The Solaire High-Rise Water Reuse System
A documented decentralized non-potable MBR reuse project in Battery Park City, New York
The Solaire is a 293-apartment, 27-story Battery Park City building with an on-site basement wastewater-recycling plant. Public sources describe an integrated non-potable reuse system—not a potable-water plant—and report historical results using different dates and measurement boundaries. The figures below retain those boundaries rather than combining them into a single headline percentage.
1. Site context and constraints
The project emerged under Battery Park City Authority environmental guidelines addressing water conservation, energy efficiency, and related building measures. Its on-site advanced water-treatment proposal was not then a routine New York City building-code pathway, so the project required early coordination with public agencies, building designers, operators, and the water/sewer authorities.
The system collected combined building wastewater rather than only greywater. That avoided the need for two separate wastewater collection systems, but it also meant that collection, pretreatment, biological treatment, membrane operation, disinfection, storage, cross-connection protection, and residuals handling had to fit into a high-rise basement and operate alongside normal municipal-water backup.
2. Documented process and reuse boundary
flowchart TB A[Combined building wastewater] --> B[Trash removal and pretreatment] B --> C[Anoxic biological zone] C --> D[Aerobic biological zone] D --> E[MBR hollow-fiber filtration] E --> F[UV and ozone polishing] F --> G[Treated-water storage] G --> H[UV recirculation for stored water] H --> I[Toilet flushing] H --> J[Air-conditioning make-up] H --> K[Landscape irrigation] L[New York City water] --> M[Backup and full switchover] E --> N[Periodic solids discharge to sewer]
The reuse stream was documented for toilet flushing, air-conditioning make-up water, and irrigation. It was not presented as potable water. The separate rainwater system should not be confused with the wastewater-reuse train; public descriptions treat those as distinct systems.
3. Design decisions and operating safeguards
- Demand matching: the selected non-potable end uses created a building-scale demand for reclaimed water while avoiding direct potable reuse.
- Biological and membrane treatment: the documented train used anoxic/aerobic treatment, modified Ludzack–Ettinger nitrogen removal, aluminium-based phosphorus removal, and an MBR. A 2021 technical analysis describes a 0.04 µm hollow-fiber membrane.
- Disinfection and storage: UV and ozone followed the MBR, and stored water was recirculated through UV to limit regrowth.
- Resilience: public documentation describes the ability to switch completely to New York City water when required.
- Integration: plant access, storage, controls, collection routing, non-potable distribution, residuals removal, and agency approvals needed to be resolved as part of the building design rather than after construction.
4. Historical reported outcomes
| Metric | Reported value and boundary |
|---|---|
| Plant rating | 25,000 US gal/day (approximately 94.6 m³/day); a rating or maximum, not proof of constant actual flow. |
| Building scale | 293 apartments; 27 stories. |
| Potable water and sewage | New York State DEC reported 48% less potable water per apartment and 63% less sewage versus comparable NYC buildings. |
| Indoor potable water | High Performing Buildings reported 43% lower indoor potable-water use; its 2007 example showed 19,555 gal/day reuse supply out of 52,618 gal/day total building water use. |
| Technical-economic analysis | A 2021 study reported approximately 50% lower potable demand and 60% lower wastewater flow since 2003–04, plus historical heat-recovery and energy observations. |
| Cost caution | The same study reported historical operating-and-maintenance cost of $2.84/m³ versus a model estimate of $0.62/m³; small-scale cost data were limited. |
5. Limitations and transferability
- The public evidence is historical and does not establish the current plant configuration, permit status, effluent quality, membrane-integrity testing, uptime, or current operating cost.
- Water-balance results vary by year, comparison building, and boundary. The published 43%, 48%, 50%, and 60% figures should not be collapsed into one universal current result.
- A high-rise reuse system still needs an additional water source because water is lost through end uses, evaporation, treatment residues, and other pathways. Reuse does not close the water loop by itself.
- Economics depend on building occupancy, simultaneous toilet/cooling/irrigation demand, local water and sewer tariffs, maintenance capability, space, energy prices, and approval requirements.
- Do not transfer the historical treatment train to another building without current source-water characterization, pathogen and chemical-risk assessment, cross-connection controls, vendor/OEM review, and jurisdiction-specific approval.
6. Transferable lessons for decentralized MBR projects
- Start with a quantified non-potable demand profile and size storage around actual daily variability.
- Keep potable backup and automatic fail-safe arrangements visible in the process design and operating procedures.
- Separate water-reuse claims by end use, time period, and denominator; a “reuse rate” without a boundary can mislead.
- Include maintainability, access, residuals handling, chemical storage, odour/noise design, cross-connection protection, and operator response in the concept stage.