Bad Septic System Can Poison Wells


Most Star Valley residents get their water from a well, flush their toilets into to a septic system and have never tested their groundwater.

That’s a potentially toxic combination, especially if a septic system is within 100 feet of a well or starts to leak. In that case, it could deposit waterborne pathogens and fecal matter into the groundwater.

Because residents are not required to test their well water, “they could be drinking themselves to death and not even know it,” said Vern Leis, chairman of the Water and Sewer Commission.

The Star Valley Water and Sewer Commission received these startling revelations last week at a meeting.

Kristine Uhlman, with the University of Arizona Water Resource Research Center, offered these grave prediction’s, but said things can be done to prevent contamination.

These include testing groundwater, installing water filters and well caps and avoiding dumping contaminants above ground where they could seep into the water supply.

Currently in Arizona, 100,000 domestic use wells provide water to 120,000 households.

In Star Valley, an estimated 755 parcels are hooked to private wells or about 69 percent of the population. In addition, 955 parcels deposit their waste in a septic system.

So many wells make contamination inevitable.

Nationwide, 79 percent of wells contain one or more contaminants harmful to human health, according to the U.S. Geological Survey.

Additionally, 90 percent of wells in Arizona exceed at least one contaminant standard, including an excess of nitrates, arsenic or radon.

Most well owners, however, don’t know if their wells are contaminated because they don’t have to test it.

Uhlman suggested the town consider testing some of the wells to check for problems. Although the town cannot force residents to comply, they could ask residents to participate in a study and help pay for testing.

“The potential (of contamination) is very, very great because of our aquifer and its short recharge,” Leis said. “No, we don’t know (for sure) because no one monitors from a water quality standpoint but Brooke Utilities.”

Even without testing, residents can help keep wells safe by following a few simple guidelines.

The first is to keep dirt and debris clear of the well. Install a well cap, which covers the opening surface so contaminants do not enter. If an animal frequently uses this area as a bathroom, Uhlman said this waste could eventually enter the water supply. Residents should clear the area around the well aprons to prevent this.

“Stored pesticides, lawn additives, oil and grease, and failing septic systems are the most likely source of domestic water supply pollution,” according to the Arizona Well Owner’s Guide to Water Supply.

For this reason, homeowners must avoid spilling gas, oil or pesticides on the ground. Eventually, these contaminants seep into the water supply. Because Star Valley sits on consolidated aquifer material of granite, water moves slowly through fissures and cracks, but it does eventually enter the water supply.

Water in Star Valley can move through the ground at a maximum speed of 300 feet a day. This means something dumped within 300 feet of a well could enter the water supply by the end of the day, Uhlman said.

Gas stations, repair shops and mining activities all have the potential to release contaminants into the groundwater.

Consequently, in some communities, zoning ordinances keep these facilities away from groundwater supply areas.

Water and sewer committee members asked how they could establish ordinances when the whole town sits on top of the water supply. Uhlman said it probably couldn’t.

Finally, residents can educate themselves on proper maintenance. A free copy of Uhlman’s book, Arizona Well Owner’s Guide to Water Supply, is available at Star Valley Town Hall.

“We could have contamination all over and not know it,” Leis said.

“We need to find out what we have and how bad it is.”

Leis said he is working with Uhlman to set up instructional classes for residents.


Sara Kuzma 7 years, 2 months ago

Water testing is important to do every year, especially if you have a septic system and a private well! A good website for water testing information is


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