Tom Holm and I presented the results from our study of arsenic in groundwater in the Tolono area at a public meeting this past Tuesday (October 4). The crowd was small but very interested in the topic, and asked a lot of good questions. In this post I thought Id post some of what Tom talked about regarding options for dealing with elevated arsenic in well water.
Tom’s and my powerpoint presentations can be found on the Water Survey website. The Illinois Public Health Department has prepared a fact sheet on arsenic.
As I mentioned in my previous post, there are two aquifers in the Tolono area, the Glasford and Pearl Aquifers. The Pearl, which was found to have the highest levels of arsenic, is deeper than the Glasford, at depths around 160 – 190 feet below the surface. Because these aquifers are laterally discontinuous, there are limited options as far as drilling a new well to replace a well contaminated with arsenic. When wells are completed in the Pearl Aquifer, it usually means that the Glasford Aquifer is not encountered at that location. (For example, if you look at the last slide in my presentation, a well log for one of the contaminated wells indicates no Glasford Aquifer at this location.) There are no aquifers deeper than the Pearl in this area.
A shallower bored well could be installed, but these types of wells have their own issues. They are large diameter wells not completed in an aquifer, but basically collect water percolating down from the surface, almost like a cistern. Because of this, these wells can be contaminated with surface contaminants, such as fertilizers and pesticides. A Water Survey study a few years back showed these wells are much more likely to be contaminated than drilled wells. They also often go dry during droughts.
Some people who have well water with quality problems use bottled water for drinking and cooking. Depending on how much water you use, this may be an economically viable option.
Some of those in the neighborhood southwest of Tolono with the very elevated arsenic concentrations have hooked up to Illinois American water from the Mahomet Aquifer. They were fortunate in that a water line runs down their road, making the cost of a hook-up practical. This option might be prohibitively expensive for people who don’t live near a water line.
Treatment is certainly a viable option, with reverse osmosis (RO) being the most favored technology. It’s a mature technology, and the price is generally reasonable. The unit fits under the sink, with a dedicated faucet for drinking and cooking. You wouldn’t want to run all your water through a reverse osmosis unit, the maintenance costs would skyrocket. Arsenic toxicity is through ingestion, and bathing, washing dishes, etc., with arsenic at the levels we see in Illinois is not a health concern. Reverse osmosis still requires that a water softener be used, otherwise the unit won’t function efficiently. And periodic maintenance needs to be done. RO units can be bought or rented. A photo of one is shown below:
