DES MOINES, Iowa — A ban on lawn watering across the Central Iowa Water Works system is staying in place.

Staff said conservation efforts over the weekend helped to keep nitrate levels in drinking water within the Environmental Protection Agency’s limits. River conditions are also improving. Tests on Monday showed nitrate levels in the Des Moines and Raccoon Rivers were down roughly 10% since Saturday.

“As a result of high nitrate concentrations in the rivers – the Des Moines River is at 15.6 mg/L and the Raccoon River is at 15.3 mg/L – the lawn watering ban will remain in effect,” said a Des Moines Water Works spokesperson via email.

Though lower, levels are still well above the Federal standard for drinking water. The process of filtering it is not only critical, but complicated. When the water gets that contaminated, it has to go through an advanced treatment process, according to CIWW. That means lower production of processed water.

While the EPA nitrate limit is 10 milligrams per liter, one water quality expert said the EPA safe limit was established more than fifty years ago in 1974 to protect babies whose formula was being mixed with water, and may be outdated.

“Since then, we know that levels below ten parts per million consumed over a lifetime have health consequences for adults,” said Chris Jones. “There’s associations between nitrate in water, three parts per million and above, with thyroid cancer, colorectal cancer, birth defects, and some other things, bladder cancer in women. And so clearly, drinking high-nitrate water for an adult over a lifetime presents health risks.

Jones is a retired research engineer from the University of Iowa and a former lab supervisor at Water Works. He said he was confident in the ability of its staff to treat the water. He is now on the board of the Iowa Driftless Water Defenders, a non-profit organization that works to protect water resources in northeast Iowa.

“So, just getting below the ten parts per million, sure, it’s meeting the EPA standard, maximum standard, but that doesn’t necessarily mean that there’s not a problem,” he told WHO 13’s Katie Kaplan.

Jones said there are ways people can protect themselves at home, like by installing an RO, or Reverse Osmosis, water filter. Jones said there is no risk from bathing in contaminated water, but you don’t want to ingest it. So you only really need such a system installed in your kitchen, not necessarily the entire home.

The product could set you back $1,400 professionally installed and ready to go, according to TJ Riley, owner of Aqua Systems of Des Moines. Riley said his business has been booming since the local situation developed recently.

To get updates on the lawn watering ban, you can check the Central Iowa Water Works Facebook page. To learn more about nitrate in Iowa’s drinking water, you can read “Nitrate in Drinking Water: A Public Health Concern for All Iowans,” by the non-profit Iowa Environmental Council (IEC).