yard to where it needed to go. He may never speak to me again.
At least some cities still require the use of cast/ductile iron for lateral connections. I checked the Philadelphia plumbing code today to confrm this. I think Chicago was holding out longer as well, but they may have adapted the plastic in the last few years or so.
Most areas here in New England use 6-inch SDR-35 PVC pipe for gravity laterals, and 8-inch SDR-35 PVC pipe for gravity mains. Sometimes 10-inch SDR-35 PVC pipe is used for larger mains. Specially-lined ductile iron is often used for the last run of gravity sewer leading into a pumping station wetwell from the last manhole.
Force mains are generally ductile iron, C-900 PVC pressure pipe, or HDPE pressure pipe.
Low-pressure sewers are generally HDPE pressure pipe.
