Quick answer
A sewer cleanout is a capped vertical pipe that gives access to the sewer line so it can be cleared or inspected with a camera. Look outside between the house and the street, along an exterior wall, or in a basement. If sewage is backing up, do not remove the cap yourself. The water can rise out of it and into your home.
What a sewer cleanout is
A cleanout is a vertical pipe connected to the underground sewer line, with a removable cap that gives access for maintenance, according to a fact card from the LRWRA, a wastewater authority that runs a cap-the-cleanout program. Roto-Rooter describes it as an access port for clearing obstructions in the sewer pipe, and says homeowners are responsible for the pipes within their property lines.
Its job is practical. Instead of working through a toilet or a roof vent, a plumber can reach the sewer line directly. Hart's Services, a plumbing company in the Tacoma area, says a cleanout lets a technician run a camera through the line to find the problem or clear a clog, and that without one, access can mean pulling a toilet or going through a roof vent, which costs more.
Where to find yours
Roto-Rooter says the most likely spot is outside, between the foundation and the street. It describes a 4-inch pipe with a screw cap, with a square knob or a recess on top. Other places it lists are the side of the home, near a bathroom, and less often inside a basement or wall. The LRWRA fact card says the cleanout is usually near the home and close to the property line. Hart's says many Tacoma homes have one in the basement, and that renovations, drywall or additions can hide an existing cleanout.
The City of San Jose offers more clues. It suggests looking along an exterior wall near a kitchen or bathroom, in line with where the water service enters the house, under a small concrete or metal cover marked sewer, or in a slight dip in the yard between the house and the street. San Jose notes that cities mark sewers differently, so these tips may not apply everywhere.
Old house plans, a previous owner, or the city's permit records can also help. The City of Tacoma suggests checking house plans, asking the previous owner and searching city permit records to locate the side sewer. If you cannot find a cleanout, Roto-Rooter says a plumber can often locate it or install one.
- Outside, between the house and the street
- Along an exterior wall near a bathroom or kitchen
- Under a small cover in the yard, sometimes marked sewer
- In the basement or garage, in some homes
- Behind a wall or hidden by landscaping or later additions
Why it matters in a backup
When a drain backs up, the first question is whether the problem is in your pipe or the public sewer. The City of Davis, California, explains how its staff use the cleanout. They check the main first, and if the property has a service cleanout that is not backed up, the blockage is most likely on the resident's side. If the cleanout is full, the problem is further downstream. Davis staff do this check as part of a service call, which is different from a homeowner opening the cap.
Responsibility depends on where you live, so check with your city or sewer district. The City of Tacoma says property owners maintain the side sewer from the building to the main, while the city maintains the main line. Riverside, California, puts the cleanout at the property line, where the homeowner's portion ends. Seattle Public Utilities says property owners are responsible for their side sewer, which often causes backups. If sewage comes up when you are not using water, Tacoma tells residents to call its sewer crew right away.
What not to do during a backup
Do not open the cleanout cap while sewage is backed up. Hart's warns that if the sewer is blocked and you remove a basement cleanout plug, the backed-up water and sewage can rise and flow into the home. A backed-up line is full, and opening the cleanout gives that water and sewage a place to escape. For an indoor cleanout, that place is your home. This is reasoning from how drains work, but it matches Hart's warning. Leave the cap on and let a plumber decide how to open it safely.
Seattle Public Utilities lists other steps that apply anywhere. It also says to wear long sleeves, rubber boots, gloves and eye protection for cleanup, and never to mix bleach and ammonia.
- Protect people first and turn off power to affected areas to avoid electrical hazards.
- Do not flush toilets or run water appliances.
- Do not try to stop sewage flowing from floor drains or other drains.
- Keep children and pets out of contaminated areas, and do not use electrical equipment while standing in water.
- Call a plumber, then call the utility if a main line blockage is suspected.
- Document the damage and keep cleanup invoices.
How a plumber uses the cleanout
With the cap off, a plumber can send a camera down the line to see roots, grease, debris or broken pipe, and can pass cable or water pressure through to clear a blockage. SPU says rooter services use water pressure or mechanical snakes, and suggests asking whether the cable is long enough to reach the city's main sewer.
SPU also points out that a camera cannot see through water. An inspection of a line that is still backed up will not show the blockage, so inspections are more useful after the line is cleared and drains again, when the pipe's condition can be assessed. That is a good reason to treat clearing and inspecting as two steps.
Call before digging or clearing near gas
Before clearing a blockage in a side sewer, SPU tells customers to call Puget Sound Energy to avoid damaging a gas line. The gas utility serving your area may have a similar request. Tacoma also suggests calling 811 for help locating lines. If you smell gas at any time, leave the building and call 911 or the gas utility.
Keep it capped and reachable
The LRWRA fact card explains why the cap matters. An intact cap keeps out rodents and small animals, blocks rainwater from entering the sewer, and keeps debris out of the line. Davis adds a practical note: a plumber is needed when the cleanout is blocked by landscaping or concrete or when no cleanout exists. Keep the area around yours clear, and avoid burying it under mulch, decks or planters.
When to call Pyper Plumbing
Call Pyper Plumbing for a sewer backup, for a drain that keeps clogging, or when you cannot find or reach a cleanout. Pyper provides sewer line repair, drain cleaning and emergency plumbing in Snohomish, Skagit, Whatcom and Island counties.
If sewage is coming up inside the house, stop using water, stay out of the affected area and call early. If you think the blockage is in the public main, such as sewage backing up when you are using no water, also contact your city or sewer district.
Common questions
Does every house have a sewer cleanout?
Not necessarily. Older homes may have none, and the rules differ by city. Roto-Rooter says a plumber can install a cleanout if the home lacks one, and Riverside, California, requires a cleanout at the property line.
Can I open the cleanout to see if the sewer is full?
It is risky during a backup. Hart's Services warns that removing the plug on a blocked line can let sewage rise and flow into the home. City crews and plumbers do this check with protective gear and a plan for the water.
Who is responsible for the cleanout and sewer line?
It varies. Tacoma and Seattle both say the property owner maintains the side sewer, while the city maintains the main. Riverside treats the property line cleanout as the dividing point. Ask your city or sewer district.
Can a camera find the problem during a backup?
Not well. Seattle Public Utilities notes that cameras cannot see through water, so inspections are more useful after the line has been cleared.
Sources
Facts in this guide come from the following references. Local rules and manufacturer instructions can differ, so follow your utility and your equipment manual.
- Cap the Cleanout fact card (LRWRA)
- Where is my sewer line cleanout located? (Roto-Rooter)
- What Is a Cleanout and Why Should You Have One? (Hart's Services)
- Clean-outs (City of San Jose)
- Sewer Backup Information (City of Davis)
- Home Sewer Line Maintenance brochure (City of Riverside)
- Wastewater Resources (City of Tacoma)
- Side Sewer Backups (Seattle Public Utilities)
- Troubleshooting Your Sewer Problem (Seattle Public Utilities)
- Sewage cleanup brochure (Seattle Public Utilities)
This guide is general information, not a substitute for an on-site inspection. If you smell natural gas, leave the building and call 911 or your gas utility. Pyper does not perform gas line work.
