Water Treatment 

The City of Siloam Springs gets our water from the Illinois River in Oklahoma. The water is treated in a conventional water treatment facility. There are three reservoirs located north of the facility that store water for supplemental use.

Clean water is our most precious natural resource. Please contact the City's Water Division at (479) 238-0921 for more information. 

Aerial view of the Water Treatment Plant


Disinfection of the water supply is accomplished by chlorination. Water leaving the treatment plants contains approximately 1.5 milligrams per liter (mg/L) of free residual chlorine. The free chlorine residual continues to disinfect the water in the distribution system. Trihalomethanes, by-products of chlorination, are regulated by both the State of Arkansas Department of Health and the Environmental Protection Agency (EPA). Compliance testing for THMs in the distribution system is performed quarterly, utilizing approved EPA methods. Siloam Springs maintains THM levels which are below the maximum contaminant level (MCL), as established by the EPA. The MCL for THMs is currently 80 parts per billion (ppb).

Presently, chlorination is the most widely-used method of disinfection in the water treatment industry. Research for alternative methods has produced effective disinfection techniques, but these methods produce disinfection by-products of their own.


The City of Siloam Springs services approximately 18,000 people and is therefore required by the EPA to submit 20 bacteriological tests per month on the system water to the State of Arkansas Department of Health. Bacterial quality criteria for finished drinking water from public supplies is based on the presence or absence of total coliform, as stated in the Arkansas Total Coliform Rule.

The Water Plant Staff performs bacteriological analysis for coliform daily, implementing EPA-approved methods.

Testing is performed on treated water prior to entry into the distribution system and on water from representative sampling locations throughout the distribution system.

 The City of Siloam Springs consistently meets standards established for bacteriology.


In Siloam Springs, the naturally occurring fluoride in source waters is approximately 0.3 mg/L, This is supplemented to provide a finished water concentration for fluoride at 0.7 mg/L. This is considered the optimum level of fluoridation most effective for prevention of dental cavities in children up to their early teens. Research by the American Dental Association has found that fluoridation preserves integrity of teeth into adulthood.

Supplementing the fluoride produces water considerably below the current EPA-established MCL of 4.0 mg/L. For additional information on fluoridation, contact the American Dental Association or seek advice from your dentist.

Lead & Copper

In the 1991 Lead and Copper Rule, the EPA required all public water systems to monitor lead and copper at residential taps. As a large water system serving greater than 14,000 people, Siloam Springs is required to collect 30 lead and copper tap samples every three years. In compliance with these changes, Siloam Springs collects and monitors samples every three years from 30 homes built before 1986. The testing is done only in homes built these years because the EPA has determined they are the most likely to contain lead pipes, lead solder, or copper pipes that have not yet "weathered" (acquired a protective mineral coating inside the pipes). If your home was built in these years and you would like to participate in this testing program please contact us. Testing is the only way to determine if lead or copper are present.

Water coming into contact with lead pipes, copper pipes with lead solder, or other leaded materials may contribute to lead and copper in the drinking water. After an extended time of contact with consumer plumbing, lead and copper may leach from plumbing materials into the drinking water. Drinking water is regularly tested at households in the City and is found to contain less than 0.005 parts per million (ppm) lead and less than 0.50 ppm copper. Therefore, the lead/copper levels in consumer taps originate from home plumbing and not from municipal water systems.

Residents in Siloam Springs concerned about lead or copper can take the following precautions to minimize leaching from their home plumbing:

  • Flush the water used for cooking and drinking from each cold water tap after the water has been standing in contact with your home plumbing for more than six hours (for example, overnight or during your workday). Flushing a tap for 1-2 minutes will insure that the water is representative of the water from the distribution mains and not from residential plumbing. Flushing is important because the longer water is exposed to the lead pipes or lead solder the greater the possibility of lead contamination. The flushed water can be collected and used for cleaning, on houseplants and gardens.
  • Never cook with or consume water from the hot water tap. Hot water dissolves lead more quickly than cold water. Use only water from the cold tap that has been thoroughly flushed for consumption.

The City of Siloam Springs established a ban on the use of lead solder and lead pipes for construction in May of 1988. If you are planning to re-plumb your house or have any plumbing repaired, it is your responsibility to insure the use of low-lead materials as required by this new law. Other environmental sources of lead are:

  • leaded paint
  • leaded gasoline
  • lead-contaminated dust/soil
  • ceramic pitchers or plates with lead-based glazes
  • leaded crystal
  • lead soldered seams of certain canned foods (acidic foods are especially susceptible to lead contamination)
  • brass and chrome-plated faucet fixtures