Water Efficiency as a Core Building Performance Metric

Why water resilience is the next frontier for green buildings in South East Asia and what developers need to build in now

When developers and investors talk about building performance, the conversation defaults quickly to energy: kilowatt-hours, carbon intensity, solar yield. Water rarely commands the same attention. That is a miscalculation, particularly in South East Asia, where the conditions that determine a building's long-term operational viability are shifting around water as much as around energy.

A region under growing pressure

South East Asia is not short of rainfall. The paradox is that the region faces serious water stress anyway. Rapid urbanisation concentrates demand faster than infrastructure can respond. The Asian Development Bank estimated that by 2030 there will be a 40% shortfall between water supply and demand across the region. ¹ IDRICA

The pressure is structural, not cyclical. Research integrating economic, emissions, climate, and population projections finds a high risk of severe water stress in densely populated watersheds by 2050, with water needs related to socioeconomic changes likely to increase considerably and often overshadow the direct effects of climate change on water resources. ² nih

The 2025 Asian Development Bank Water Development Outlook adds further detail. More than half of South East Asian countries showed a declining environmental water security trend between 2013 and 2025, driven by increased hydrological alteration, groundwater depletion, and riparian vegetation loss. In urban areas, rapid growth has led to escalating risks from flooding, particularly in countries like Indonesia and the Philippines, where drainage indicators have declined since 2013. ³ Asian Development Bank

The pattern is one of simultaneous excess and scarcity: too much water in the wrong place, too little reliable supply in others. For building owners, both conditions carry cost.

What this means for operational costs

Water tariffs in South East Asian cities have been rising, and the trajectory is upward as governments grapple with the cost of maintaining and expanding aging infrastructure. Buildings that rely on uninterrupted municipal supply without redundancy face exposure on two fronts: cost and continuity.

The opportunity at the building level is real. Research shows that up to 40% of a building's water usage can be replaced by treated greywater, reducing dependence on municipal supply and lowering utility bills. ⁴ Commercial buildings are particularly well positioned to act. Due to their large potential collection areas and high potential demand for non-potable water, commercial and industrial buildings are largely better candidates for the retrofit of rainwater harvesting systems. Greater savings can also be achieved when these systems are installed during construction rather than added later. ⁵ Constructive VoicesSusdrain

The integration of rainwater harvesting with greywater recycling compounds the benefit. Implementing both systems in buildings can reduce freshwater consumption and decrease the discharge of wastewater to the environment, ⁶ a double gain that matters both for operating costs and for regulatory standing. Planningmalaysia

Building-level strategies worth specifying now

Three categories of intervention deserve attention in any new development or major renovation.

Rainwater harvesting offers significant potential in Southeast Asia, where annual rainfall levels are generally high. The financial performance of these systems varies depending on the application and scale, but studies have found payback periods of as little as two years, depending on building type, catchment area, and local water tariffs.⁸ ScienceDirect

Greywater recycling. Wastewater from sinks, showers, and washing machines can be treated and reused for toilet flushing, irrigation, and cooling tower makeup, reducing demand for potable water. Greywater reuse systems can be combined with measures such as rainwater harvesting, drip irrigation, and low-flow fixtures to further improve overall water efficiency. ⁹  UGREEN

Building-level water metering ties all of this together. Without sub-metering, consumption data is unavailable, and savings cannot be verified, managed, or reported.

What the certification frameworks require

The three major green building certification systems each address water differently, and each provides useful guidance for project teams.

Under LEED, water efficiency is a dedicated credit category. LEED addresses water use as part of its holistic credit framework, covering credit categories tailored to each rating system, from new construction through to operations and maintenance. ¹⁰ Prerequisites under LEED v4 cover outdoor water use reduction, indoor water use reduction, and building-level water metering, establishing a baseline of accountability before credits can be earned. ⁷ Water efficiency is described by practitioners as an especially productive area when looking at existing buildings or pursuing LEED v4 Operations and Maintenance credits. ¹¹ USGBC + 2

LEED v4 requires that all newly installed toilets, urinals, private lavatory faucets, and showerheads that are eligible for labelling carry WaterSense labelling, and that buildings reduce aggregate water use 20% from the baseline. ⁷ This is a floor, not a ceiling. Sloan

Under EDGE, water is one of three equally weighted categories alongside energy and materials. EDGE requires a minimum projected reduction of 20% in energy use, water use, and embodied carbon in materials as benchmarked against a standard local building. ¹² EDGE Certified requires at least 20% reductions in energy use, water consumption, and embodied energy in materials compared to a standard local building, with EDGE Advanced requiring at least 40% projected energy savings on top of that baseline. ¹³ The EDGE App models these savings at the project level, using local climatic data, making it a practical tool for early-stage design decisions. EDGEuHoo

