ESG Initiatives and Health Risks: The Water Quality Trade-off in Green Buildings

Environmental Sustainability: The New Standard

Since the launch of the U.S. Green Building Council’s LEED (Leadership in Energy and Environmental Design) system in 1998, green building practices have reshaped modern construction. Designed to incentivize sustainability, LEED certification has become the gold standard for environmentally responsible building design, encompassing everything from energy efficiency to water conservation.

But there’s a hidden side to water-saving efforts in these buildings that deserves more attention: public health risks linked to water quality.

As we continue to embrace environmental, social, and governance (ESG) goals, it’s important to examine how some well-intended green design choices may unintentionally create conditions that put building occupants at risk, especially with regard to waterborne diseases and microbial contamination.

The Rise of Water Efficiency in Green Design

Water conservation is a central focus of green building standards like LEED. Projects can earn certification points by installing:

• Rainwater harvesting and graywater reuse systems

• Efficient irrigation systems

• Low-flow toilets, showerheads, and faucets

These measures are crucial for reducing our water footprint, especially in drought-prone areas. And they have been successful at making a measurable difference. For example, toilets have gone from using over 5 gallons per flush (gpf) in the 1980s to as low as 1.28 gpf today - a 74% reduction! Faucets, showerheads, dishwashers, and washers have seen similar improvements (see Table 1).

Table 1: A comparison of water use for different fixtures from the 1980s to modern green code requirements, showing the percent reduction of water use. (gpm – gallons per minute, gpf – gallons per flush)

But with all this progress in water conservation, we’re also encountering a new challenge: decreased water use can lead to degraded water quality.

How Water Conservation Can Backfire

Water in buildings doesn’t just flow, it rests. The time it takes for water to travel from the treatment plant to your tap is known as water retention time (WRT) or hydraulic residence time (HRT). Longer retention times, especially within building plumbing (called premise plumbing), can cause water to stagnate. This stagnation becomes a breeding ground for opportunistic pathogens like Legionella and Pseudomonas aeruginosa.

Why is this happening in green buildings?

1. Low-flow fixtures lead to slower water movement (and therefore higher WRT)

2. Larger pipes sized for higher flow (often for fire suppression systems) leads to more volume, more stagnation.

3. Reduced hot water temperatures for energy savings create ideal conditions for microbial growth

Water Age: The Forgotten Risk Factor

“Water age” is how long water has been sitting in a system. While centralized water distribution systems are designed for high throughput, premise plumbing in green buildings often has much higher water ages. This can total weeks or even months in some low-use areas.

Older water tends to have:

• Lower disinfectant residuals (like chlorine)

• Higher pipe corrosion risk (especially in copper piping)

• Greater amounts of leached metals

• Unpleasant taste and odor

• Increased microbial regrowth

And ironically, when these buildings try to solve water quality problems with routine flushing, it can appear wasteful—conflicting with the very green principles they were built upon.

What Can Be Done?

At Clear, we believe that sustainability and public health should go hand in hand. Water conservation shouldn't come at the cost of water safety.

Here’s how building owners and designers can mitigate these risks:

1. Shorten pipe runs and avoid dead-ends in plumbing

2. Right-size plumbing: use smaller diameter pipes to maintain water velocity

3. Install recirculating systems that maintain temperature and flow, with consideration of pathogen growth prevention

4. Use materials with lower biofilm potential, such as copper  

5. Maintain water quality at the point-of-entry (POE) with robust disinfection technologies

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Rethinking “Green” Water

Green buildings have transformed the way we think about sustainability. But as the number of certified buildings continues to climb, from under 7,500 in 2010 to over 75,000 by 2014, it is critical to understand the unintended tradeoffs and consequences of those designs.

Water conservation is crucial, but clean, safe water is non-negotiable. By incorporating water management strategies that prioritize both efficiency and quality, we can build healthier, more sustainable communities.

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