Today, water treatment is more important than ever. According to the United States Environmental Protection Agency (U.S. EPA), approximately one fifth of all United States water sources are potentially tainted. The National Academy of Sciences issued an extensive water quality study where two important facts were discovered. First, up to 45 million Americans have been exposed to potentially unsafe water in recent years. Second, up to 10 percent of community water systems are found to be in violation of important public health standards in any given year. Nearly 3,000 jurisdictions are facing water quality problems equal to far worse than Flint, Mich.
Let’s first look at how water becomes contaminated. Water is affected by minerals, gases, and vegetation found in nature, microorganisms that need water to survive, and byproducts from man-made agricultural and industrial processes. Let’s start with the atmosphere. 70 percent of all precipitation returns quickly to the atmosphere, while 30 percent of all precipitation seeps down into the ground or becomes part of oceans, rivers, and lakes. When water percolates into the ground, it loses some of the impurities it absorbed from the air and on the ground. But while the soil structure filters out certain impurities, it provides ample opportunity for water to dissolve large amounts of earth minerals, which may increase its hardness and iron content, among other things. The atmosphere itself may also play a role in water quality. Carbon dioxide and oxygen enter the water from the atmosphere – carbon dioxide can unite with water to form carbonic acid. In vegetated areas, oxygen in water is consumed and carbon dioxide is increased through decay of vegetation. In limestone areas, the water containing carbonic acid reacts with limestone and becomes hard – calcium and magnesium bicarbonates are formed.
Life forms also play roles in water quality. Microorganisms are extremely small animal or vegetable organisms. Most of the organisms in water are harmless – bacteria, protozoa, and fungi that purify polluted water are essential to our well-being. Unfortunately, some microorganisms are the sources of disease. The potential disease-producers are found among five of the subgroups of living organisms in water: bacteria, protozoa, worms, viruses, and fungi. They can cause commonly known diseases like dysentery, cholera, and hepatitis, among others. Where there is even a possibility that water contains pathogenic organisms, that supply must be considered contaminated. Testing and analysis of the water by a certified laboratory is the only way of determining the presence or absence of microorganisms.
Man-made issues include waste from humans, farm animals, and industrial processes. They contribute contaminants to the surface water supply that can eventually affect groundwater. Industrial processes may discharge excess carbon dioxide into the air, and chemicals, such as pesticides, detergents and cleaning agents, may be added to the local water supply through industrial discharge or disposal of household chemicals.
The testing of water quality is critical. Drinking water contaminants can be divided into two groups, based upon US EPA regulations: primary or secondary. Primary contaminants have adverse effects on public health. Water samples are sent to a lab for chemical or microbiological analysis. Secondary contaminants affect the aesthetic qualities of water, such as taste, odor, hardness, and color. Field testing may be used for secondary contaminants. Water should be analyzed prior to making any treatment recommendations. The 2018 Uniform Plumbing Code®, Section 609.9, states, “New or repaired potable water systems shall be disinfected prior to use where required by the Authority Having Jurisdiction. The method to be followed shall be that prescribed by the Health Authority.”
Water tests can be conducted in both the field and in a laboratory setting. However, there are some contaminants that must be tested in the field and others that must be tested in a lab. Tests should be conducted in the field when the symptom or contaminant may dissipate before a water sample can reach a lab for testing. An example of this might be testing for foul odor. Again, it is important to remember that water, which may have primary contaminants, must be tested in a lab. Certain precautions must be observed in preparing a water sample for shipment to a laboratory. Testing laboratories furnish clean sample bottles and sampling instructions – careless handling of a sample can produce misleading results.
Tests for the presence and concentration of the following contaminants in a water sample can be conducted in the field:
- Chlorine
- Arsenic
- Nitrate
- Lead and Copper
- Hardness
- Iron
- Manganese
- Hydrogen Sulfide
- Tannins Alkalinity
- Total Dissolved Solids
- Dissolved Oxygen
Now that I have probably scared you from getting a glass of water, there are common treatments that can provide safe, good tasting water. Simple filtration will remove suspended solids; aeration removes gases and adds oxygen; reverse osmosis systems removes undesirable materials; disinfection removes or inactivates disease causing microorganisms; ion exchange, probably the most common treatment, improves drinking water, softens hard water, and removes iron. These are just a few of the many options available.
What I have experienced as the most common treatment is the point of entry water softener (i.e. ion exchange). In order to provide a successful point of entry treatment system, certain things need to be considered.
- Efficiently process water with a capacity that meets the flow rate requirements imposed by the building demand
- Avoid introducing an excessive pressure drop
- Be sufficiently cleaned by the flow rate available in the distribution system
- Fit in the available physical space
- Determine what water lines will be treated – hot water lines, partial cold water, or the entire system
- Add up the total water supply fixture units (WSFU) for the fixtures using treated water
- Convert WSFU to flow rate in GPM. Next, one will select the appropriate system size from the manufacturer’s tables based on the flow rate and the needed treatment capacity
At this point, it is important to remember certain requirements. One is the plumbing code – water sizing requirements that ensure that the fixtures and appliances work properly. Secondly, we need to consider the size of the treatment to ensure that the water is being treated as planned.
The 2018 Uniform Plumbing Code®>, Section 610.2, states the following dealing with pressure loss:
“Where a water filter, water softener, backflow prevention device, tankless water heater, or similar device is installed in a water supply line, the pressure loss through such devices shall be included in the pressure loss calculations of the system, and the water supply pipe and meter shall be adequately sized to provide for such a pressure loss. No water filter, water softener, backflow protection device, or similar device regulated by this code shall be installed in a potable water supply piping where the installation of such device produces an excessive pressure drop in such water supply piping. In the absence of specific pressure drop information, the diameter of the inlet or outlet of such device or its connecting piping shall be not less than the diameter of such water distribution piping to the fixtures served by the device. Such devices shall be of a type approved by the Authority Having Jurisdiction and shall be tested for flow rating and pressure loss by an approved laboratory or recognized testing agency to standards consistent with the intent of this chapter.”
Section 608.1 also states the following:
“Where the water pressure in the main or other source of supply will not provide a residual water pressure of not less than 15 pounds force per square inch (psi) (103 kPa), after allowing for friction and other pressure losses, a tank and a pump or other means that will provide said 15 psi (103 kPa) pressure shall be installed. Where fixtures, fixture fittings, or both are installed that, require residual pressure exceeding 15 psi, that minimum residual pressure shall be provided.”
In order to meet both the plumbing water pipe sizing pressure requirements while still maintaining properly treated water, there are several considerations. The following is needed to determine the proper tank-type treatment (common ion exchange water softener):
- Determine flow rate and water usage requirements for the product water
- Peak water demand times and their effects on required processing rates
- Availability of regeneration windows
- Water volume
- Available pressure and flow rate in the plumbing distribution system
- Time needed for complete interaction between media and contaminants
- Treatment capacity of the water treatment system.
In certain residential applications, the installer may also have to consider if there is adequate water supply for backwashing and whether the water needs to be continuously treated. Based on these considerations, multiple tanks may be required.
Today, there are many issues with several water sources and it remains a growing problem. Technology is available to treat the water and remove the harmful or unpleasant contaminants – when the job is completed, the end user should be supplied with clean, safe drinking water that meets all plumbing code requirements.