Under WELL, the water concept addresses quality as much as quantity. Certification under the WELL Building Standard requires buildings to undergo on-site water testing and other post-occupancy assessments, with reassessment needed every three years to maintain certification. ¹⁴ WELL performance testing for water quality requires a qualified professional to collect samples and verify that they meet the thresholds set out in the standard. ¹⁵ For occupier-facing buildings, offices, hotels, mixed-use, demonstrating water quality through a recognised framework is increasingly part of the tenant proposition. GbaKaiterra

Water risk and asset valuation

The link between water risk and long-term asset value is sharpening. The world's largest asset managers now recognise biodiversity, water, and soil as fundamental to long-term performance, with the World Economic Forum estimating the opportunity in nature-positive transitions at $10 trillion in annual business value and nearly 400 million jobs by 2030. ¹⁶ World Economic Forum

For building sector assets specifically, this translates into practical exposure. A building with no water resilience strategy, no sub-metering, no alternative supply sources, no redundancy against municipal disruption, is a building that carries unpriced risk. As extreme weather, food insecurity, and nature loss actively reshape economies and portfolios, resilience is becoming a financial imperative rather than a choice, with delay carrying the risk of stranded assets. ¹⁶ World Economic Forum

Green building certification does not insulate an asset from every climate-related risk. But it provides a structured, verified record of the measures that have been taken, which is increasingly what lenders, insurers, and institutional buyers require before committing capital.

The practical implication for developers

Water efficiency is not a feature to be added once a building is complete. It is a design decision, and the earlier it is integrated, the lower the incremental cost. A building designed from the outset with low-flow fixtures, rainwater collection infrastructure, and greywater recycling capacity will cost less to operate, carry lower climate risk, and be easier to certify than one retrofitted with the same systems after the fact.

In South East Asia, where water stress is structural and urban demand continues to grow, this is not a forward-looking consideration. It is already a present one.

Sources

1. Idrica — "The Ten Challenges of Water Management in South East Asia" (November 2023): https://www.idrica.com/blog/the-ten-challenges-of-water-management-in-southeast-asia/

2. Paltsev, S. et al. — "Projections of Water Stress Based on an Ensemble of Socioeconomic Growth and Climate Change Scenarios," NCBI (2016): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4814075/

3. Asian Development Bank — Asian Water Development Outlook 2025: https://www.adb.org/awdo/editions/2025

4. Constructive Voices — "Water-Efficient Building Systems: From Rainwater Harvesting to Greywater Reuse" (August 2023): https://constructive-voices.com/water-efficient-building-systems-from-rainwater-harvesting-to-greywater-reuse/

5. Ricardo / Susdrain — "Independent Review of the Costs and Benefits of Rainwater Harvesting and Grey Water Recycling": https://www.susdrain.org/files/resources/evidence/Ricardo_Independent-review-of-costs-and-benefits-of-RWH-and-GWR-Final-Report.pdf

6. Planning Malaysia — "Integrating Rainwater Harvesting and Greywater Recycling to Increase Water Efficiency in Office Buildings" (September 2023): https://www.planningmalaysia.org/index.php/pmj/article/view/1369

7. Sloan — "LEED v4 Water Efficiency Credits" (December 2016): https://www.sloan.com/blog/leed-v4-water-efficiency-credits-do-you-know-new-standards

8. ScienceDirect — "Minimum Cost Solution to Residential Energy-Water Nexus through Rainwater Harvesting and Greywater Recycling" (March 2021): https://www.sciencedirect.com/science/article/abs/pii/S0959652621009616

9. UGREEN — "EDGE Certification: The Complete Guide": https://ugreen.io/edge-certification-the-complete-guide/

10. USGBC — LEED Rating System Overview: https://www.usgbc.org/leed

11. Buildings.com — "LEED Certification Tips: Water Efficiency": https://www.buildings.com/resiliency-sustainability/article/10186126/leed-certification-tips-water-efficiency

12. EDGE Buildings (IFC / GBCI) — EDGE Certification Overview: https://edge.gbci.org/

13. uHoo — "What is EDGE Certification? A Guide to Green Buildings" (April 2025): https://getuhoo.com/blog/business/what-is-edge-certification-a-guide-to-green-buildings/

14. Green Building Alliance — WELL Building Standard Overview: https://www.gba.org/resources/project-and-product-certifications/well-building-standard/

15. KaiTerra — "Navigating the WELL Building Standard and Certification" (May 2025): https://learn.kaiterra.com/en/resources/navigating-the-well-building-standard-and-certification-a-cheat-sheet

16. World Economic Forum — "Why Investors Must Hone in on Sustainable Finance in 2025": https://www.weforum.org/stories/2025/09/sustainable-finance-in-2025-why-investors-can-t-afford-to-look-away/