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Student Life

Itchy skin, stiff clothes, dishwasher residue? Hard water explained

Have you ever waited two hours for the dishwasher to end, only to pull them out and they look as if they were covered in Elmer’s Glue? Showered and had dry itchy skin? Pulled clothes out of the dryer, only to find that they are stiff, hard and itchy?

For most students, the former may be more noticeable than the latter. With a number of things on a students’ to-do list, hand washing a large load of dishes can take a chunk of time out of an already crammed schedule.

But for Raquel Rhoades, a history major at the University of South Florida, that’s where the dishwasher comes in. After moving into 4050 Lofts apartments, she noticed a chalky appearance on the dishes and silverware when washing them by hand, which was much worse when using the dishwasher.

Actually, what she did not know is that it’s scum, the reaction of detergents mixing with the hard water from her faucet. But what exactly is hard water? The Digital Bullpen went in search of an answer.

“Hardness refers to the presence of certain mineral ions in the water,” said Dr. Jeffrey Cunningham, Assistant Professor in the Department of Civil and Environmental Engineering at USF. “The two that are most responsible for hardness are calcium and magnesium, and water with less calcium and magnesium are soft.”

Rhoades noted that on a trip to Tennessee she did not notice the problem, and in her home town of Jacksonville it’s not a problem either. This is because water in Florida is very hard compared to other states across the country. It also differs within the state from city-to-city.

According to the U.S. Geological survey,  the softest waters are in parts of New England; the South Atlantic-Gulf States, such as Alabama, Georgia, South Carolina and North Carolina; the Pacific Northwest, such as Oregon and Washington;  and Hawaii. Moderately hard waters are common in many rivers of Alaska and Tennessee. Very hard waters were found in areas of Texas, New Mexico, Kansas, Arizona and Florida.

Click here to see the accompanying map.

Cunningham explained that most places pull their water from the ground. The hard water is caused by the fact that some states, including Florida sit on a lot of limestone, which is made of calcium carbonate.

So if your water source is groundwater, as it is in Florida,  it has a lot of calcium in it, causing hard water. But what about the differences within state lines?

Doug Calman, the librarian specialist at the Florida Geological survey, said the Floridan aquifer supplies water to the state. The aquifer’s water yields a hardness of no more than 180 ppm (the unit of measure for hard water). The northern part, which includes Tallahassee, is less than 20 ppm. In the rest of the state, including areas such as Tampa and Orlando through Miami, the ground water has more than 180 ppm making the water hard. This explains why Rhoades doesn’t have the problem at home in Jacksonville.

Click here to see the accompanying map.

Softening the water is based upon personal preference, said Cunningham. Accordingly, what you may want to do first is to test its hardness.

“There are a couple different chemical processes that you can use to soften water. On a big scale, what’s often used is lime softening,” said Cunningham. “You add a chemical called lime, not the fruit. It’s a compound that raises the ph of the water making it more basic. At high ph conditions you would precipitate out the calcium and magnesium causing hardness.”

He explained that “precipitated out” means you have a calcium mineral that is dissolved in water. In water the calcium has an ionic charge of plus two. When the dissolved calcium ion reacts with something like carbonate, which has a minus two charge, then those ions will together form to change from a dissolved form into a solid form, which can then be measured.

A representative at Aqua Systems, a water softening company on North Florida Avenue in Tampa, who did not want to share his name; said that most water softening systems using the precipitation process of “ion exchange” costs about $500 to $2000, depending on the amount of resin minerals in a certain water conditioning system

“It’s like comparing apples to apples and you gotta do your homework,” said the Aqua Systems representative “You may add about a pound at one place for a cheap one, but then you’ll get more maintenance costs. Those may need to be regenerated with more resin every few days. An expensive one might could go for about a year.”

He said some people “hate the hard water, some people take it with a grain of salt.”

While it isn’t a health hazard, for some it can be a nuisance in anyone’s home, said Cunningham.


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