The U.S. Environmental Protection Agency’s (EPA) Water Infrastructure Resiliency and Finance Center, in collaboration with the...
Evaluating source water to determine proper treatment
Water treatment has evolved greatly over the past several years, from simple filters and water softeners to more complex treatment including new and different media, reverse osmosis, ultrafiltration and nanofiltration. A major reason behind this move forward is that more water testing is being done throughout the U.S. by public water systems, in addition to studies by the U.S. Geological Survey that map common contaminants in groundwater and surface waters such as lakes and streams.
More and more contaminants are being tested at lower levels as technology advances. This means the industry is seeing more contaminants at varying levels, which can be treated through various methods. Before treating water, however, it is more important than ever to test the water first to determine the best course of action for potential customers. Following are some questions to help determine which tests to run.
Groundwater from springs and wells can be prone to high mineral and radiological levels, as these are dissolved by water as it moves through geological formations. For groundwater coming from a private well, consider the well depth and geological formations in the area. Deeper wells can produce water with a much higher mineral content.
Iron- and sulfate-reducing bacteria are common problems in well water, and present themselves in obvious ways, including the presence of a slimy biofilm usually found in the backs of toilet tanks and sometimes in filters or water treatment tanks. Tannins typically are a problem in shallow wells, causing discoloration ranging from a faint yellow to a darker tea color.
Surface water sources include lakes, rivers, streams, ponds and reservoirs. The biggest contaminants of concern with these sources are microbiological, given that they are open to possible animal contact. Most surface water sources are public water supplies, for which municipal water systems provide disinfection to reduce microbiological contaminants. Surface water also is susceptible to contamination from runoff pollutants, including pesticides, herbicides, gasoline and road salts.
Rainwater is more frequently being used as a source of drinking water. Like surface water, rainwater is open to the atmosphere and prone to microbiological contamination, so disinfection is necessary. Also consider the material that may come in contact with the rainwater prior to storage or use—this typically includes roofing materials. Because rain comes from the atmosphere, it also is prone to airborne contaminants. These airborne contaminants include radiologicals such as cesium and iodine, which come from sources such as the 2011 Fukushima Daiichi nuclear disaster in Japan.
Determining the source of water can lead to further questions, including the following.
If the source is groundwater, does it come from a private well or a spring? If it is a spring, is it developed or undeveloped? What is the spring’s approximate flow rate? Where is the spring located? Is there agricultural or industrial activity nearby?
If the source is a private well, how deep is it? How old is it? What is the flow rate? Are there any aesthetic issues, such as laundry staining, scale buildup, or staining of fixtures, sinks and tubs? What color is the staining? Are there odors? Where is the well located? What kind of septic system is in use? Where is the septic tank located? What else is nearby? Are there any golf courses, farms, animal lots, gas stations or other industries in the vicinity?
It is a good idea to research the geology in the area to see what naturally occurring contaminants may be present, such as arsenic, radon, radium or uranium.
If the source is municipal water that is from a groundwater source or even a surface water source, locate a copy of the annual water quality report. This report will give you an idea of the water quality and treatment processes the municipality uses, including disinfection methods. If you know which type of disinfection is employed, you can look for the pertinent disinfection byproducts. Many water supplies are now putting this information online, making it easier to locate. Additional information, including the monitoring schedule, will give you an idea of how often contaminant levels are checked.
It is common to ask how many people live in a home in order to size equipment. How often do you ask about the health and ages of those living in the household? Young children and the elderly can be more susceptible to certain contaminants, including bacteria and nitrates, which are common in well water. Those with serious health issues, including cancer, HIV and organ transplants, need a higher level of quality when it comes to water. They need to be assured the water has no chance of microbial contaminants, so additional point-of-entry and/or point-of-use disinfection is often necessary.
Learning about the source of the water gives an idea of possible contaminants. Learning more about the individuals in the household and their health conditions will provide more information about the homeowners’ expectations when it comes to the safety of their drinking water source. Knowing the homeowners’ safety concerns allows treatment professionals to present all of the options available, thus providing a total water treatment system that not only treats the obvious aesthetic issues, but also treats those that present health risks.