The pH of water is the "negative log of the Hydrogen ion concentration (activity). The technical definition of pH is that it is a measure of the activity of the hydrogen ion (H+) and is reported as the reciprocal of the logarithm of the hydrogen ion activity. This means - A water with a pH of 7 has 10-7 moles per liter of hydrogen ions; whereas, a pH of 6 is 10-6 moles per liter."
Put another way, if the water has a pH of 7, it means that the concentration of hydrogen ions equals the concentration of hydroxide ions (OH–), both having a concentration of 10–7 moles per liter of water. Hydrogen ions make the water acidic; hydroxide ions make the water basic. Since the concentrations are equal at a pH of 7, the water is neutral; it is neither acidic nor basic. However, since pH is a logarithmic scale, if the pH is 6, it means that the concentration of hydrogen ions becomes 10–6 and the concentration of the hydroxide ions is 10–8; the concentration of the hydrogen ions in water with a pH of 6 is ten times the amount of hydrogen ions in water with a pH of 7. Each time you change the pH by 1, you change the hydrogen ion concentration by a factor of ten so water with a pH of 5 would have 100 times the hydrogen ion concentration of water with a pH of 7 and so on. It works the same way with a pH greater than 7. At a pH of 8, the concentration of hydrogen ions would be 1/10th that of water with a pH of 7 (but the concentration of the hydroxide ion would be ten times more). Once the hydroxide ion concentration becomes more than the hydrogen ion concentration, the water becomes basic. The point is that a small change in pH can mean a big difference in how acidic or basic the water is.
The pH scale ranges from 0 to 14. In general, water with a pH < 7 is considered acidic and with a pH > 7 is considered basic. The normal range for pH in surface water systems is 6.5 to 8.5 and for groundwater systems 6 to 8.5. For perspective, milk has a pH of about 6.6 and vinegar (acetic acid) and stomach acid (hydrochloric acid) a pH of around 2.5. Human blood is usually around 7.4 compared to sea water at 8.1 and household bleach and ammonia between 11 and 12. Incidentally, it can be a bad idea to mix two solutions of very different pHs. Mixing bleach with vinegar will release chlorine gas.
Alkalinity is a measure of the capacity of the water to resist a change in pH that would tend to make the water more acidic. A common example of this would be water with some calcium carbonate (CaCO3) dissolved in it. Acid could be added to such a solution (up to a point) without changing the pH. The more acid that can be added without changing the pH, the greater the alkalinity of the water. The measurement of alkalinity and pH is needed to determine the Corrosivity of the water; generally, the higher the alkalinity, the lower the corrosivity. Note that alkalinity and pH are not the same nor is the pH of the water a measure of the strength of the acidic or basic solution; pHalone does not provide a full picture of the characteristics of the water.
The pH of pure water (H20) not exposed to our atmosphere is 7 at 25℃, but when exposed to the carbon dioxide in the atmosphere, this equilibrium quickly changes to a pH of approximately 5.2; CO2 in the air dissolves in the water and becomes carbonic acid (H2CO3). Fortunately, most water is not ‘pure’ and contains dissolved ions, some of which may help keep the water near neutral and non-corrosive; note that ‘pure’ water would have an alkalinity of zero. Because of the association of pH with atmospheric gasses, temperature, and dissolved ions, it is strongly recommended that the pH of the water be determined as soon as possible.
The pH of the water is not truly a measure of the acidity (low pH) or basicity (high pH) of the water, but it can be used as a guide to help understand how likely there may be a problem. In general, a water with a low pH (< 6.5) could be acidic, soft, and corrosive. Therefore, the water could leach metal ions such as Iron, Manganese, Copper, Lead, nickel, chrome, and Zinc from the aquifer, plumbing fixtures, and piping. A water with a low pH could contain elevated levels of toxic metals, cause premature damage to metal piping, and have associated aesthetic problems such as a metallic or sour taste, staining of laundry, and the characteristic "blue-green" staining of sinks and drains. The low pH could suggest a high concentration of carbon dioxide gas and the presence of bacteria.
