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Drains and sewer · Apartments, HOAs and condos

Drains Backing Up in More Than One Apartment Unit

When showers, tubs and kitchen sinks back up in several units, the shared stack or building line is blocked. How we clear it, camera it and plan a lasting fix.

Short answer

When more than one unit backs up, the blockage is in the shared stack or the building's main line, not in the units. We clear it by cable or jetter from the nearest cleanout, camera the line to find the cause, and give the property manager a written proposal for any repair.

What was wrong

The office phone starts ringing. A ground-floor tenant has water coming up in the shower. The unit next door has a kitchen sink that won't drain. Someone upstairs says the tub is gurgling. Three calls in an hour from different units is not three plumbing problems. It's one.

In an apartment building, units on the same stack or the same branch of the building line share a drain. When that drain is blocked, the lowest fixtures overflow first, which is why ground-floor tubs and showers are usually where it shows. Kitchen lines add grease over time, and flushed wipes and paper add up in the main line.

How we find the cause

We map the pattern before we cut anything. Which units, which fixtures, which floors, and what was running when it happened. That tells us whether we're looking at one stack or the whole building line.

Then we go to the cleanout and cable or jet the line. When the water drains freely, we camera the line to see why it blocked. The camera shows whether the cause is buildup that needs scheduled cleaning, roots, a sag that holds debris, or a damaged joint. In buildings with repeat problems, what the camera shows is the most valuable finding, because it turns a recurring emergency into a plan.

If there's no cleanout where we need one, we say so, because adding one often makes every future call easier.

What fixes it

We clear the line first so tenants can use their plumbing again. For heavy grease or scale, jetting cleans the pipe wall and not only a path through it.

If the camera finds damage or a design problem, we write a proposal and the property manager or owner approves it before work starts. For buildings that back up on a pattern, we can talk about a cleaning schedule matched to what the camera showed. We stop the symptom first, then plan the larger fix.

What to know before you call

Give us a list of affected units, the tenants' contact details and any access requirements like gate codes or lockboxes. Tell us what notice tenants have had. If sewage reached the floor in any unit, that unit needs to be cleaned and sanitized, and the tenant should stay out of the wet area. Sewage is a health issue. Mention whether you have insurance or a management company that needs to approve the work, and who is authorizing it.

Ask your owner or management company where the building's cleanouts are, and whether the sewer between the building and the city main is yours or the city's. The boundary differs by city.

If you live in a condo or townhome

If your drain and your neighbors' drains are all slow, the shared line is blocked. Contact your HOA or management company first. They are usually responsible for the shared line, and what our camera shows can help you show them what's wrong.

Last reviewed 2026-10-05. This page describes a pattern we see on service calls; your building, fixtures and city rules decide the details.

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