Major Differences Between Commercial and Residential Plumbing

Plumbing problems can arise at any time, any where. When a new home, building or high rise is built, the design usually revolves around where the plumbing will be installed. We tend not to think about what we can’t see so it can be hard to notice the difference between commercial and residential plumbing behind your walls and under floors. Running water is necessary in both your home and the office, but what is the difference between commercial plumbing and residential plumbing? Keep reading to learn more!

Commercial Plumbing VS. Residential

Plumbing is plumbing when it comes down to it. The plumbing in a home or in a commercial building usually uses the same materials and they both fulfill the same basic function. Here at 1-Tom-Plumber, our technicians specialize in both commercial and residential plumbing. It does takes some experience and skill to tackle a large commercial plumbing project.

Commercial plumbing is no easy feat. Installations are usually optimized from the project design phase since plumbing fixtures and piping are embedded in walls and floors. The three main differences a technician must consider when servicing a commercial building is a distinction in size, number of floors, and a more complex plumbing system. 


Even smaller commercial water mains are WAY bigger than a home’s 3/4 inch main.

Commercial buildings are generally just bigger, to state the obvious. From office buildings and apartment complexes to retail buildings and high rises, all of these structures need a plumbing system. Because they are typically occupied by more people, they need more pipes and outlets for sinks and toilets. This also means increased demand by employees and costumers which could result in more routine maintenance and emergencies. Commercial buildings also require larger pipes to provide more water since they are occupied by more people than say a four family home.


Multiple floors require plumbing on each level of the structure. In commercial buildings, all branch lines (smaller water lines) stem from one large main line. All branch lines may have to reach as high as 12 to 39 floors which also brings gravity into play. Water pressure has to be strong enough in order to keep the whole system working efficiently.

The pipes used may differ from those used in residential, as well. Larger industrial pipes provide more water to more people. In commercial construction, PVC is prohibited by most plumbing code in all large above ground drains due to its poor exposure to high temperatures. Because of their durability and resistance to corrosion, PEX, copper, and stainless steel are most commonly found in commercial plumbing. This drastically incenses material costs and reduces longevity of a commercial drainage system.

Maintenance and Repairs

Because most office buildings, malls, high rises, etc. operate around normal business hours, repairs and service calls may have to be done in specific times of the day or night. Commercial buildings are usually managed by multiple people meaning the owner of the building is not present during repairs so plumbers must communicate via other methods or with on-site property managers. Larger insurance policies and specific building policies also must be considered with commercial plumbing.

Plumbing Maintenance in High Rises

High-rise design and construction present more than a few special challenges, especially regarding the design of plumbing systems. For plumbing purposes, the term “multi-story” or “high-rise” is applied to buildings that are too tall to be supplied throughout by the normal pressure in the public water mains. These buildings have particular needs in the design of their sanitary drainage and venting systems. Some of the biggest challenges to high-rise plumbing design relate to controlling pressure, proper venting, and drainage.  

Water Pressure

In any commercial or residential plumbing system, pressure is both a friend and a foe. Strong water pressure is needed to push water up multiple floors, but it can also cause pressure at the bottom, exceeding the allowable safe level as limited by code and materials. This issue is solved through pressure reducing valves or creating a pressure zone by branching from the higher pressure riser. The complexity of a high-rise building’s water pressure requires a skilled commercial plumber to sort through a variety of issues that may be experienced. In a normal home, if one toilet isn’t working correctly, you can just use the other one in your house. But with commercial plumbing, an out-of-order bathroom can effect many people in a building.


Many people don’t realize that you need air in your plumbing system to keep things running smoothly. Air is critical to the drainage process because drainage flow is caused by sloping pipes, and the motive force is gravity. Without proper air flow, you may experience slow drain performance or a gulping sound in your fixture. Proper ventilation can be especially tricky when it comes to 20+ story buildings.

When dealing with high-rises, both a drainage stack and vent stack should be present, allowing for pressure equalization and relief throughout the system. Aside from relieving pressure in the drainage system, the vent system allows air to circulate in both directions in response to the fluctuating flow in the drainage system. In many high riser vent designs, where stacks need to offset horizontally on a given floor, a relief vent is required. Proper venting also ensures no hazardous gas enter the structure and allow the sewer to drain without limited pressure.


Drainage and venting issues in high-rise structures are essentially general plumbing problems on a bigger scale. Negative pressure can emerge in drainage systems as a result of defective venting systems, usually the result of blocked or damaged vent stacks. Every fixture, whether residential or commercial plumbing, must be connected to its own drain line, which then intersects with the main line. Water must travel this series of lines before being removed from the high-rise. Clogged drains prevent waste water from freely flowing through lines to the outside where it’s expelled in the septic tank and sewer system.

Because of modern plumbing code, these commercial drains cannot be PVC. Because of cast iron’s weight, it is much more difficult to install on a high ceiling.

Many people won’t question the difference between residential and commercial plumbing, but it is important know your preferred plumber is trained in both fields. This ensures he/she is prepared for any problem that you might run into in your home, office, rental property or even high-rise building. Plumbing is an essential part of our every day life. Safe, running water keeps us healthy, hydrated, clean and free of disease. Commercial plumbing is as important as the plumbing in your home, so next time you visit a commercial building, consider the care that went into designing and maintaining its vast systems.

Our technicians at 1-Tom-Plumber are trained and licensed professionals in residential and commercial plumbing.

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