Water Quality and Common Problems
If we think back to our school days, most of us can remember studying the “hydrological cycle”. You remember the process of how water vapor condenses in the atmosphere and falls to earth as precipitation. Once on the surface of the earth, most of the water evaporates back into the atmosphere, where it will again condense and fall back to earth as precipitation. About 30% of the precipitation, however, does not evaporate. Instead, it seeps into the ground or runs off into streams, rivers, or lakes. As the water seeps into the ground or as it flows over the surface, it dissolves minerals and other substances contained in the ground. Under the surface, the water tends to collect in porous portions called ‘aquifers.’ These aquifers are the source of our well water.
Points To Keep In Mind
- Water as found in nature, will always have some substances dissolved in it.
- It will always have the potential to have particles suspended in it.
- It will always have the potential to be a suitable home to disease causing organisms.
This is true of “fresh” mountain streams, well water, and even municipally treated water systems. To achieve “pure water”, or anything close to that goal, water must be filtered or treated in some way.
As you begin to see, the problem for us to solve will depend upon what the water has had contact with. These conditions can vary greatly, not only from one region of the country to another, but also within the same general location. Water drawn from wells in the same area may not be exactly the same. The quality of water from a municipality owned treatment facility will depend upon the age and condition of the equipment. Even though the water may be classified as safe to drink, the aesthetic quality may be less than desirable.
Fortunately, our knowledge of the nature of water has increased steadily over the years. The most frequently occurring problems have been studied very closely. We now know the symptoms, the cause of the symptoms, and how to cure the problem itself. Sometimes the symptoms are easy to read and easy to cure. Other times, several problems exist in the water at the same time. Then it gets more complicated, and usually more costly to correct.
Let’s examine these water problems as they will be reported to you by your customers … the symptoms they see, taste, smell or fear. Along with the symptoms we will provide the cause of the condition, so you will be able to explain to our customer exactly what is going on with their water supply.
Common Water Problems
HARDNESS (Calcium and Magnesium)
The term hardness refers to the quantity of dissolved calcium and magnesium in water. These minerals, which come primarily from limestone type rock formations, are found to some degree in almost all natural waters. Calcium and magnesium cause problems for two principal reasons:
- When the water is warmed, they precipitate out of solution and form a hard, rock-like scale. This scale accelerates corrosion, restricts flow, and reduces heat transfer in water heaters and boilers.
- When they combine with soap, they react to form a curd, which interferes with cleaning, dries out skin, and leaves deposits on plumbing and clothes (bathtub ring; ring around the collar).
Waters which naturally contain very little hardness can also be problematic because they may be corrosive in some applications (such as acidity).
For some applications, sequestering agents (Siliphos) are good for hardness conditions under 15 gpg. The only practical method for hardness removal above 15 gpg in residential applications is through cation exchange process employed by water softeners (also called conditioners).
Water which contains excess acidity tends to act aggressively towards plumbing and fixtures, causing corrosion and staining (i.e.-blue green stains on fixtures from copper pipes). Relative acidity/alkalinity is measured on the pH scale, ranging from 0- 1 4, where 7 is neutral, numbers lower than 7 are progressively more acidic, and numbers higher than seven are increasingly alkaline (basic). The pH value refers not to the quantity of acidity, but rather to the relative acidity/alkalinity of a particular sample.
Alkalinity acts as a buffer to deactivate the acidity, a process called neutralization. For example, limestone (calcium carbonate) is often applied to soil to offset the acidity which comes from acid rain and decaying organic material. The acceptable range for water is 6.5-8.5.
Acidity cannot be removed from water. However, it can be neutralized by raising the pH with alkalinity. This can be done by injecting a highly basic (alkaline) solution with a feed pump or by passing the water through a bed of processed limestone or similar material.
The presence of Iron is a very common water quality problem, particularly in water from deep wells. Water containing even a significant quantity of iron may appear clear when drawn, but will rapidly turn red upon exposure to air. This process is called oxidation, and involves the conversion of ferrous (dissolved) iron, which is highly soluble, to ferric (precipitated) iron, which is largely insoluble. The ferric iron then causes red/brown staining on clothes, fixtures, etc.
Iron concentration is measured in ppm or mg/l (milligrams per liter, where 1 ppm = 1 mg/l). Staining usually becomes a problem at concentrations greater than 0.3 ppm. Removal is through ion exchange (water softener) or oxidation/filtration (APIR).
Manganese is a metal similar to iron which causes a grey/black stain. It can cause staining in concentrations as low as 0.05 ppm. Manganese is removed in a manner similar to iron, although oxidation is more difficult, requiring a pH of at least 8.5.
Hydrogen Sulphide (H2S)
Hydrogen Sulphide is a gas which smells strongly like rotten eggs. It results from the decay of organic matter with organic sulphur and the presence of certain types of bacteria. Even very low concentrations are offensive as well as highly corrosive (silver tarnishes almost immediately upon contact with H2S).
Because it is in a gaseous form, H2S cannot be collected in a sample bottle for laboratory analysis. Therefore, its presence must be reported when a sample is submitted for a treatment recommendation. It can be removed by oxidation/filtration, aeration, or well sanitization.
Turbidity is a measure of suspended particles in water and can range from large particles which settle out of solution rapidly (such as sand), to extremely fine sediment which may stay suspended in solution even after standing for hours. Treatment depends upon size, which is measured in microns.
Tastes and Odors
Most tastes and odours are caused by the presence of organic matter and chlorine. The vast majority of these can be removed with activated carbon.
Organic Chemical Contaminants
The presence of toxic chemicals at various concentrations has been widely documented in many water supplies. Detection can be difficult as these contaminants often have no taste or odour. Treatment depends on type and concentration. These chemicals may be industrial solvents or agricultural pesticides and herbicides. One of the most common is Trihalomethane (THM) which is formed when chlorine in the water reacts with natural organic matter.
Total Dissolved Solids (TDS)
TDS is the sum of the mineral salts in water and if too high can result in objectionable taste, cloudy ice, interference with the flavor of foods and beverages and scale left behind in cookware. Generally speaking, the lower the TDS the more acceptable the drinking water. TDS of 1,000 ppm or more is unacceptable for drinking water. Reverse Osmosis (R0) process has proven itself as the most practical and cost effective method of correcting problems caused by high TDS.
Nitrates are inorganic chemicals dissolved in some water supplies as a result of feedlot and agricultural activities. Nitrate levels over 45 mg/L as actual NO3 (or 10 mg/L as Nitrogen, N) can be a serious health risk to infants and children. Reverse Osmosis has proven itself as an effective method of reducing Nitrates to safe levels.
Heavy Metals-Lead (Pb);Cadmium (Cd);Mercury (Hg);Arsenic (As);Selenium (Se);Chromium (Cr)
The so-called heavy metals are toxic elemental metals such as Lead, Cadmium, Mercury, and Arsenic that find their way into water supplies from natural and industrial sources as well as home plumbing. These metals, especially Lead, can seriously affect the mental and neurological development of infants and children. Reverse Osmosis (R0) is recognized as the most practical method of reducing Lead to insignificant levels in drinking water. Carbon Block technology that incorporates ceramic ion exchange media is also an effective method of reducing lead.
Radium 226/228 (Ra)
Radium occurs in ground water due to the radioactive decay of Uranium in geologic formation. There is a health risk if the Radium level exceeds 20 pecocuries per liter (pCi/L). Cation exchange water softeners using proper regeneration procedures are effective in reducing Radium for POE applications. Reverse Osmosis systems are effective for reducing Radium for POU applications.
Our current testing procedure and sampling will test for the following:
- Coliform Bacteria