A water with a pH> 8.5 could indicate that the water is hard and aggressive. Hard water does not normally pose a health risk, but can cause aesthetic problems. The problems associated with hard and aggressive water can include: formation of a"scale" or precipitate on piping and fixtures causing water pressures and interior diameter of piping to decrease; causing the water to have an alkali taste and making coffee taste bitter; forming a scale or deposit on dishes, utensils, and laundry basins; making it more difficult to get soaps and detergents to foam and facilitating the formation of insoluble precipitates on clothing, etc.; and decreasing the efficiency of and possibly violating the warranty of boilers, on-demand water heaters, heat-exchange units, and other appliances and mechanical systems associated with using or heating/cooling the water.
The health risks are not directly linked to the actual pH but drinking water with a very low or high pH can damage tissues in the body. The normal pH of the skin ranges from 4.5 to 6.5. "Arterial blood has a pH of 7.4, intracellular fluid a pH of 7.0 and venous blood and interstitial fluid, i.e., fluid around the cells, has a pH of 7.35.
Examples of pH of common consumer products and human biological fluids
DO NOT PANIC!
A pH of 1 is 10 times more acidic than a pH of 2 and 100 times more acidic than a pH of 3. Therefore, soda at a pH of 2 would be 10,000 times more acidic than well water with a pH of 6.
The EPA has a recommended secondary drinking water standard that ranges from 6.5 to 8.5 and some states have established this as a formal standard. This standard is set as a guide and the general understanding is that a potable water within this range is less likely to have a significant problem. In general, this may be true, but it does not mean there are no problems or concerns. If the pH is low, the water could be corrosive to piping and other infrastructure, could have a higher concentration of metals, and could damage skin and tissue. If the pH is high, the water may be aggressive and create coatings, films, and precipitates that clog or damage systems or "burn" tissue, i.e., the water can become caustic.
pH is not a typically classical contaminant in drinking water; it is more like a condition. In extreme cases, the pH of the water can cause acute and chronic problems, but in most cases the pH of the water is used to measure the condition of the water and determine how likely the water may corrode piping or plumbing fixtures, influence the metal content of the water, or clog the system with a chemical scale. If possible we recommend measuring the pH of the water in the field at the point-of-use and also collecting a water sample for laboratory analysis (be aware that the pH of the sample can change in transit which is why it is important to try to test the pH in the field). Your best course of action is to get a comprehensive water quality test. If the field-measured pH is less than 6.5, we would recommend testing the sample for trace metals and the potential for corrosion. If the pH is over 8.5 or chemical scales are present, we would recommend testing for aggressive water and additional trace metals like Aluminum (some things are much more soluble at low pH, others at high pH).
Level 1 Testing is done with simple observations that an individual can make with their own senses such as sight, smell, and taste. These observations can be readily apparent or can be observed as they change over time. In addition, accessible related information about the home can also be used to narrow down the cause of your water issues.
There are a number of ways to evaluate the pH of the water. If the water has a bitter metallic taste or humic color like tea, the pH of the water is likely low. If the pH of the water is high, you may experiencing problems with chemical scale and coatings. The water may have an alkali or soapy taste and you may think you have Hard Water.
Our primary recommendation is to attempt to identify the problems you are experiencing with the water; see if you are experiencing chemical scale formation or coating or if you are experiencing corrosion issues. Also, it would help if you can determine whether the water has an off-taste.
Level 2 Testing is Do-It-Yourself testing that can be done in your own home using a Testing Kit. After you’ve done Level 1 Testing, Level 2 Testing can confirm if your observations are correct. If your test results reveal the presence of a contaminant that is cause for concern, you can either proceed to determine the best treatment (see below) or continue to Level 3 Testing.
