Background
Severe droughts have been decreasing water levels in water bodies across the western U.S. for over 20 years, and now this region is considered to be in a “megadrought” – a drought that has lasted two decades or longer. Lake Mead and Lake Powell, the two largest reservoirs in the Colorado River Basin, are rapidly drying up. Lake Mead provides drinking water to 25 million people in Arizona, California, Nevada, and New Mexico. Lake Powell is part of the area that provides hydroelectricity for 5.8 million homes and businesses and supplies 20 million people with water. In addition, groundwater is being depleted rapidly, forcing cities to limit construction and rethink future development.
Among reasonable solutions is desalination, the process by which seawater is transformed into fresh water. Currently, only a very small percentage of the U.S. population receives desalinated drinking water; there are approximately 400 municipal and 200 non-municipal desalination plants in the U.S., concentrated in California, Florida, and Texas.
As the U.S. is likely to increase its use of desalination in the coming decades, some public health issues need to be examined. In this article, I will discuss the experience of Israel, a country with decades of experience using this technology, and some of the public health issues that have arisen.
Desalination
Desalination is not a new technology. The world’s first desalination plant was established in Australia in 1903. There are currently nearly 17,000 desalination plants worldwide, with many of the largest operating in Australia, Israel, Saudi Arabia, and the United Arab Emirates.
Desalination works by heating the salt water and collecting the pure water vapor or pumping salt water through specialized membranes. The leading process for desalination is reverse osmosis, which uses semipermeable membranes and applied pressure to cause water to permeate through the membrane while rejecting salts.
Issues with Desalination
There are some drawbacks to the use of desalination, including:
- Cost: Facilities are costly to build and operate. It has been estimated that a thousand gallons of fresh water from a desalination plant cost the consumer approximately $2.50 to $5.00, compared to $2.00 for non-desalinated water.
- Energy usage: Desalination is an energy-intensive technology; it takes most desalination plants about 3 to 10 kilowatt-hours of energy to produce one cubic meter of fresh water from seawater, compared to traditional drinking water treatment plants that typically use under 1 kilowatt-hour per cubic meter of drinking water.
- Environmental impacts: Sea life can be affected at the intake or inside the plant’s treatment process, and there are issues with disposing of the very salty water that is left after the water is treated.
However, many experts note that innovation, including new technologies and smaller plants, can solve many of these problems, paving the way for the future expansion of desalination. For example, some recent plants are using a new technology known as forward osmosis, which can lengthen the lifespan of the membranes and use less energy. This technology has the potential to be used in smaller plants, resulting in environmental benefits, such as the potential to power these plants with solar or wind energy.
The U.S. Experience
Currently, the U.S. government is doing little to support the use of desalination. The Infrastructure Act of 2021 includes $5 billion for water reclamation and reuse projects, but only $250 million is earmarked for desalination projects.
Most, 68%, of the US desalination plants are in California, Florida, and Texas. Texas currently has more than 100 desalination plants, with the largest in El Paso, producing up to 27.5 million gallons of fresh water per day. Florida has more than 130 desalination plants, with a large plant in Tampa Bay producing 25 million gallons of fresh water per day.
California has 12; the largest is a privately financed plant in Carlsbad completed in 2015 and produces 50 million gallons of desalinated water per day for San Diego County. However, some proposals to build desalination plants face fierce opposition from the NIMBY (Not In My Back Yard) crowd and may never be built. For example, in May 2022, a coastal panel rejected a longstanding proposal to build a desalination plant to produce 50 million gallons of fresh water per day in Huntington Beach due to concerns from environmental groups.
The Israeli Experience
In 1999, the Israeli government started a long-term desalination program that resulted in the building and operating of five desalination plants between 2005 and 2015. They currently have two more plants in development, one aimed to be operational by 2023. Currently, Israel produces about 600 million cubic meters, roughly the amount produced by Texas (434 million gallons/daily), of desalinated seawater annually, accounting for
- approximately 60% of the water provided to households
- 50% of the country’s entire water supply, including for agriculture.
