Source
doi:10.1016/j.jclepro.2022.131125 — original publication (opens in a new tab; the file is not redistributed)
Domain: d03_water_waste_circular · SSI: i07_fulfilment_basic_needs, i09_environmental_sustainability
Summary
LCA study comparing a hybrid decentralized water system (RWHS + GWRS) against a centralized water system (CS) for a single-family high-water-consumption household in Bucaramanga, Colombia (4 inhabitants, 309 m³/year, 1053 mm/year rainfall). Using GaBi software and the ReCiPe 2008 method across 13 midpoint and 3 endpoint categories, the hybrid system achieves 42.5% potable water savings and 20% reduction in wastewater flows, outperforming the CS in 12 of 13 midpoint categories and all 3 endpoint categories. Operational phase dominates environmental impact (>85% of most categories); construction is negligible except for ozone depletion (88% construction-phase due to PVC). Provides LCA methodology, water savings ratios, and system sizing benchmarks transferable to NZ community-scale decentralized water design.
Key claims
Water savings performance
- Hybrid RWHS+GWRS achieves 42.5% potable water saving (131 m³/year) vs centralized system for a 4-person household at 309 m³/year total demand; RWHS contributes 22.8% (70.6 m³/year), GWRS 19.6% (60.7 m³/year). LIT_008
- Potable water used for non-potable purposes: HS = 42 m³/year vs CS = 173 m³/year — HS reduces over-treatment of drinking-quality water by 75.7%. LIT_008
- WTP demand: HS = 178 m³/year vs CS = 309 m³/year (−42.4%). WWTP discharge: HS = 237 m³/year vs CS = 297 m³/year (−20%). LIT_008
- RWHS covers non-potable indoor uses (internal tap, external tap, washing machine, sink) = 36.1% of total household water use; GWRS covers toilet flushing only = 19.6%. LIT_008
System sizing and specifications
- Household context: 4 inhabitants, 101 m² roof catchment area, 1053 mm/year average annual rainfall (15-year record), 203 L/capita/day baseline consumption. LIT_008
- RWHS storage: 2 × 1,100 L HDPE tanks (2,200 L total); first flush diverter 102 L (~1 mm precipitation); treatment train: leaf filter → coarse filter → anti-plague mesh → self-cleaning filter → dual storage → sodium hypochlorite 10% disinfection. LIT_008
- GWRS storage: 300 L principal HDPE storage tank + 55 gal setoff tank; treatment train: grease trap (300 L) → 2 × slow sand filters (55 gal each, parallel) → sodium hypochlorite 10% disinfection; greywater source: showers only. LIT_008
- RWHS pumping energy: 9.9 kWh/year. GWRS pumping energy: 10.7 kWh/year. Total HS operational electricity: 20.55 kWh/year — for 131 m³/year delivery = 0.157 kWh/m³ effective pumping intensity. LIT_008
Maintenance and lifespan
- System lifespan: 50 years. Electromechanical components (pumps, valves, level sensors): 15-year replacement cycle. Slow sand filters: replaced every 8 years. Coarse filters: replaced annually. LIT_008
LCA performance — midpoint indicators (ReCiPe 2008, per 1 m³, including WTP/WWTP)
| Category | Unit | HS | CS | HS better? |
|---|---|---|---|---|
| Climate change | kg CO₂ eq. | 1.99 | 2.44 | ✓ |
| Fossil depletion | kg oil eq. | 0.403 | 0.476 | ✓ |
| Freshwater ecotoxicity | kg 1,4-DB eq. | 5.10×10⁻³ | 6.43×10⁻³ | ✓ |
| Freshwater eutrophication | kg P eq. | 1.13×10⁻³ | 1.43×10⁻³ | ✓ |
| Human toxicity | kg 1,4-DB eq. | 0.183 | 0.231 | ✓ |
| Marine ecotoxicity | kg 1,4-DB eq. | 5.18×10⁻³ | 6.48×10⁻³ | ✓ |
| Marine eutrophication | kg N eq. | 7.52×10⁻³ | 9.44×10⁻³ | ✓ |
| Metal depletion | kg Fe eq. | 0.180 | 0.190 | ✓ |
| Ozone depletion | kg CFC-11 eq. | 3.17×10⁻¹² | 7.04×10⁻¹³ | ✗ (HS worse) |
| Photochemical oxidant | kg NMVOC eq. | 2.66×10⁻³ | 3.09×10⁻³ | ✓ |
| Terrestrial acidification | kg SO₂ eq. | 2.85×10⁻³ | 3.22×10⁻³ | ✓ |
| Terrestrial ecotoxicity | kg 1,4-DB eq. | 9.16×10⁻⁵ | 1.16×10⁻⁴ | ✓ |
| Water depletion | m³ | 3.32 | 4.68 | ✓ |
- Ozone depletion is the one category where HS performs worse; PVC in RWHS/GWRS components accounts for >95% of this impact in both systems — PVC pipe specification is the key environmental trade-off in RWHS/GWRS design. LIT_008
- Centralized WTP + WWTP account for >60% of environmental impact in 7 of 13 categories for the CS — centralized water infrastructure is the dominant environmental burden. LIT_008
LCA phase contributions — Hybrid System
| Category | Construction | Operation |
|---|---|---|
| Climate change | 7.5% | 92.5% |
| Fossil depletion | 16.9% | 83.1% |
| Metal depletion | 18.3% | 81.7% |
| Ozone depletion | 88.0% | 12.0% |
| Photochemical oxidant | 11.7% | 88.3% |
| Terrestrial acidification | 8.1% | 91.9% |
| All remaining categories | <3% | >97% |
Operational phase dominates for all categories except ozone depletion (88% construction-phase, driven by PVC manufacturing). Design optimization should target operational energy efficiency rather than embodied material minimization.
