What is the 135 Rule in Plumbing? A Complete Guide

When it comes to your home's plumbing, understanding key principles can save you from expensive repairs. One of these is the 135 rule in plumbing. Though it might sound technical, it's a crucial guideline that ensures your drainage system works efficiently and can be easily maintained.

The term "135 rule" can be confusing because it actually refers to three different concepts. It can relate to the length of your sewer line, the angle of your drain pipes, or the turns in a fixture's trap arm. Each has important implications for your home's plumbing health. In this guide, we'll break down each rule in simple language and explain why they matter.

The Three Meanings of the 135 Rule in Plumbing

The "135 rule" isn't a single, universal rule. Its meaning changes depending on the context. Below, we break down the three common applications of this important plumbing guideline.

1. The 135-Foot Sewer Main Rule

One critical interpretation of the 135 rule applies to the length of your home's sewer main. This guideline states that if your sewer line is longer than 135 feet, it must have a cleanout. A cleanout is an access point that allows a plumber to easily get their tools into the pipe to clear blockages.

Why 135 feet? Most standard plumbing snakes and hydro-jetting equipment can only reach about 100-135 feet into a pipe from a single access point. If your sewer line is longer than that without a cleanout, it becomes nearly impossible for a plumber to clear a clog in the middle of the line. Without this access, a simple clog can turn into a major problem, potentially requiring expensive excavation of your yard.

This rule is particularly important for homes set far back from the street, with long driveways, or on large properties. If you're buying a home, especially an older one, have a professional sewer scope inspection performed. A qualified plumber from a reputable company like The Waterworks can use a special camera to inspect your sewer line, identify its length, and determine if it has adequate cleanouts. This simple step can save you thousands of dollars.

2. The 135-Degree Horizontal Change Rule

The most common and officially codified meaning of the 135 rule relates to the change in direction of horizontal drainage pipes. Both the Uniform Plumbing Code (UPC) and the International Plumbing Code (IPC), the two major plumbing codes in the United States, have specific rules about this. The UPC, developed by the International Association of Plumbing and Mechanical Officials (IAPMO), states in Section 707.4:

"An additional cleanout shall be provided in a drainage line for each aggregate horizontal change of direction exceeding 135 degrees (2.36 rad)."

In simple terms, if your drain pipes bend and turn too much, you need to add an extra cleanout. Imagine your drainpipe as a road. Too many sharp turns make it difficult for waste and water to flow smoothly. It also makes it harder for a plumber's snake to navigate the pipe to clear a clog. The 135-degree rule ensures there are enough access points to properly maintain the system.

To put it in perspective, a standard 90-degree elbow is a very sharp turn. Two of these in a row create a 180-degree change in direction, which requires a cleanout. However, if a plumber uses two 45-degree fittings to make a more gradual 90-degree turn, the change is less abrupt and less likely to cause blockages. The code allows for a total of 135 degrees of turns before a cleanout is required.

3. The 135-Degree Trap Arm Rule

The third application of the 135 rule is found in the context of a fixture's trap arm. The trap arm is the section of pipe between the P-trap (the U-shaped pipe under your sink) and the vent. This part of your drainage system prevents sewer gases from entering your home. The UPC has a specific rule for the trap arm, particularly for larger pipes. UPC Section 1002.3 states:

"For trap arms, 3 inches (80 mm) in diameter and larger, the change of direction shall not exceed 135 degrees (2.36 rad) without the use of a cleanout."

This rule is similar to the horizontal change rule, but it applies specifically to the trap arm. Just like with main drain lines, too many sharp turns in the trap arm make it difficult to clear clogs. While this is more technical, it's good for homeowners to be aware of. It highlights the level of detail that goes into designing a safe and effective plumbing system.

Understanding Cleanouts: Your Plumbing System's Best Friend

Now that we've established that two of the three 135 rules are about cleanouts, let's talk about what they are and why they're so important. A cleanout is a capped pipe that provides direct access to your drainage system. You can usually find them in your basement, crawlspace, or outside in your yard near your home's foundation. They look like a Y- or T-shaped fitting with a screw-on cap.

Think of a cleanout as a service door for your plumbing. When a drain clogs, a plumber can simply unscrew the cap, insert a camera to diagnose the problem, and then use a plumbing snake or hydro-jetter to clear the blockage. Without a cleanout, the process is much more complicated. A plumber might have to remove a toilet, climb on the roof to access a vent pipe, or excavate your yard to get to the main sewer line.