It is estimated that in the near future, desalination will provide 90% of the country’s water supply.
The fact that desalination has provided a safe and reliable water source to Israel, a small desert country, is indisputable. However, widespread use of desalination has also presented public health issues that are only now becoming apparent.
Removal of Essential Elements
Along with salt, desalination removes four essential elements vital to human health: fluoride, calcium, iodine, and magnesium. The removal of two of these elements, fluoride and calcium, is not of concern in Israel because, like in the U.S., fluoride is added to the desalinated water to increase dental health, and calcium is added to prevent pipe corrosion.
Iodine
The human body uses iodine as iodide to make thyroid hormones that control the body’s metabolism and other important processes. Low iodine intake can lead to thyroid dysfunction in adults, and severe iodine deficiency during childhood can harm the brain and central nervous system.
There has been concern in Israel over the last few years about iodine deficiency, which may be partly due to the use of desalinated water. A 2017 study showed that most school-age children and pregnant women in Israel were iodine deficient, falling below the recommended daily intake range. A 2022 study showed that this iodine deficiency is persistent in the school-age population.
Although some have called for adding iodine to desalinated water, most experts believe that a more efficient solution requires using iodized salt instead of regular salt. In Israel, only a very small percentage of table salt is iodized. There is legislation to require iodized salt (currently only recommended) to address the low iodine levels in the population.
This is not a problem in the U.S. because this problem was dealt with in the early part of the 1900s due to the high incidence of goiter (enlargement of the thyroid gland due to iodine deficiency) in parts of the U.S. [1] In the 1920s, iodine deficiency was common across some areas of the country, with one estimate that the prevalence of goiter was as high as 60.7% in certain parts of Michigan. Although not mandated by law, iodine was first added to table salt during this period (check out your box of Morton’s salt), and its usage became widespread. Current estimates are that 90% of Americans currently use iodized salt; goiter and other iodine deficiency problems are very uncommon in the US today.
Magnesium
In Israel, the removal of magnesium with desalination has created more controversy than any other element.
Magnesium is essential for many different processes in the body, including regulating muscle and nerve function, supporting a healthy immune system, helping bones remain strong, helping to adjust blood glucose levels, and aiding in the production of energy and protein.
Magnesium deficiency has been linked with an increase in:
- Heart problems, including high blood pressure, irregular heartbeat, and hardening of the arteries
- Type 2 diabetes
Magnesium is found naturally in many foods, including legumes, nuts, seeds, whole grains, fortified breakfast cereals, milk, yogurt, and green leafy vegetables, such as spinach. The recommended daily magnesium intake is 400-420 milligrams (mg) for men and 310-320 mg for women. It is believed that most Americans receive sufficient magnesium through their food and the use of supplements, such as multivitamins.
In Israel, two studies (here and here) have indicated an increase in deaths and hospitalizations from heart attacks in patients in areas supplied by desalinated water compared to those in non-desalinated water areas. Although not definitive, these results suggest that low magnesium levels may be related to these increases, and the best course of action is controversial. The Israeli government does not recommend adding magnesium to desalinated water due to cost concerns, saying it would raise the cost of water significantly. At the same time, the Health Ministry maintains that adding this element is essential for public health.
Conclusions
There is a rapidly approaching crisis for fresh water in large populous areas in the southwestern US – the federal government restricted the use of Colorado’s water for the first time in 2022. Desalination is a practical and workable solution that is getting little policy attention from the federal government, as demonstrated by the Infrastructure Act, which has earmarked only 5% of its water spending to desalination projects. The public health issues appear to be solvable, but they should be studied now so that they do not delay our nation’s move to greater desalination.
[1] Fun fact. This was especially true in the upper Midwest, where low iodine levels were endemic and were the source of goiter. Two young surgeons made a career out of treating those thyroid problems, Charles and William Mayo. Perhaps you know of their clinic?
Sources
Water Crisis in the West Begins: Colorado River Basin on the Edge of Extinction
Israeli Scientists Fear Public Health Risks from Desalinated Seawater