There are a number of low-cost, in-home, and field-screening kits and meters for measuring the pH of your water. We have found the Hanna Meter both easy to use and affordable, if you are going to conduct multiple pH tests on a regular basis.
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Level 3 Testing is done through an accredited Water Testing Laboratory. With Level 3 Testing, you can order a testing kit that is used to prepare your sample and submit it to the lab. By utilizing a lab, you have the assurance that a certified water expert had analyzed your water sample. If your test results reveal the presence of a contaminant that is cause for concern, you can either proceed to determine the best treatment options (see below) or continue to Level 4 Testing - Certified Testing.
It is best to measure the pH at the time of sampling. We recommend ordering the pH meter mentioned in Level 2. If you suspect the water has a corrosion problem, we suggest the National Testing Labs Corrosion Check. If you are just checking your city or well water, we recommend the National Testing Labs Basic kits.
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<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L</div>
<div class="product-note in-L4-methyl-tertiary">Note: Concentrations < 40 ppb</div>
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L</div>
<div class="product-note in-L6-uranium">Note: Uranium less than < 0.030 mg/L</div>
<div class="product-note in-L6-alkalinity">Note: For Low Hardness / Alkalinity/ Low pH</div>
A Level 4 Certified Test Test uses chain-of-custody with a water professional coming to your home to prepare the water sample and then works with an accredited laboratory in order to certify your test results. This type of testing not only gives you the highest level of assurance in the accuracy of your test results, but can also be used as a document in legal cases. For Baseline Testing, we recommend that you use Certified Testing.
A water treatment system is not normally designed or selected simply based on the pH of the water. It is necessary to understand the underlying problem or condition. Therefore, it is necessary to get a detailed water quality analysis which would include a comprehensive evaluation of the general water and Bacterial quality of your drinking water in order to understand the systems within the home or building that may be vulnerable to corrosive or scale-forming water.
In the short term, there are a number of options if you believe the pH of the water is low. You can flush the water line prior to use and then collect the water and allow the water to stand, allowing any carbon dioxide to come out of the water. This may cause the pH of the water to rise if dissolved carbon dioxide is a significant contributor to the low pH. You can consider the use of a point-of-use filter that contains media that adjust the pH and removes trace metals or you can use an alternative water source. If the pH of the water is elevated, it may be best to use an alternative drinking and bathing water source.
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<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L</div>
<div class="product-note in-L4-methyl-tertiary">Note: Concentrations < 40 ppb</div>
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L</div>
<div class="product-note in-L6-uranium">Note: Uranium less than < 0.030 mg/L</div>
<div class="product-note in-L6-alkalinity">Note: For Low Hardness / Alkalinity/ Low pH</div>
Recommendation: Seek Advice from a Local Professional (Customized Solution). Contact Us
In many cases, the long-term treatment will include a whole-house treatment system with either a neutralization system to increase the pH of the water or a chemical feed system to lower the pH of the water. At the same time, it is highly likely that other water quality issues will need to be addressed. Before installing a long-term treatment system it will be necessary to get your water tested and your existing plumbing/piping system inspected by a professional. Like any whole-house water treatment system, the system will require annual maintenance and performance monitoring. We strongly recommend hiring a certified installer and using certified treatment equipment and chemicals.
<div class="product-note in-L4-carbon-filtration">Note: For rural Areas with <a href="/indoor-6/herbicides-pesticides">Herbicides and Pesticides</a> Usage</div>
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L</div>
<div class="product-note in-L4-methyl-tertiary">Note: Concentrations < 40 ppb</div>
<div class="product-note in-L6-bromate">Note: If the concentration is < 0.01 mg/L</div>
<div class="product-note in-L6-uranium">Note: Uranium less than < 0.030 mg/L</div>
<div class="product-note in-L6-alkalinity">Note: For Low Hardness / Alkalinity/ Low pH</div>
Recommendation: Seek Advice from a Local Professional (Customized Solution). Contact Us
