What Water Stewardship Means for Buildings
Water stewardship in buildings goes beyond consumption reduction — it encompasses responsible sourcing, efficient use, quality management, and discharge control. In Bangladesh, where water is simultaneously abundant (monsoon flooding) and scarce (dry season shortages, groundwater depletion), building water management has environmental and operational significance.
Key Water Metrics
| Metric | Good Practice (Office) | Average | Poor |
|---|---|---|---|
| Water use intensity | 0.5–1.0 m³/m²/yr | 1.0–1.5 m³/m²/yr | > 2.0 m³/m²/yr |
| Per capita water use | 30–50 L/person/day | 50–80 L/person/day | > 120 L/person/day |
| Cooling tower cycles of concentration | 5–7 cycles | 3–5 cycles | < 3 (excessive blowdown) |
| Leak detection | Night-time flow ≤ 5% of peak | 5–10% | > 10% (active leaks) |
| Rainwater harvesting | Captures ≥ 50% of rooftop runoff | System exists but partial | No collection system |
Water Efficiency Measures
- Low-flow fixtures: Sensor taps (1.9 L/min), dual-flush toilets (3/6L), low-flow showerheads (7.6 L/min). Saves 30-40% vs conventional fixtures.
- Cooling tower optimization: Increase cycles of concentration through water treatment — reduces make-up water by 20-30%.
- Leak detection: Install flow meters on main supply; compare night-time vs daytime flow. Continuous monitoring catches leaks early.
- Rainwater harvesting: Collect rooftop runoff for toilet flushing, irrigation, cooling tower make-up. Particularly effective in monsoon Bangladesh.
- Greywater recycling: Treat handwash and shower water for toilet flushing. Reduces potable water demand by 20-30%.
- Irrigation efficiency: Drip irrigation, native/drought-tolerant landscaping, weather-based controllers.
Bangladesh Context
- Groundwater depletion: Dhaka's water table has dropped 2-3 metres per decade. Deep tubewells are going deeper. Reducing building water consumption directly addresses this crisis.
- WASA supply: Intermittent piped supply means most buildings rely on groundwater + storage. Conservation reduces dependence on declining aquifers.
- Monsoon abundance: Dhaka receives ~2,000 mm annual rainfall. Rainwater harvesting captures this resource for non-potable use.
- Water quality: Arsenic and iron in groundwater require treatment. Municipal supply requires filtration. Water quality testing is essential.
References
Insights & Guidance
- Water use intensity benchmark: 0.5-1.0 m³/m²/yr for offices. Above 2.0 indicates waste or leaks.
- Low-flow fixtures save 30-40% water with immediate payback.
- Night-time flow analysis detects leaks: >10% of peak flow = active leak problem.
- Dhaka groundwater table dropping 2-3 m/decade — conservation is an environmental imperative.
- Rainwater harvesting is highly effective in Bangladesh (2,000 mm annual rainfall).
Water scarcity is intensifying in Dhaka despite Bangladesh being a water-rich country. Groundwater depletion threatens long-term building water supply. Water damage (from leaks and flooding) is the most expensive building insurance claim category. For ESG reporting, water stewardship is a core metric under GRI 303 and LEED Water Efficiency credits.
- Groundwater depletion — borehole runs dry or yields decline; building loses water supply.
- Contamination — arsenic or bacterial contamination of groundwater or storage tanks.
- Undetected leaks — concealed pipe leaks waste water and cause structural damage.
- Cooling tower water waste — poor treatment leads to excessive blowdown and scale.
- Water consumption records (monthly meter readings)
- Water quality test reports (annual)
- Leak detection survey results
- Cooling tower water treatment records
- Rainwater harvesting system records (if installed)
- Fixture types — sensor taps, dual-flush toilets, or old conventional fittings?
- Visible leaks — running taps, dripping pipes, toilet cisterns running continuously.
- Water meters — installed, read, recorded?
- Rainwater collection — system present? Functional?
- Cooling tower — water treatment equipment present?
- What is the monthly water consumption (m³)?
- What is the water source — WASA, borehole, or both?
- Are low-flow fixtures installed?
- Is there a rainwater harvesting system?
- Is cooling tower water treatment managed? What are the cycles of concentration?
- Water audit — water efficiency consultant for consumption analysis and savings identification.
- Rainwater harvesting design — hydraulic engineer for system sizing.
- Water quality issues — environmental laboratory and water treatment specialist.