Clogged Drain or Sewer Line Problem?

By the Westminster Emergency Plumber team · Updated September 2026

Count the Fixtures

This is the fastest way to work out what you have. If one sink, one tub or one toilet is slow and everything else in the house drains normally, the blockage is almost certainly in that fixture branch: a trap full of hair, grease in a kitchen line, or something that went down that should not have.

If two or more fixtures on different sides of the house are struggling at the same time, or if flushing a toilet makes water rise in a shower, the trouble is further downstream in the line that all of them share. Clearing one trap will not change that.

Watch the Lowest Drain

The lowest opening in a house is where a main line problem shows itself first, because that is where water comes back up when the pipe below cannot carry the flow. In most homes here that is the basement floor drain, sometimes a basement shower or laundry standpipe. If the floor drain fills up every time the washing machine empties, you have a main line problem, not a fixture problem.

Gurgling is another tell. Air being pulled through a trap because the line beyond it is partly blocked makes a sound you do not normally hear. A toilet that gurgles when the tub drains is describing the shared pipe underneath them.

Stop Adding Water

If a main line is blocked, everything you run into the system has to go somewhere, and the somewhere is usually your floor. Hold off on laundry and the dishwasher, keep showers short or skip them, and avoid repeatedly flushing a toilet that is not clearing. It is a small amount of inconvenience that prevents a much larger mess.

Skip the Chemical Drain Cleaner

These products rarely move a solid blockage, and they bring two real downsides. They leave caustic liquid sitting in the trap that a plumber has to open, and they can attack older cast-iron pipe, which a lot of homes here still have. If a drain has stopped entirely, stop using it and let it sit dry rather than pouring anything down it.

What Causes What

Fixture blockages have ordinary causes: hair and soap in a bathroom line, grease and food in a kitchen line, wipes that were sold as flushable and were not. They usually clear cleanly and stay clear for a long time.

Main line blockages have structural causes more often than not. Tree roots find the joints in older clay sewer tile and thicken there until nothing else gets past. Sections settle and form a low spot that collects solids. Cast iron scales up from the inside until the opening is a fraction of what it was. Those come back, and the interval between blockages tends to shorten.

When a Camera Run Is Worth It

For a first blockage, clearing it and seeing what happens is a reasonable approach. For a line that has blocked more than once, a camera inspection is the difference between paying to clear the same pipe indefinitely and knowing what is actually wrong with it. The footage shows the material, the condition and the location of the problem, and the line can be marked on the surface so any repair is planned rather than exploratory. Our sewer line repair page covers how that works.

If Sewage Comes Up Inside

Treat it as a health matter. Keep people and pets away from it, wear gloves if you have to move things out of the way, and do not run the furnace fan or an air handler that will push the air around the house. Do not try to force it down with a plunger or a chemical. Call and describe how far it has spread and which fixtures are involved.

Drains and Sewer Lines Around Westminster

Older streets in Westminster, Arvada and Northglenn were plumbed with clay sewer tile and cast-iron waste stacks, and both are now old enough to show it. Mature cottonwoods, silver maples and elms on those blocks have had decades to find a joint. Spring is the busy season, because snowmelt raises the groundwater that is already seeping into open joints, and roots start growing again at the same time. If you are on one of those streets, the local notes for Northglenn plumbing go into it further.

Arrange an Inspection

Tell Westminster Emergency Plumber how many fixtures are affected, whether the lowest drain is backing up and how many times this has happened before. Those three answers decide whether the visit starts at a trap or at the main cleanout. Read more about drain cleaning, see how a service call works or request a visit.