Why Cleanouts are Essential

For homeowners, the presence of adequate cleanouts is a matter of convenience, cost, and peace of mind. Here's why you should care about them:

They Save You Money: A simple drain cleaning service is far cheaper than excavating your property to access a buried pipe. By ensuring your plumbing system has the required cleanouts, you're making future maintenance and repairs much more affordable.

They Prevent Major Disasters: A clogged sewer line can cause raw sewage to back up into your home through your toilets, showers, and sinks. This is not only a disgusting mess but also a serious health hazard. Cleanouts allow for quick and effective clearing of clogs before they turn into a full-blown backup.

They Protect Your Property: Excavating a sewer line can damage your landscaping, driveway, or even your home's foundation. Properly placed cleanouts eliminate the need for this destructive work.

Plumbing Code Requirements for Cleanouts

To ensure that every home's drainage system is serviceable, both the Uniform Plumbing Code (UPC) and the International Plumbing Code (IPC) have strict requirements for cleanout placement. The International Code Council (ICC) publishes the IPC, which is widely used across the United States. [5]

Here is a table that compares the key cleanout requirements of the UPC and the IPC:

Feature	Uniform Plumbing Code (UPC)	International Plumbing Code (IPC)
Horizontal Change of Direction	Cleanout required for aggregate changes exceeding 135 degrees.	Cleanout required for each change of direction greater than 45 degrees.
Pipe Run Length	Cleanout required for every 100 feet of horizontal pipe.	Cleanout required for every 100 feet of horizontal pipe.
Upper Terminal	Cleanout required at the upper end of each horizontal drain line.	Not explicitly required, but good practice.
Building Drain/Sewer Connection	Two-way cleanout often required near the connection.	Cleanout required at or near the junction.

As you can see, the IPC is generally stricter when it comes to changes of direction. However, both codes emphasize the same core principle: your drainage system must be accessible for maintenance and repair. A professional plumber will be familiar with the specific code requirements in your area and can ensure your home is compliant.

Practical Applications for Homeowners

Understanding the 135 rule and the importance of cleanouts isn't just for plumbers. As a homeowner, this knowledge can empower you to make smart decisions that protect your property and your wallet.

When Buying a Home

If you're in the market for a new home, especially an older one, the 135 rule should be on your checklist. During the home inspection process, specifically request a sewer scope inspection. This is a service where a plumber feeds a small camera into the sewer line to inspect its condition.

The inspector can determine if the sewer line is longer than 135 feet and if it has the necessary cleanouts. The camera can identify cracks, breaks, tree root intrusion, or other signs of damage that could lead to future problems. The inspector can also verify that the home's drainage system complies with local plumbing codes.

If the inspection reveals that the home has a long sewer line without a cleanout, or if there are other plumbing issues, you can use this information to negotiate with the seller. You could ask them to install a cleanout before closing, or request a credit to cover the cost.

During Renovations

If you're planning a home renovation, it's the perfect time to address any shortcomings in your plumbing system. As you open up walls and floors, you have a unique opportunity to add cleanouts where they're needed.

For example, if you're reconfiguring your kitchen layout and the new sink will be further from the main drain line, you may need to add a cleanout to comply with the 135-degree rule. Or, if you're finishing your basement and notice there's no cleanout on the main building drain, you should have one installed while the area is already under construction.

For Routine Maintenance

Even if you're not buying a new home or renovating, understanding the 135 rule can help with routine maintenance. Knowing where your cleanouts are located is the first step. If you don't know where they are, a professional plumber can help you locate them. Once you know where they are, keep the area around them clear and accessible.

If you ever experience a slow drain or a minor clog, you can tell your plumber where the nearest cleanout is, which will help them resolve the issue more quickly. For major clogs or any work on the main sewer line, it's always best to call a professional from a trusted company like The Waterworks.

Common Problems Caused by a Lack of Cleanouts

Ignoring the 135 rule and the need for proper cleanouts can lead to problems ranging from minor annoyances to major catastrophes. Here are some of the most common problems homeowners face when their drainage system lacks adequate cleanouts:

Ineffective Clog Removal

Without a direct access point, clearing a clog becomes a guessing game. A plumber may have to try multiple methods and access points to reach the blockage. They might have to remove a toilet to access the main drain, or go up on the roof to run a snake down a vent pipe. These methods are less effective than going through a cleanout and may not fully clear the clog.

Increased Costs

The extra time and effort required to clear a clog without a cleanout translates to higher costs for the homeowner. A simple service call can turn into a multi-hour project. Furthermore, if the clog is severe and cannot be cleared through conventional methods, the only remaining option is often excavation. Digging up a sewer line is a major undertaking that can cost thousands of dollars.

