Reverse Osmosis Can Extend Access to Potable Water

Reverse Osmosis Can Extend Access to Potable Water

Sustainable Investing

The purification technology enables doing more with less water

In 2021, a drought in Taiwan crippled the global microchip industry, Cape Town, South Africa, nearly ran out of water, and Chennai, the “Detroit of India,” actually did run out of water. By 2022, Lake Mead, the largest-capacity reservoir in the United States, was at a historic low, and the mighty Mississippi River became unnavigable in places due to low water levels. Is the global fresh water crisis really as bad as it seems?

Yes, it is, and it’s hard to make a case that it’s not going to get much worse. While many drought-prone regions may experience temporary relief during wet years, climatology paints a picture of increasing aridity. Fortunately, there are technologies that can help populations and economies prosper with less fresh water from natural sources. At the heart of these technologies is a treatment process called reverse osmosis (RO).

Reverse Osmosis Benefits

RO purifies water by pushing it through membranes that reject contaminants. It can be used to desalinate brackish water or seawater, or to purify other sources of water, including stormwater, surface water, groundwater, or wastewater from city sewers or industry.

Combined with other processes, RO can produce an effluent suitable for recharging depleted aquifers, which can support agriculture, stop ground subsidence, and restore the environment. RO can transform wastewater into drinking water purer than water from natural springs. It can even help deliver ultrapure water for the semiconductor and pharmaceutical industries.

While significant CAPEX was once a concern, there are new financing models that require no upfront capital (Water-as-a-Service® from Seven Seas Water Group, being one). Reverse osmosis is now becoming available to more businesses and municipalities than ever before.

Reverse Osmosis Drawbacks

RO desalination projects frequently don’t get off the drawing board due to high energy consumption, concern over environmental impact of brine, or associated costs.

But RO desalination’s closest competitor, thermal distillation, requires a whopping 10 times as much energy as RO. While large-scale thermal desalination plants are still in service, especially in the Mideast, where energy costs are low, RO is by far the most popular desalination process globally.

After recent efficiency breakthroughs, price points for desalinated water have dropped, making desalination more affordable than ever. And, thoughtful siting of plants has also been shown to mitigate brine’s environmental impact.

Plentiful brackish water exists far inland in arid areas like the American West, and the cost of desalinating brackish water is significantly lower than seawater desalination. For example, when complete, an RO desalination plant in the City of Alice, Texas, will desalinate brackish water from the local aquifer, lowering raw water prices and delivering municipal water independence.

RO is more costly than pumping fresh water from natural sources was back in the good old days, but when desalination is the best or only alternative, RO is the most efficient and effective process. Water treatment companies and governments are going out of their way to make even costly infrastructure viable.

Wastewater can be treated with RO for applications like aquifer recharge.

In California, the Orange County Water District’s Groundwater Replenishment System, for instance, is putting water back into the aquifer underfoot, driving saline intrusion back toward the coast.

Wastewater reuse with reverse osmosis also shares desalination’s high initial cost, and it can also face psychological barriers. As reuse applications come closer to human consumption, for instance agricultural irrigation and indirect potable reuse, the well-known “yuck factor” often kicks in. But, given the need for water, education campaigns can reduce the public’s reluctance to embrace potable reuse.

While RO-based systems are capable of producing water at virtually any level of purity, it’s important to get it right when water treated by RO is destined for human consumption, directly or indirectly. RO is too important to the future to damage the public trust.

Reverse Osmosis Can Extend Access to Potable Water