Water Reuse in Buildings as Part of the Solution to a Growing Water Crisis

By Erin Sanchez and Sarah Thomas

Water reuse is an important aspect of a sustainable future, especially in drought prone areas of the world such as California and other southwestern states. It is also increasingly important as climate change trends towards a hotter and dryer future. The western Unites States has experienced the driest 22-year period in more than 1,200 years. 

In addition, despite a drought breaking winter and record snowpack this season, the Colorado River, which supplies water to 40 million people and over 5.5 million acres of crops, is still severely over allocated. One rainy season will not be enough to reverse the trends of the last 22 years. Lake Mead and Lake Powell, the two largest reservoirs in the country, are both supplied by the Colorado River. Each are currently at 28% and 22% of capacity respectively. This is 34-36% less than the historic average. Water levels are so low that they may soon fail to turn the turbines that generate electricity. Consequently, the states that rely on the Colorado River will likely face not only a water shortage, but also power grid disruptions. 

Last summer, the federal government mandated that the states relying on the Colorado River come to an agreement and plan to reduce water use by 20-40% of the river’s flow. Up to this point, the states have been unable to reach an agreement and in an unprecedented move, the federal government has stepped in to draft a plan which will allocate the water and mandate reductions. The plan is expected to be delivered this summer. While this news may seem grim, many water resource professionals and leaders agree that this is not a result of a water supply problem, but in fact a water management problem. With this view in mind, there is some optimism that the water crisis can be addressed through resource management efforts to create a sustainable and equitable future for all states. 

In California, Urban Water Use makes up around 10% of total usage. The main proportions of usage are in Residential, Commercial, Institutional, and Industrial sectors respectively. While Agriculture makes up the bulk of water use in California, we should aim to improve water management across all sectors. With the rapid improvements of water reuse technologies, we can aim to close the loop - reducing wastewater and ultimately our reliance on precious freshwater resources. 

There are many ways we can help combat this resource management problem. In buildings, multifaceted strategies include decreasing, optimizing, and reusing water - all of which are pieces of the puzzle. Efforts to decrease water use can involve installing low flow and flush fixtures, and landscaping with native and adaptive plants that require little or no irrigation.  Water reuse systems focus on utilizing water from sources that have traditionally been regarded as waste products. 

Repurposed wastewater sources include graywater, blackwater, condensate from cooling towers, groundwater, and stormwater. One water reuse strategy is the collection of foundation drainage for water supply. Methods such as this simultaneously solve a nuisance problem, while providing a source of usable water to the building after treatment. In large commercial and residential buildings, onsite water treatment technologies are another example of water reuse. The clean, treated water is then recirculated into the building’s non-potable water supply, often meeting up to 95% of the total building water demand. This can serve to reduce the reliance on strained fresh water supplies. Water reuse strategies are often a win-win. 

Here in Los Angeles, City National Plaza is installing a water reuse treatment system by EpicCleanTec. This system would treat an estimated 14,900,000 gallons of water annually, providing nearly $500,000 per year in local rebates and utility savings. This equates to a payback of 8-10 years. From an investment perspective, building owners can insulate their investments from increasing uncertainty in the cost and availability of water supplies by incorporating a variety of water reuse strategies. 

As these technologies improve, a shift in local regulations has also been observed. These regulations are starting to incentivize and, at times, require buildings to incorporate secondary water sources such as municipally reclaimed water supplies, water catchment systems, and maybe one day on-site wastewater treatment and reuse technologies. As we continue to face uncertainty in the future of our water resources, it is more important than ever that we look to all industries to spearhead solutions to our water management crisis.