Cross-study benchmarks
| Study | Country | Occupants | Water demand | Rainfall | Best system | Win ratio |
|---|---|---|---|---|---|---|
| Leong et al. (2019) | Malaysia | 5 | 427 m³/yr | 2533 mm/yr | RWHS | 5/6 |
| Kobayashi et al. (2020) | Canada | 5 | 190 m³/yr | N/A | GWRS + constructed wetland | 2/3 |
| Marinoski & Ghisi (2019) | Brazil | 4 | 232 m³/yr | 1518 mm/yr | HS | 9/13 |
| This study | Colombia | 4 | 309 m³/yr | 1053 mm/yr | HS | 12/13 |
HS outperforms CS most comprehensively at higher water demand and moderate rainfall — consistent with Neobiome’s expected NZ context.
Neobiome Intelligence relevance
D03 — Water, Waste & Circular Systems: Primary empirical LCA benchmark for RWHS+GWRS hybrid water systems. Key design parameters: 2,200 L RWHS storage (2×1,100 L) delivers 22.8% demand coverage; 300 L GWRS storage from showers alone delivers 19.6%; combined 42.5% savings at 203 L/capita/day baseline and 1053 mm/year rainfall. Operational energy is low (0.157 kWh/m³ delivered). NZ recalibration required: NZ average ~165 L/capita/day and highly variable rainfall (600–8,000 mm/year range) will shift the savings ratio — higher NZ rainfall generally increases RWHS coverage; lower per-capita demand reduces the absolute volume to displace.
I07 — Fulfilment of Basic Needs (water): 42.5% potable water savings directly quantifies achievable household-scale WSR from RWHS+GWRS alone. Reduction of WTP demand from 309 to 178 m³/year and WWTP discharge from 297 to 237 m³/year quantify the infrastructure independence contribution. This is the most directly comparable empirical WSR benchmark in the wiki.
I09 — Environmental Sustainability: LCA validation that decentralized RWHS+GWRS is environmentally superior in 12/13 midpoint and all 3 endpoint categories. The operational phase dominance finding (>85% of impact in 12 categories) means NI environmental assessment of water systems should focus on long-run operational energy and water use patterns, not embodied materials.
Research targets
Documents to retrieve
- [RT_044] Kobayashi et al. (2020) — LCA of decentralized GWRS (constructed wetlands, membrane bioreactors) at community, neighbourhood, and single-household scale in Canada; explicitly multi-scale — directly applicable to Neobiome community-scale water design (Urban Water J. 8(11), doi:10.1080/1573062X.2020.1711420). → D03, I09
- [RT_045] Marinoski & Ghisi (2019) — environmental performance of hybrid RWHS+GWRS in single-family households in Brazil; HS outperforms CS in 9/13 midpoint LCA categories (Ambiente Construído 18(1):423-443). → D03
Connections
Links to
SSI indicators (2): I07: Fulfilment of Basic Needs · I09: Environmental Sustainability
EDT domains (1): D03: Water, Waste & Circular Systems
Referenced by
SSI indicators (2): I07: Fulfilment of Basic Needs · I09: Environmental Sustainability
EDT domains (1): D03: Water, Waste & Circular Systems
Technologies (1): Greywater Recycling
Sources (1): OT_036