Guest Column | August 23, 2017

What's The Cheapest Source Of Water?

By Michael Kanellos

Seawater, sewers, conservation, or construction?

That is the question when it comes to water.

Despite a torrential winter in California and a call for building dams in D.C., communities around the world will need to tap into “alternative” sources of water like seawater desalination or water recycling more deeply and more often. Water consumption is expected to be 40 percent higher than today and 50 percent higher in developing countries, many of which are already enduring shortages and water stress.  Around 1.2 billion people, or almost one-fifth of the world's population, live in areas of physical scarcity.

So what’s the best alternative to try, or at least try first? Hands down, stopping leaks is the most economical option. Take a look at the statistics from Bluefield Research in the chart below.  Recovering water from leaks costs on average $1.21 per 1,000 gallons in the U.S. That’s less than half of the cost of traditional water, which clocks in a $3.90 per 1,000 gallons. Bluefield’s Erin Bonney Casey further breaks down the price of traditional water into $2.95 for processing and transmission and 95 cents for water rights.

At first glance, that doesn’t seem possible: recovered water is, after all, traditional water that just happens to get lost along the way. Shouldn’t it cost $5.11 per 1,000 gallons? ($2.95 plus $1.21). No. The $2.95 spent on processing and water rights is essentially a lost cost. You were already dripping it into the ground. The $1.21 costs revolves around revolving around things like repair costs and software and sensors for monitoring leaks. Put another way, recovered water comes pretreated and you don’t need to buy water rights from yourself.

And we lose a lot through leakage. A typical water utility can expect to lose 10 to 15 percent of its water to leaks, but some cities go far beyond that level. Chicago at one point lost over 50 percent of its water to leaks. Manila lost 67 percent and has reduced it to around 34 percent. A huge contributor is age. The U.S. has 1.2 million miles of water mains and the average age of the pipes in urban areas hovers around 80 years. Large, individual users can save too. The Seattle Mariners cut water consumption by 10 percent in part through leakage control. (See the earlier story.)

“Pipe repairs are definitely the cheapest option for expanding water supplies if you are losing water to leaks,” said Bonney Casey. “We should be investing in infrastructure maintenance ahead of new gold plated systems where possible.”

Recovered water — i.e., dirty water that gets purified for reuse — and desalination are even more expensive.

The California Public Utilities Commission (PUC) in a report from 2016 came to similar conclusions. Desalination is the most expensive, followed by recovered or recycled. Leakage, in fact, even was more cost-effective than conservation programs targeted at consumers. The PUC chart measures water in acre-feet: If you divide by 825, you get a dollars-per-thousand-gallons price. When you do that, conservation comes to $1.62, or 40 cents more per acre-foot.

Room for All

The other alternatives, however, fill important niches. In extremely dry regions like the Middle East, desalination is a must. The costs will also come down through technologies like forward osmosis. Water recycling and conservation, likewise, will be important in regions where water demand is climbing but leakage is under control. Recycling can also be implemented at individual sites. San Diego International Airport, for instance, has launched a trial to collect the condensation from its AC system and reuse the water for non-drinking purposes like hosing down runways. Approximately 80 percent of the airport’s water is not consumed by humans. An early estimate posits that the dew from the AC system comes to a million gallons per year.

“Water Recycling may be the holy grail of new water. It does not require customers to change their ways or invest in new technologies. Instead, it is the wastewater facilities that do the work,” the PUC report stated.

Within a decade, the alternatives likely won’t seem alternative at all.

Michael Kanellos is the Industry Champion for water at OSIsoft.