The 135 rule comes from the Uniform Plumbing Code. When the horizontal turns in a drain line add up to more than 135 degrees, that line needs one more cleanout. The International Plumbing Code uses a 45 degree trigger instead. A plumber who explains both on a page owns a question nobody else answers well.
What Changed
- UPC 707.4 calls for an extra cleanout for each aggregate horizontal change in direction past 135 degrees, on top of the upper terminal and every 100 feet.
- Three 45 degree bends add to 135 and do not trip the rule. A 90 and a 45 plus one more bend do.
- Where the IPC is the code, any turn over 45 degrees gets a cleanout, but one cleanout covers every 40 feet of pipe.
- In Google Ads data Clickflame pulled in October 2026, sewer cleanout drew about 6,600 U.S. searches a month at a suggested bid near $44.94.
- The question itself is too small for Google Ads to report, and the written answers on page one are a 2013 slope article and forum threads.
Code text updated October 2026
Two Codes, Two Numbers
A Uniform Plumbing Code city and an International Plumbing Code city can look at the same drain line and ask for different cleanouts. Under the UPC, you add up the horizontal turns and add a cleanout once the total passes 135 degrees. Under the IPC, any single turn sharper than 45 degrees calls for one, and one cleanout covers 40 feet of pipe.
That is the whole 135 rule. It sounds small. It decides where a cleanout goes on a remodel, whether an inspector signs off, and how hard the next stoppage is to clear.
The person who types this question is often a homeowner with an open floor, a remodeler planning a drain run, or a new apprentice. Every one of them is close to a job a plumber gets paid for. A page that gives the clean answer, in plain words, wins that person before they ever call.
What the Code Actually Says
The rule lives in section 707.4 of the UPC. The 2025 California Plumbing Code, in effect since January 1, 2026, carries the same wording. Each horizontal drainage pipe gets a cleanout at its upper terminal. Runs over 100 feet get one for each 100 feet. Then comes the line people search for. An additional cleanout goes in a drainage line for each aggregate horizontal change in direction exceeding 135 degrees.
Minnesota adopts the UPC with its own amendments, and its rule keeps the same 135 degree sentence in Minnesota Rules 4714.0707. It also adds a cleanout above the fixture fitting for every urinal. That is a good reminder that the model code is a starting point. The city's adopted version is the one the inspector reads.
The key word is aggregate. The rule is not about any one fitting. It is about the total. Walk the line from the cleanout and add each horizontal bend as you go. When the running total goes past 135, the count starts over at a new cleanout.
How to Count the Turns
Most mix ups come from the math. The table counts the runs a plumber sees most, the way the UPC text reads.
| Bends in the run | Total | Extra cleanout under UPC 707.4? |
|---|---|---|
| One 90 | 90 degrees | No |
| Two 45s | 90 degrees | No |
| Three 45s | 135 degrees | No, it must exceed 135 |
| A 90 and a 45 | 135 degrees | No, it must exceed 135 |
| A 90 and two 45s | 180 degrees | Yes |
| Two 90s | 180 degrees | Yes |
| Four 22.5s and a 90 | 180 degrees | Yes |
Take a worked example. A kitchen remodel moves the sink to an island. The new drain leaves the old line with a 45, swings around a footing with another 45, and then turns 90 into the island. That adds to 180 degrees. Under the UPC, that run needs a cleanout before the total passes 135, so a plumber would plan one after the second 45.
The UPC also lists times a cleanout can be left off. A horizontal drain shorter than 5 feet can skip one unless it serves sinks or urinals. A pipe sloped at 72 degrees or less from vertical, a one fifth bend, can skip one. Pipe above the lowest floor needs none, except the building drain, its horizontal branches, kitchen sinks and urinals. And an approved two way cleanout near where the building drain meets the sewer can stand in for the upper terminal cleanout. All four exceptions sit in the same section 707.4.
How the IPC Handles the Same Line
Plenty of searchers live under the other code. Michigan's rule, built on the IPC, says cleanouts go at each change of direction greater than 45 degrees in the building sewer, building drain and horizontal waste or soil lines. Where a run has more than one change, one cleanout covers each 40 feet of developed length. Horizontal drains and building sewers also get cleanouts no more than 100 feet apart.
So the same island sink run reads two ways. In a UPC city, the plumber counts degrees. In an IPC city, the plumber counts feet between turns. A page that shows both, side by side, answers the person no matter which state they live in.
Ron George, a former chair of the International Residential Plumbing and Mechanical Code Committee, laid the two codes side by side in PHCP Pros in 2014. His piece covers the 2012 IPC and the 2009 UPC, so section numbers have moved since. The ideas still hold. Under the UPC, trap arms can change direction up to 90 degrees without a cleanout, and trap arms 3 inches and larger can go to 135 degrees. Cleanouts need room to work, too. The UPC asks for 12 inches in front of cleanouts on 2 inch and smaller pipe and 18 inches on larger pipe. The IPC asks for 18 inches on pipe up to 6 inches and 36 inches on 8 inch and larger pipe.
