The U.S. Central Intelligence Agency recently released a report warning that, within 12 years, almost half of the world’s population will live in countries which are "water stressed.” Water is being pumped from the aquifers of places like Africa, Northern China, South Asia, and the Middle East, faster than it is being replenished. The water table in Northern China is falling at a rate of five feet per year, and in India it is falling from three to 10 feet per year.
Here in the United States, even though we are blessed with an abundance of natural resources, we do have ominous signs of water scarcity. The aquifers that lay underneath the great deserts of the American Southwest are being used up to create electricity for surrounding cities. Rivers like the Colorado are diverted to satisfy the needs of major cities like Phoenix, Los Angeles, and San Diego in California, and the demand is increasing all the time. Various other metropolitan areas, such as Atlanta, Georgia and other fast-growing cities, are seeing water limitation problems, as they begin to compete with the surrounding towns for the wet stuff.
Some water purveyors claim that as much water is used on the town’s landscapes and in various industrial processes, as is consumed in the community’s households. So, not only do these non-residential consumers suck up a whole lot of the wet stuff, but the water, or effluent, they discharge can be rather nasty.
Luckily, technology has been developed to process the effluent, so that it doesn’t earn the name “pollution” wherever it ends up. While the treatment for this used water can vary from community to community, it generally goes through several stages:
1. Primary treatment. This removes solids and organic materials.
2. Secondary treatment. The wastewater enters oxygen reactor tanks, where microorganisms consume the dissolved organics.
3. Tertiary treatment. Chlorine is added to destroy any remaining harmful organisms. Sometimes, sulfur dioxide, which neutralizes the chlorine, is added before the wastewater is discharged.
“There is a public perception issue,” says Jim Kelly, director of operations for Central San in Martinez, California. “That perception being that it’s recycled wastewater.” Central San is the nickname for the Central Contra Costa Sanitary District (CCCSD), which collects and cleans wastewater for residents and businesses in central Contra Costa County.
Most recycled water in the U.S. is very, very close to being pure, but would still need to go through a final phase of purification to become completely safe for human consumption. And, since the great majority of water is used for industrial and irrigation purposes, it is not required to be that pure.
Now, industries that use the water to perform a task, such as cooling equipment, care very little about the purity of recycled water. Contractors, on the other hand, would be wise to take a close look before dousing their clients’ plants and turf. The tiniest components of recycled water can have a significant impact on a landscape.
However, many contractors, unaware of the trace contents of the water, have found it to cause problems. The plant life grows, well… too fast.
“One complaint that I’ve gotten,” says Earle Hartling of the WateReuse Association, “is that some customers have had to hire more gardeners. That’s a big problem.” Hartling is the board member for the California section of the Association, based in Alexandria, Virginia, and is the water recycling coordinator for the Los Angeles County Sanitation Districts. Other irrigators continue to fertilize normally, ignoring the extra nutrients in the water, and end up overdosing their landscapes.
The solution, of course, is to know what you are dealing with when using recycled water for the first time. It is no different than reading the ingredient label on a bag of fertilizer.
Well, there is a difference, actually. That is, normally, if you don’t like the content of the fertilizer, you can switch to a different variety or a different brand. If you have chosen to irrigate with recycled water, there is no turning back; you simply have to deal with what it contains.
Some communities have no choice as to whether or not to use recycled water in the first place. California wrote a mandate into the state water code that stipulates that, if you have reclaimed water available to you, you must use it. Section 13551 of the code “prohibits potable water from being used for non-potable uses, such as landscape, irrigation and industrial use, if recycled water is available at a reasonable cost, is of adequate quality and will not adversely affect the environment and public health.”
As water scarcity becomes a more serious problem in the U.S., more states may follow California’s lead.
This high salinity can take place for various reasons. The cities in the Southwest, for example, have to deal with the problem because of the high TDS (total dissolved solids) of the Colorado River water. But a growing problem is the number of residents that are doing water purification of their own. Self-regenerating water softeners, which use rock salt, infuse a significant amount of sodium chloride into the water. And this is one of the components that is left in the water after the recycling process.
“All that salt goes somewhere,” says Marilyn Smith of the Irvine Ranch Water District (IRWD), “it goes into the sewer system.” Smith is the public affairs manager for the IRWD, located in Irvine, California.
She says that the salinity created by the softeners is not a problem for communities that discharge their water into the ocean. “But if you live in a community where you reuse most of that water like we do here,” she says, “salinity is a very big issue.”
Those trying to irrigate using high-saline water are only going to have trouble in a heavy clay soil, as the sodium tends to bond with the clay and creates something of a clog. Hartling says that normal seasonal rainfall should take care of the situation automatically.
“If you get a salt build-up,” he says, “it’s not really a problem, because the fresh water from the rain will drive that salt out. If you have an average rainy season of, say, 15 inches, that’s fine.”
That is, of course, unless you live in one of the drier portions of the U.S. “If you only get four inches,” Hartling continues, “then you’re in trouble.”
Even in that circumstance, you aren’t dead in the water. The solution, if you have the saline buildup but little or no rain, is gypsum. “What it does,” he says, “is break up the clay that sticks together. It replaces the sodium. It’s not a real expensive material, and you can just water it in, or apply it when you’re aerating the landscape.”
So, if you test the recycled water provided to you by your community, you know what you might have to do to compensate for the trace elements within the water.
Purple is the universal color for recycled water. Recycled lines are clearly marked so that there’s never any confusion as to which is which. PVC pipe that is used will either have a purple stripe down the length or the entire pipe will be purple. There are now purple valve boxes, or at least purple lids, purple fittings, even purple valves. So when you see purple pipes alongside white pipes, you can easily identify which line is carrying reclaimed water.
Even though the quality of the recycled water may be quite safe, communities take extra steps to protect homeowners from any potential health risks. Frequently, for example, landscape irrigators using recycled water for spraying must keep the watering times limited to those that have the least chance of contact with the general public.
If you intend to use recycled water, the wisest action is to consult your community’s water district and request their usage guidelines.JUNE 04