Short definition
An up-flush system is a packaged tank-and-macerator-pump unit installed behind a toilet (or in a small adjacent enclosure) that lets a basement bath drain up to the gravity drain above instead of needing a sealed in-floor sewage-ejector basin. When the toilet flushes, waste enters the unit’s tank; the macerator grinds solids and pumps the slurry through small-bore (¾”–1″) tubing to the gravity drain. The defining advantage: no slab demolition required.
What it is
The packaged unit sits behind the toilet (or, on multi-fixture models, in a small enclosure adjacent to the bath). A standard-looking toilet bowl drains horizontally into the unit’s tank. A macerator with cutter blades grinds the waste; an integrated pump then lifts the slurry through small-diameter discharge tubing — typically ¾ inch to 1¼ inch — up to the gravity drain or stack above.
Common products in this category:
- Saniflo — Saniflo Up, Saniflo Sanibest, Saniflo Sanigrind. Saniflo Up handles toilet only; Sanibest can serve a full bath group.
- Zoeller Qwik-Jon Ultima.
- Liberty Pumps Ascent II.
Hardware retail runs $1,200–$2,500; installed cost is usually $2,500–$5,000, well below the $5,000–$10,000 range for opening a slab and installing a sealed sewage-ejector basin.
Why it matters to a homeowner
In a Seattle, Tacoma, or Bellingham daylight-basement home where the basement floor sits at or below the building drain, adding a bathroom usually means one of two systems: a sealed sewage-ejector basin (full demolition: cut the slab, install the basin, run vented discharge), or an up-flush system (no demolition: deliver, plug in, plumb the small-bore discharge up to the gravity drain).
The up-flush wins on cost and speed for single-fixture or small-bath retrofits, and it’s the only option for renters with landlord permission to add a toilet but not to break concrete. The trade-offs are real: up-flush systems are limited in fixture count and need attentive use — wipes and feminine products jam macerators in a way they don’t jam ejector pumps.
When you’ll encounter this term
- Adding a basement bath to a Seattle bungalow or Tacoma daylight-basement home.
- An ADU build-out in a converted garage or basement room.
- A vacation cabin or addition where running gravity drain to the new fixture is impractical.
- An older WA home where the existing basement bathroom sits behind a Saniflo unit.
Common variants and not the same as
- Up-flush vs. sealed sewage-ejector basin. Up-flush is a small surface-mounted packaged unit, suitable for one or two fixtures. Ejector basin is an in-floor sealed pit serving a full bath group, vented to the home’s DWV. The basin is more capacity, more demolition.
- Up-flush vs. standalone macerator pump. Up-flush is the consumer-facing packaged tank-plus-pump-plus-toilet product. A macerator pump is the engine; up-flush is the engine plus the carrier vehicle.
- Saniflo Up (toilet only) vs. Sanibest (multi-fixture). Different model capacities — Sanibest can also handle a sink or shower discharge into the same unit.
Common failure modes
- Macerator jam from foreign object — wipes, feminine hygiene products, dental floss. Manual unjamming is usually possible through the access plate.
- Pump motor failure — typically the unit gets replaced rather than rebuilt, since the cost difference is small.
- Discharge tubing kinked or partially blocked — pump runs but waste backs up into the tank; the high-water cycle fault triggers.
- Vent failure — odor in the basement. The unit MUST be properly vented per UPC; AAV-only is generally not allowed in WA.
Washington note
Up-flush systems are common in Seattle, Tacoma, and Bellingham basement-bathroom retrofits where the sewer line is above the basement floor and slab demolition is unappealing. Under the Uniform Plumbing Code (which WA adopts with state amendments), up-flush units must have proper atmospheric venting; AAV-only installation is generally not accepted by WA AHJs. Older homes that lack adequate vent stack capacity may need a vent extension before a Saniflo install can be permitted.
A few practical PNW notes:
- Confirm adequate vertical lift to the gravity drain before purchasing — most consumer units are rated for 12–15 feet of vertical lift plus reasonable horizontal run.
- Multiple fixtures (toilet + sink + shower) require a higher-capacity model like Saniflo Sanibest or Liberty Ascent II.
- For ADU builds in a King County or Pierce County jurisdiction, check with the AHJ before installing — venting and fixture count rules vary between cities.
FAQ
Can a Saniflo handle a full bathroom?
Single-fixture units (Saniflo Up) handle the toilet only. Multi-fixture units (Saniflo Sanibest, Liberty Ascent II, Zoeller Qwik-Jon Ultima) handle a full bath — toilet, lavatory, and shower — but each fixture must connect through the unit, not bypass to a separate drain.
Do I need a permit for a Saniflo in WA?
Yes, in nearly all cases. Adding a fixture (especially a toilet) requires a plumbing permit through the local AHJ. The permit covers the new fixture, the discharge tie-in to the gravity drain above, and the venting. Up-flush systems aren’t an exemption from the permit process.
Why is the unit making noise after each flush?
Most up-flush units run for 10–30 seconds after a flush as the macerator and pump clear the tank, then a brief check-valve close. Continuous running, sustained loud grinding, or short cycling (running every few seconds) indicates a jam, a blocked discharge, or a failed check valve — not normal operation.