Spec-by-Spec Comparison
Detailed Comparison
Niagara internal comparison of two different flush technologies at different efficiency tiers. The Stealth Sabre (0.8 GPF, vacuum-assist) is the brand's water-conservation flagship. The Phantom (1.6 GPF, gravity) is the traditional value pick.
Vacuum-assist flush mechanism
The Stealth Sabre uses Niagara's signature vacuum-assist technology. A sealed chamber inside the tank pulls air out of the trapway during flush, creating suction that pulls bowl contents down. The result: 0.8 GPF effective flushing with clearing power comparable to 1.6 GPF gravity flush.
The Phantom uses conventional gravity-feed at 1.6 GPF. Water from the tank falls through the flush valve into the bowl via gravity. Quieter, simpler, but uses 2x the water per flush.
Water consumption
4-person household at typical 20 flushes/day:
- Stealth Sabre: 5,840 gallons/year
- Phantom: 11,680 gallons/year
Difference: 5,840 gallons annually saved. At average $11 per 1,000 gallons combined water+sewer, that's $64/year. Over 20 years: $1,280 in water bill savings.
Initial cost
Stealth Sabre: $250-310. Phantom: $180-220. Sabre premium: $70-90. Payback period: roughly 14 months on water bills alone.
Reliability and maintenance
Vacuum-assist has slightly more complex internal mechanism than pure gravity. Vacuum-assist requires occasional cleaning of the vacuum chamber. Gravity flush requires occasional flapper replacement (similar service intervals).
Drought and rebate considerations
In drought-priced markets (California, Arizona, Nevada, Texas), tiered water rates make the Stealth Sabre's savings 2-3x higher. Many California water districts offer $100-200 rebates specifically for vacuum-assist toilets, reducing Sabre's effective price to $50-110.
Long-term winner
Over a 20-year ownership, the Stealth Sabre saves $1,280 in water bills, qualifies for $100-200 in rebates, and pays back its $70-90 premium in 14 months. The Phantom offers slightly lower upfront cost and simpler mechanics, but the math favors the Sabre.
Final Verdict
We recommend the Niagara Stealth Sabre for any household serious about water conservation — 50% less water per flush with comparable clearing power, $64/year in operating savings, and quick payback. The Phantom is the safer choice for buyers uncertain about vacuum-assist mechanics or installing where supply pressure is unreliable.
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Buy Niagara — Check current pricePros & Cons Side-by-Side
- Lowest-flow gravity toilet IAPMO-certified in the US (0.8 GPF)
- EPA WaterSense Most Efficient list every year since 2014
- Vacuum-assist trapway — flush velocity comparable to pressure-assist without the noise
- Highest rebate amounts in CA, AZ, TX, NV utility programs (typically $75-$200)
- Saves ~9,800 gallons/year vs 1.6 GPF and ~3,500 vs 1.28 GPF
- Universal Height (17.25") + elongated bowl
- MaP 800g — solid waste-clearance performance at half the water volume
- 5-year warranty on vacuum-assist trapway mechanism
- Standard ceramic glaze (no hydrophobic upgrade available)
- Slightly louder flush than gravity-only (vacuum activation has audible whoosh)
- Less common at retail — primarily through Home Depot Pro Desk + plumbing supply
- Vacuum dome mechanism is Niagara-proprietary (~$45 replacement at end-of-service-life)
- Stealth-specific flapper required ($15) — universal flappers don't maintain vacuum
- Limited color availability (primarily White)
- Older homes with partial drain obstructions may need flush volume above 0.8 GPF
- 1.6 GPF flush provides reliable waste clearance even in older drain lines
- MaP 850g — solid waste-clearance performance
- Universal 3-inch flush valve — Korky/Fluidmaster parts fit perfectly
- Comfort Height (16.5") + elongated bowl
- Niagara brand pedigree at value-tier price
- Suitable for landlord rebuilds where 1.6 GPF is the spec requirement
- No proprietary vacuum mechanism — simpler service than Stealth
- Good for older homes with partial drain-line obstructions
- NOT WaterSense certified (1.6 GPF exceeds 1.28 GPF threshold)
- Not rebate-eligible in any US utility program
- Higher water usage — meaningful in drought-zone tiered water rates
- Standard ceramic glaze (no hydrophobic upgrade)
- SoftClose seat NOT included
- No designer styling — strictly utility aesthetic
- Less retail availability than Cadet 3 or Cimarron at similar price tier