Why deep east Denver basements often have one
Gravity takes waste from upstairs fixtures to the sewer lateral, which leaves the house at a certain depth. Fixtures lower than that, such as a bathroom in a very deep finished basement, can't drain by gravity. They drain into a sealed basin set in the floor, and a grinder or effluent pump pushes the waste up into the main line.
Rebuilt homes in Hilltop, Crestmoor and the Cherry Creek area often have lower levels deep enough to need one. Older homes that added a basement bathroom decades later may also have an ejector, sometimes installed without much attention to the lid seal or venting.
The basin is required to be sealed and vented to the outside, typically through the roof. That vent lets air move as the basin fills and empties. When any part of that sealed system leaks, sewer gas has a direct path into the room.
Parts worth knowing by name
- Basin
- The sealed tank in the floor, usually under a removable lid near the bathroom or mechanical room.
- Lid gasket
- The rubber seal between lid and basin rim. A dried, cracked or missing gasket is a frequent odor source.
- Vent pipe
- A pipe from the basin lid to the home's vent system. Without it, pressure changes push gas out through any weak seal.
- Discharge line
- The pipe carrying waste from the pump up to the main sewer line.
- Check valve
- A one-way valve on the discharge line that stops waste flowing back into the basin.
- High-water alarm
- A float-triggered alarm that sounds when the pump fails to keep up.
- Grommets
- Rubber seals where pipes and electrical cords pass through the lid. These dry out and loosen over time.
Signs that point to the ejector system
None of these proves it, but two or three together make the basin the first thing a plumber should check.
What to ask the plumber
- Is the basin vented, and does the vent tie into the main stack or go through the roof separately?
- What condition are the lid gasket and the cord and pipe grommets in?
- Is the check valve working, or is waste draining back after each cycle?
- Is the pump the right type for the fixtures connected to it?
- Does any repair need a permit from Denver, or from Glendale if the home is there?
- Should the basin be cleaned and the walls of the pit inspected while it's open?
Common questions
Can an air purifier handle ejector basin odor?
It may reduce the smell a little, but sewer gas from a failed seal will keep coming. Repair the seal or vent first.
How is an ejector different from a sump pump?
A sump handles groundwater from around the foundation. An ejector handles household wastewater. They should never be connected to each other.
General information for Hilltop, not a quote or professional advice. In an emergency, call 911.