Plumbing is one of the most essential systems in any home or commercial property. While many homeowners only notice plumbing when something goes wrong, understanding the rules behind proper pipe installation can save significant time, money, and stress. One of the most important guidelines in Minnesota plumbing is the 135 Rule in Plumbing Minnesota.
This rule, outlined in MN Rules Part 4714.0707, focuses on horizontal drainage piping and ensures that cleanouts are installed when the cumulative changes in pipe direction exceed 135 degrees. By following this rule, homeowners and plumbers can maintain a smooth, efficient plumbing system that minimizes clogs, backups, and emergency plumbing calls.
In simpler terms, the 135 Rule is designed to make your plumbing accessible and maintainable. Long sewer lines with multiple bends can easily become blocked if cleanouts are not installed in the right places. These cleanouts allow plumbers to inspect, clean, and repair the system without dismantling large sections of pipe.
Overview of the 135 Rule in Minnesota Plumbing
The 135 Rule in Minnesota is based on adaptations of the Uniform Plumbing Code. According to the MN Revisor’s Office (.gov), this rule requires that for every cumulative horizontal turn exceeding 135 degrees in a drain line, a cleanout must be installed.
For example:
- Three 45-degree turns in a line = 135 degrees → a cleanout is required.
- One 90-degree turn plus one 45-degree turn = 135 degrees → cleanout required.
Cleanouts are commonly installed at strategic points such as the base of vertical stacks, near foundation walls, or where the sewer line exits the property. These placements make future maintenance easier and prevent costly disruptions.
Additionally, the Minnesota plumbing code includes a 100-foot rule, which requires cleanouts for every 100 feet of developed horizontal pipe. This ensures accessibility along long runs of drainage, especially in residential plumbing systems or older homes with indirect sewer paths.
Key Purpose:
- Ensure smooth wastewater flow
- Allow easy access for clearing blockages
- Reduce the risk of sewer backups and pipe damage
Why the 135 Rule Matters?
The 135 Rule is not just a technical requirement; it has real, practical benefits for plumbing systems:
- Improved Wastewater Flow
Gradual bends in pipes allow wastewater to move smoothly, preventing turbulence that can trap debris. Compared to sharp 90-degree turns, 135-degree bends help maintain the momentum of waste flow, reducing clogs and pressure build-up. - Reduced Clogs and Backups
Improperly installed pipes with abrupt angles can accumulate waste quickly. This often leads to frequent backups, costly repairs, and the need for emergency plumbing services near me. By following the 135 Rule, plumbing systems remain free-flowing and require less intervention. - Better Venting and Air Balance
Properly angled pipes facilitate correct venting in Drain-Waste-Vent (DWV) systems, preventing gurgling sounds, sewer gas odors, and siphoning of traps. Good airflow ensures system longevity and minimizes maintenance calls. - Long-Term Pipe Durability
Pipes with gradual bends experience less stress at joints, reducing the risk of leaks, cracks, and premature failure. Homeowners benefit from residential plumbing that lasts longer without costly repairs.
How the 135 Rule Works in Practice?
Understanding the rule in practice is simple: plumbers and homeowners calculate the total horizontal angle of the drainage line. If the cumulative change exceeds 135 degrees, a cleanout is required.
Practical Examples
- A basement drain with three 45-degree bends → cleanout installed.
- A kitchen drain with one 90-degree turn plus one 45-degree turn → cleanout installed.
- Horizontal pipe under 5 feet with minor bends → may be exempt.
Cleanouts are typically installed in accessible locations, including:
- Sewer main exits
- Basement and crawlspaces
- Foundation walls or external plumbing access points
Additionally, the Minnesota plumbing code mandates that every 100 feet of horizontal drain line have a cleanout. This combination of directional and length requirements ensures that plumbing systems are easy to maintain and fully compliant with local codes.
Cleanout Requirements and Exceptions
While the 135 Rule provides clear guidance, there are exceptions homeowners and plumbers should know:
- Short Horizontal Runs
Pipes less than 5 feet in length (excluding sink or urinal lines) may not require cleanouts. These short runs are easy to clear manually or with basic plumbing tools. - Pipe Slope Considerations
Pipes with a slope of 72 degrees or less from vertical may also be exempt. Steeper slopes allow natural momentum for waste flow, reducing the need for cleanouts. - Older Homes and Long Runs
Homes with complex, indirect sewer layouts often require additional cleanouts, even if some sections are under 5 feet, to ensure access for maintenance. - Commercial Plumbing Applications
Large commercial plumbing systems with multiple bends often need strategic cleanout placement to prevent blockages and comply with safety codes.
By understanding these requirements and exceptions, homeowners can ensure their plumbing systems are both code-compliant and easy to maintain.