Why the Answer Turns Into a Job
Nobody searches the 135 rule for fun. A homeowner asks it because a line under the slab keeps backing up and the drain cleaner could not get a cable through. A remodeler asks because the inspection is next week. An apprentice asks because the foreman used the phrase. Each of those people is a step away from a cleanout install, a camera inspection or a drain cleaning call.
The money is in the searches around it. In Google Ads data Clickflame pulled in October 2026, sewer cleanout drew about 6,600 U.S. searches a month with a suggested bid near $44.94 a click. Plumbing cleanout drew about 1,900 at near $32.60. Main line cleanout drew about 320 at near $73.19. Install sewer cleanout drew about 480 at near $10.31.
Drain cleaning near me is the big one. In that same pull it averaged about 110,000 searches a month, swung to about 246,000 in September 2026, and carried a suggested bid near $44.22. A plumber who explains cleanouts well on the site earns trust from the same homeowner who later searches for drain cleaning.
The 135 question itself is too small for Google Ads to give a number. That is fine. It is a trust question. In October 2026 the Google results for it showed an AI answer, short videos, a 2013 article about pipe slope, a Reddit thread and a Facebook group post. Not one written page from a plumbing company answered it head on. Small companies win questions like that with a clear page, not with links.
Put the Answer on Your Site
A plumbing company can own this answer with one page. Keep it short, clear and local.
- Say the rule in the first two sentences. Add the horizontal turns, and past 135 degrees the line needs another cleanout.
- Name your code. Say which code your city or county uses, UPC or IPC, and which edition. A line like that shows you work there.
- Show the counting table. Copy the idea of the table above with the fittings your crews use most.
- Add one real photo. A cleanout your tech installed, with the address left out. Real work beats a stock picture.
- Explain what happens without one. A clog past a long run of bends is harder and slower to clear. Say how your crew handles that job.
- Answer the follow up questions. Use the questions at the bottom of this page, written the way people ask them.
- Link it to the money pages. Point it at your drain cleaning, sewer camera and cleanout install pages, and make the phone number tap to call.
Run the page through the free schema generator to add Article markup. Then link it from your Business Profile posts. The plumber lead generation guide covers where the rest of the calls come from.
Answer It on the Phone Too
When a caller asks about the 135 rule, they usually have a reason. Ask four things before you quote.
- Is this new work, a remodel, or an old line that keeps clogging?
- Where is the nearest cleanout today, inside or outside?
- Has anyone run a camera down the line?
- Is an inspection already on the calendar?
Then book the visit. A remodeler with an inspection date does not wait for a call back. A missed call goes to the next plumber on the map, and the free missed call calculator shows what that costs in a minute.
Clickflame builds pages like this for trade businesses, one real customer question at a time, each tied to a tracked phone line so the owner can see which answers book jobs.
Evidence
Every number in this story comes from one of these. If a figure is ours, the paragraph says so.
- California Plumbing Code 2025 (Title 24, Part 5), section 707.4 Location, via Codebook
- Minnesota Rules 4714.0707, Cleanouts (UPC 707.4 as amended), Office of the Revisor of Statutes
- Michigan Admin. Code R. 408.30757, Horizontal drains within building and building sewers, via Cornell Legal Information Institute
- Ron George, Code requirements for drainage system cleanouts, PHCP Pros (March 14, 2014)
- Cover photo, Sewer cleanout, Amherstburg, Ontario, by Chris Woodrich, CC BY-SA 4.0, via Wikimedia Commons
Clickflame builds the websites and runs the local search and ads for service businesses that live on the phone ringing. See websites built for plumbers, look at the work, or pick a time and we will look at your numbers with you.
Help Desk Answers
What is the 135 rule in plumbing?
It is a cleanout rule in the Uniform Plumbing Code, section 707.4. Add up every horizontal change in direction on a drain line. Once the total goes past 135 degrees, the line needs one more cleanout. The California code that took effect January 1, 2026 carries the same words.
Do three 45 degree fittings need a cleanout?
Not under the 135 rule alone. Three 45s add up to exactly 135 degrees, and the code says exceeding 135. A fourth 45, or a 90 plus a 45 and anything more, pushes the total past the line. The line still needs its upper terminal cleanout and one every 100 feet.
Does the IPC have a 135 rule?
No. The International Plumbing Code puts a cleanout at each change of direction greater than 45 degrees in building sewers, building drains and horizontal waste or soil lines. Where a run has more than one change, one cleanout is enough for each 40 feet of developed length.
Do vertical turns count toward 135 degrees?
The UPC text says horizontal change in direction, so the count is about turns in the horizontal plane. Your local inspector reads the adopted code for your city, and local amendments can change details. Ask before you cover the pipe.
How much room does a cleanout need in front of it?
Under the UPC as quoted by PHCP Pros, 12 inches for pipes 2 inches or smaller and 18 inches for larger pipe. Under the IPC it is 18 inches for pipe 6 inches and smaller and 36 inches for 8 inches and larger. Check the edition your city adopted.
Can a two way cleanout replace the upper terminal cleanout?
Yes, under UPC 707.4. An approved two way cleanout fitting inside the building wall near the building drain and sewer connection, or outside at the lower end of the building drain and extended to grade, can take the place of the upper terminal cleanout.
