Keep grease and wipes out of the drain, flush only toilet paper, keep trees and large shrubs away from the line and cleanout, act on slow drains early, and get a camera look at older lines. Grease, debris and roots cause nearly all reported sewer blockages.
What actually blocks sewer lines
The EPA's report to Congress on sewer overflows breaks down the causes of reported blockage events:
| Cause | Share of blockage events |
|---|---|
| Grease | 47% |
| Grit, rock and other debris | 27% |
| Roots | 22% |
| Roots and grease together | 4% |
These figures are for blockages in public sewer systems reported to the EPA, not for house drains, but the causes carry over. All four categories are things a household can affect. The City of Phoenix says the same about its own lines. Coagulated grease and cooking oil are the biggest problem, and roots from trees and invasive shrubs such as oleanders are second. Phoenix also cleans on a schedule: about 25 to 30 percent of its more than 5,000 miles of sewer, over 1,200 miles, each year. The city inspects with a camera first, then cleans where the camera finds trouble. Your private line gets no such program, because the city does not inspect home sewer lines. Maintenance is yours to do.
Kitchen and bathroom habits
Handle grease the way Phoenix asks. Let cooking grease or oil cool in the pan, then scrape it into the trash. Warm grease looks like a liquid, but the city says it cools and coagulates in the line, "in much the same way cholesterol blocks arteries." Hot water does not fix it, since the grease cools further down the pipe. The city's slogan is "Cease the Grease."
Flush only toilet paper. Phoenix says wipes, paper towels and cotton products do not break down in transit, regardless of what the package claims. Feminine products and too much toilet paper cause clogs too. A wipe that leaves your toilet has not gone away, it has gone downstream to catch on a root or a rough joint.
Keep debris out. The EPA's second-largest category is grit, rock and other debris. In a house that means food scraps, coffee grounds, and anything that settles. A drain strainer in kitchen sinks and showers helps catch it before it reaches the line. See what not to put down the drain for the full list.
Roots and landscaping
Phoenix advises against planting a tree or large shrub near your property line, over or near the sewer line, or near the cleanout. Roots are drawn to the water vapor that leaks from cracks and loose joints, and once inside a pipe they form a root ball that traps everything else. If big plants are already there, see signs of tree roots in a sewer line and whether hydro jetting keeps roots from coming back.
Know your cleanout. It is the capped pipe that gives a plumber access to your line. Phoenix notes that private cleanouts are on your property and outside city jurisdiction. Find it, keep it clear of mulch, pavers and plants, and read what a sewer cleanout is. If you can't find one, that is worth knowing before a backup, not during.
Warning signs and camera checks
Phoenix tells residents to watch for reduced drain flow and to have a plumber inspect if a blockage is suspected. Several drains slowing at once, gurgling, or a toilet that bubbles when you run the washer all point at the main line rather than one fixture. Our guide to signs of a sewer backup covers the full list.
### When to run a camera
The city checks its sewers by camera before it cleans them, and you can do the same. A camera shows the pipe material, the joints, and whether roots are getting in. Consider a camera look in these cases:
- After a backup or a cleaning, to see whether the cleaning fixed the cause or only cleared it for now.
- When you buy a house. See should you get a sewer scope before buying.
- On an older line, even without symptoms. San Luis Obispo lists clay at 50 to 60 years and cast iron at 30 to 50, so an older house is worth a look.
If it does need cleaning, hydro jetting scours the full pipe wall. If the camera shows a failing pipe, see full reline, partial reline or nothing and tree roots: repair or replace.
### Where the trouble is, by symptom
| What you notice | Likely location | First move |
|---|---|---|
| One sink or tub drains slowly | That fixture or its branch drain | Clear that drain; see how to fix a slow-draining sink |
| Every drain slow, or gurgling in more than one | Main sewer line | Camera the line before it becomes a backup |
| Toilet bubbles or water rises in a tub when the washer drains | Main sewer line | Stop using water and call a plumber |
| Sewage in the lowest tub or floor drain | Main sewer line, usually blocked | Stop using water; open the cleanout only if you know how |
| Manhole overflowing in the street or easement | City line | Call Phoenix Water Services |
Because the main line serves the whole house, the lowest drain shows trouble first. That is why a backup so often shows up in a downstairs shower or a floor drain before anywhere else.
### Two examples of how to act
These are made-up examples to show the thinking, not real jobs.
A slow kitchen drain, once. Only the kitchen sink is slow, and it has been a week since you poured off a pan of bacon grease. Clear the trap and drain, start scraping grease into the trash, and watch it. A single slow fixture is rarely a sewer problem.
Slow drains, twice in a year. The shower and a bathroom sink both slow down, then the toilet gurgles when the washer runs. That points at the main line. Book a camera look now, while it is a maintenance call and not a flooded floor, and find out whether the cause is grease, debris, or roots.
### A simple yearly routine
- 1Scrape grease into the trash all year, and check that nobody in the house is flushing wipes.
- 2Walk the yard and find the cleanout. Keep it clear.
- 3Look at what has grown near the line since last year.
- 4Run water in every drain, including the ones nobody uses.
- 5Note any slow drain and act on it, rather than waiting for a backup.
Before monsoon season, and who owns the line
Heavy rain finds weak spots in old lines, and the EPA lists sewer defects that let stormwater and groundwater in among the causes of overflows. Read how to prevent a sewer backup before monsoon and ask about a backwater valve if your property is low.
You own the line out to the city main, and Phoenix does not inspect private laterals. The one exception is a broken pipe in the public right-of-way at a single-family or duplex home. See who is responsible for the sewer line in Phoenix. If a manhole is overflowing in the street, that is the city's line: Phoenix Water Services takes calls at 602-262-6691 during business hours and 602-261-8000 after hours.
HQ Plumbing offers free estimates, 24/7 emergency service and upfront pricing when a backup will not wait.