Insight: Public drinking water systems

** Editor’s note – This is the latest installment in an ongoing series highlighting how systems, programs and public entities which we rely on every day operate. 

The tap water in local municipalities goes through a relatively simple process on it’s journey from the underground water table to faucets and yard hydrants throughout the city.

Municipal water treatment often begins with the water being pumped from sizable wells. For instance, in the case of Farmington the city relies on 14 well houses throughout the city. The pump systems, as well as the buildings that contain them, vary in size based on the amount of water that well produces. A mid-sized well and treatment facility is capable of treating around 175 gallons of water per minute.

While some municipalities rely on lakes or rivers for the starting point of their potable water system, all communities in the immediate area rely on wells for drinking water.

According to Casey Barnhouse of Farmignton’s water and sewer department, the city began treating their water with a Water Remediation Technology (WRT) system in 2011.

The WRT system removes harmful contaminants, such as radium, from the groundwater sourced by the wells. Radium is a type of radionuclide in the alkaline earth metal class of elements. It’s picked up by the water as it seeps through rock and soil on its way down to the water table.

After being pumped up from underground, the water enters the city’s system and goes through the first phase of treatment. The water passes through “inlet bags” that filter out larger debris and sediment into cylindrical containers.

The water then flows through the second stage filtration tanks which contain WRT’s proprietary treatment media. The tanks work much like small filters that connect to a household faucet. But these large filters require special crews to come in about twice a year to clean out all of the captured material and install new media.

After going through the large filtration tanks, the water passes through the last filters know as “outlet bags.” This filter out anything remaining including media from the large tanks that may have washed through.

The water is then chlorinated with 12.5 percent sodium hypochlorite before being directed into the city’s potable water network. Each well house will either pump it’s treated water directly into the water system or to a nearby water tower to be stored and used as city consumption increases during peak usage times.

The system is electronically monitored and alerts utility workers when high levels of contaminants or low levels or treatment chemicals are detected that fall outside parameters set by the Missouri Department of Natural Resources (DNR).

In the past, before DNR put in place the filtration standards they have today, water was often pumped directly from the many wells around town directly into the potable water network.

However, DNR studies have shown that portions of the area’s water table contain miniscule radioactive particles, referred to as radionuclides, and heavy minerals that are unsafe for consumption in large quantities.

Consumption of heavy minerals, such as lead, can pose long-term health risks and must be filtered out of public drinking water systems.

Farmington Public Works Director Larry Lacy explained that since the current system was installed eight years ago, some area residents have complained about the change in the taste of the water. Lacy said in most cases, any undesirable taste can be eliminated from the water simply by attaching a charcoal filter to your water faucet.

Treating the water on site is not only efficient but cost-effective as it eliminates the need for large amounts of energy to pump water to and from designated treatment facilities.

Although the treatment systems have electronic safeguards and monitoring devices built into the lines, the system still requires utility workers to check the processes daily as mechanical failures can occur.

“Every now and then something will come apart in the system,” explained Lacy. “One of our well houses had a break in the line underneath the foundation … it broke through the foundation and sprayed water up, ruining the ceiling.”

The pumps require ongoing maintenance and monitoring. Lacy stressed the importance of constant monitoring, saying, “Public health is just so important that you just can’t leave it alone.”

If something were to happen to cause the entire system to fail or shut down, the city has enough water reserves to last for two days. The amount of reserve water required by regulations is one day.

“As far as water systems go, [Farmington’s] is pretty straight forward,” Lacy explained. 

The inlet and outlet filters are crucial to the water treatment process. A pump sits just to the side of a series of filters, compensating for the pressure differential between the lines and large filter tanks.  

The final stage of treatment is where the water is chlorinated with 12.5 percent sodium hypochlorite before being released into the city’s tap water system.

Bobby Radford is a reporter for the Daily Journal. He can be reached at 573-518-3628, or at bradford@dailyjournalonline.com.