Benefits of Following the 135 Rule
Following the 135 Rule in Minnesota plumbing provides multiple advantages:
- Smooth Waste Flow: Minimizes turbulence and waste buildup.
- Fewer Clogs: Reduces emergency plumbing calls and costly repairs.
- Longer Pipe Life: Less stress on joints prevents leaks and cracks.
- Ease of Maintenance: Cleanouts make inspection and cleaning straightforward.
- Compliance with Local Codes: Ensures the system meets Minnesota plumbing standards.
Proper adherence to this rule benefits homeowners, property managers, and plumbers alike. It prevents common issues like slow drains, sewer odors, and frequent backups, while also improving overall plumbing efficiency.
Signs Your Plumbing May Not Follow the 135 Rule
Even if your plumbing looks fine, ignoring the 135 Rule can lead to subtle issues:
- Frequent clogs in specific areas
- Slow drainage or pooling water
- Gurgling sounds from drains
- Sewer odors inside or outside the home
- Pressure buildup or water hammer noises
If these signs are present, it may be time to consult a licensed plumber near me who understands Minnesota plumbing code requirements. Regular inspections can identify issues before they become costly problems.
How Plumbers Apply the 135 Rule in Minnesota?
Professional plumbers apply the 135 Rule during both installation and retrofitting:
- Residential Plumbing Systems
- New homes: cleanouts are installed according to cumulative pipe turns.
- Existing homes: retrofits ensure older pipes comply with MN Rules.
- Commercial Plumbing Systems
- Longer horizontal runs require multiple cleanouts.
- DWV systems, basement plumbing, and indirect sewer lines are carefully planned.
- Maintenance & Inspection
- Plumbers use cameras and diagnostic tools to locate bends exceeding 135 degrees.
- Corrective measures, such as installing additional cleanouts, ensure compliance and prevent blockages.
By following these practices, plumbers ensure that your system is efficient, safe, and fully compliant with local Minnesota regulations.
DIY vs Professional Installation
While minor drainage issues may be resolved by homeowners, the 135 Rule requires professional knowledge:
- DIY-friendly tasks: unclogging small sinks, basic maintenance, checking for slow drains.
- Professional tasks: installing cleanouts, inspecting long horizontal runs, ensuring proper slopes, and compliance with MN Rules Part 4714.0707.
Hiring a licensed plumber guarantees:
- Compliance with the 135 Rule in Plumbing Minnesota
- Correct cleanout placement
- Reduced risk of future emergency plumbing services
Maintenance Tips to Keep Your Plumbing 135-Rule Compliant
Maintaining your system according to the 135 Rule improves longevity and reduces plumbing emergencies:
- Regular Inspections: Schedule annual checks of sewer lines and cleanouts.
- Drain Cleaning: Clear drains every 6–12 months to prevent debris accumulation.
- Pipe Slope Checks: Ensure horizontal pipes maintain proper slope.
- Professional Assessment: Engage plumbers for periodic inspections and upgrades.
Checklist Table:
| Task | Frequency |
| Inspect exposed pipes & cleanouts | Annually |
| Clean drains & remove debris | Every 6 months |
| Check water flow & slope | Annually |
| Camera inspection of sewer lines | Every 2–3 years |
Conclusion
The 135 Rule in Plumbing Minnesota is an essential guideline for maintaining a safe, efficient, and long-lasting plumbing system. By requiring cleanouts for cumulative horizontal turns exceeding 135 degrees, the rule ensures proper access, prevents blockages, and promotes smooth wastewater flow.
Homeowners, property managers, and plumbers who understand and apply this rule benefit from fewer clogs, reduced maintenance, and compliance with Minnesota plumbing codes. Regular inspections, proper cleanout placement, and attention to horizontal pipe angles are critical for system longevity.
If you want professional, compliant, and efficient plumbing services in Minnesota, contact us today to follow the 135 Rule and other state-specific regulations. Properly maintained systems not only save money but also protect your property and ensure peace of mind.
FAQs
Q1: What is the 135 Rule in plumbing?
It requires cleanouts in horizontal drainage pipes when cumulative turns exceed 135 degrees.
Q2: Where is it applied?
In sewer mains, long horizontal runs, DWV systems, and basement plumbing lines.
Q3: How often should cleanouts be installed?
Every cumulative 135-degree turn and every 100 feet of horizontal drainage.
Q4: Can existing plumbing be updated to meet the rule?
Yes, licensed plumbers can install additional cleanouts and adjust pipe layouts.
Q5: Why hire a professional?
Ensures compliance with Minnesota code, smooth waste flow, and avoids costly emergency plumbing services.