Property Damage

When a clog cannot be cleared in a timely manner, it can lead to a sewer backup. This is when raw sewage from the main sewer line backs up into your home through your drains. A sewer backup can cause extensive damage to your floors, walls, furniture, and personal belongings. The cleanup process is not only expensive but also a serious health hazard.

Tree Root Intrusion

Tree roots are naturally drawn to the moisture and nutrients in your sewer line. They can infiltrate the pipe through tiny cracks or loose joints and grow into a dense mat that completely blocks the flow of waste. Removing tree roots from a sewer line requires a powerful cutting tool. Without a cleanout, it can be very difficult to get the tool to the location of the roots and effectively clear them out.

When to Install Additional Cleanouts

While plumbing codes set the minimum requirements for cleanouts, there are situations where it makes sense to install additional cleanouts for even better access. Here are some scenarios where you should consider installing additional cleanouts:

Long Pipe Runs

Even if your sewer line is less than 135 feet long, if you have a particularly long, straight run of pipe, it can be beneficial to have a cleanout in the middle. The UPC requires a cleanout every 100 feet, but an intermediate cleanout can still make it easier for a plumber to service the line.

Numerous Bends

If your drain lines have a lot of bends and turns, even if they don't exceed the 135-degree rule, it can be a good idea to add extra cleanouts. Bends are where clogs are most likely to occur, so having a cleanout near a series of bends can make it much easier to clear any blockages.

Before a Problem Occurs

The best time to install a cleanout is before you have a problem. If you live in an older home that was built before modern plumbing codes were in effect, there's a good chance that your drainage system isn't adequately equipped with cleanouts. Have your plumbing system inspected by a qualified professional. They can identify any areas where cleanouts are needed and install them for you.

Frequently Asked Questions (FAQ)

Q: Is the 135 rule a law?

A: The 135 rule is a guideline that is codified in the major plumbing codes, such as the Uniform Plumbing Code (UPC) and the International Plumbing Code (IPC). These codes are often adopted by local jurisdictions and become law in those areas. A licensed plumber will be familiar with the specific codes in your area.

Q: How do I know if my house has enough cleanouts?

A: The best way to know for sure is to have your plumbing system inspected by a qualified plumber. They can locate your existing cleanouts and determine if you need any additional ones based on the layout of your pipes and the requirements of your local plumbing code.

Q: Can I install a cleanout myself?

A: While it may be tempting to save money by installing a cleanout yourself, it's a job best left to a professional. Installing a cleanout requires cutting into your main drain line, which can be dangerous and messy if not done correctly. A professional plumber has the tools, knowledge, and experience to do the job safely.

Q: How much does it cost to install a cleanout?

A: The cost of installing a cleanout can vary depending on factors such as the location of the pipe, the type of pipe, and the accessibility of the area. However, the cost of installing a cleanout is almost always significantly less than the cost of excavating a sewer line to clear a clog.

Q: What should I do if I have a clog and no cleanout?

A: If you have a clog and no cleanout, your first step should be to call a professional plumber. They have the tools and expertise to clear the clog, even without a cleanout. Once the clog is cleared, you should seriously consider having a cleanout installed to prevent future problems.

Conclusion: A Small Rule with a Big Impact

The 135 rule in plumbing, in all its forms, is a testament to the thoughtful engineering that goes into a modern plumbing system. Whether it's ensuring a sewer line is serviceable, preventing clogs in drain lines, or making sure a trap arm functions correctly, this simple guideline plays a crucial role in the health and longevity of your home's plumbing.

As a homeowner, you don't need to be a plumbing expert, but understanding the principles behind the 135 rule can empower you to make smarter decisions, prevent costly repairs, and maintain a safe and healthy home. By ensuring your home has the proper cleanouts and that your drainage system is compliant with local codes, you're making a wise investment in your property.

If you have any questions or concerns about your home's plumbing, don't hesitate to reach out to a trusted professional. A qualified plumber can provide you with the expert advice and service you need to keep your plumbing system flowing smoothly for years to come.

References

1.International Association of Plumbing and Mechanical Officials (IAPMO). (2017). Code Spotlight: 707.0 Cleanouts. IAPMO.

2.International Association of Plumbing and Mechanical Officials (IAPMO). (n.d.). 1002.0 Traps Protected by Vent Pipes. Uniform Plumbing Code.

3.Allied Reddi-Rooter. (n.d.). Buying a home? Learn about the sewer main 135 rule cleanout before you make that offer.

4.PHC Pros. (2014). Code requirements for drainage system cleanouts.

5.International Code Council (ICC). (n.d.). International Plumbing Code (IPC).