Signs Your Drain, Waste & Vent System Is Failing

Approximately half of U.S. multifamily apartment and condo communities are dealing with failing DWV systems. Why? Usually age.

A high percentage of housing stock was built at least 50 years ago, which is when most DWV piping reaches the end of its useful life.

Other reasons can be defect or environmental conditions that cause piping to fail prematurely.

If you’re noticing recurring leaks, strange odors, or slow drains throughout your building, you’re not alone—and these aren’t problems you can ignore.

Read on for signs that your building’s DWV system is in distress and may need to be replaced.

Leaks Behind Your Walls and Ceilings

When drainpipes corrode or are defective, they leak. That means wastewater (also called effluent) is dripping continuously behind your walls. Residents may hear the dripping before they see damp drywall or black mold. Once the damage is visible, the problem may already be affecting multiple units.

What to watch for:

Persistent moisture or water stains on walls and ceilings
Musty or other odors
Residents reporting sounds of dripping water when no fixtures are running

Sewer Gas Odor

When residents notice a persistent rotten-egg smell in hallways, units, or common areas, that’s sewer gas escaping through cracks in your vent pipes.

Your DWV system’s vent pipes are how the system “breaths.” Vents carry toxic sewer gases safely out of the building and regulate system air pressure so drains work properly. Since the gases are caustic, they eat away at the vent pipes causing fractures that leak fumes into the building.

Here’s the bigger problem: vent pipes typically fail at the same time as (or even before) your drainpipes. If you’re smelling sewer gas, your entire DWV system may be compromised.

What to watch for:

Sewage odors in hallways and other common areas
Multiple units or floors reporting the same issue

Chronic Slow Drains and Back-Ups

When residents across multiple units start reporting slow drains or back-ups, it’s not a coincidence, it’s a system-wide problem.

Over decades of use, waste material builds up on the interior walls of drainpipes, gradually narrowing the pipe diameter. This restricts flow throughout your building’s drainage network. Unlike a one-time clog from someone putting the wrong thing down a drain, this systemic narrowing can’t be fixed with plungers or drain snakes.

What to watch for:

Multiple units reporting slow drains and back-ups at the same time
Problems that affect the same areas repeatedly

Related Resources

SageWater Pipe-Smart Checklist

Use this diagnostic tool for a quick way to see if the troubles you’re experiencing in one of your building’s plumbing or mechanical systems indicate that it’s time for a repipe.

Download your Pipe-Smart Checklist now

SageWater Leak Log

Have your maintenance team use this incident tracker to record leak details and collect critical evidence. Review the log annually to inform budgeting and detect when to repipe one of your plumbing or mechanical systems.

Download your Leak Log now

See What DWV Pipes Are Made Of

Whatever material your DWV infrastructure was built with, it’ll last about 50 years so long as they aren’t defective, are well maintained, and environmental conditions are favorable.

Most older DWV systems and those in mid- and high-rise communities are made with cast iron or some other metal.

See why, and what other materials might be used when you need to replace your DWV system.

Drain, Waste and Vent Piping Materials