Ontario Municipal Utilities Company manages the City's gravity sewer lines and the Inland Empire Utilities Agency treats the wastewater, so a clog between your fixtures and the public main is yours to clear. Call the number on this page to be connected with a local plumber in Ontario.

Is the clog mine or the City's?
Ontario Municipal Utilities Company (OMUC), the City-owned utility, manages the gravity sewer lines under Ontario streets, and the City's wastewater goes to the Inland Empire Utilities Agency for treatment. A blockage in one of those public mains usually shows up on several properties at once. If only your house is affected, the clog is almost always in your own piping: a fixture trap, a branch line, or the main drain running from the house out to the street. That private section is where a plumber works. For a suspected problem in the street, OMUC customer service is (909) 395-2050.
Do older Ontario homes clog more often?
Ontario started in 1881 as the Chaffey brothers' irrigated "model colony," and its housing spans well over a century. The citywide median home was built in 1980, which means a large share of houses are old enough to have cast iron inside the walls or older pipe in the yard. Those materials can scale and corrode on the inside and let roots in at joints, so clogs return faster. Newer neighborhoods such as Ontario Ranch usually have plastic drain pipe, where clogs come mostly from grease, wipes and hair rather than the pipe itself.
When should I ask for jetting or a camera?
A cable clears most single blockages. If the same line backs up again within a few months, ask about a camera inspection to see what is catching debris, then hydro jetting if the pipe is sound and coated with grease or root growth. In a household with heavy cooking, the kitchen line is the usual candidate. Ask the plumber to explain what the camera shows before agreeing to any repair, since a sag or crack in the private line is the owner's to fix.
A local note
Ontario's Building Department takes permit applications electronically through the City's Citizen Portal. Routine clog clearing does not usually involve a permit, but replacing a section of sewer pipe is construction work, so if a camera finds damage, have your plumber confirm what the City requires before digging. Ontario also tests backflow assemblies under its cross connection control rules, which applies to some irrigation and commercial setups rather than to ordinary drains.
Drain Cleaning questions in Ontario
How can I tell whether a clog is in one fixture or in the main line?
Do older homes here have more drain trouble than newer ones?
Do I need a permit to have a drain cleared?
Why does a drain smell even when it empties fine?
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