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Frequently Asked Questions (FAQ) - Water


Why is chlorine used in drinking water?
It is required by law to add a disinfectant to public drinking water. Chlorine is an effective disinfectant that kills harmful bacteria and viruses found in natural fresh water. Peterborough Utilities Commission has been using chlorine to disinfect our drinking water since 1916.
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Is fluoride in drinking water safe?
While provincial drinking water standards do not include mandatory fluoridation, many municipalities have chosen to fluoridate their water for the benefit of their customers. The City of Peterborough Bylaw 1973-1 requires us to fluoridate the City’s drinking water to levels of 0.50 and 0.80 mg/L leaving the Peterborough Water Treatment Plant. At these concentrations, no ill health effects have been linked to the fluoridation of drinking water and it has noticeably improved the dental health of Peterborough residents. Peterborough's Medical Officer of Health and the Canadian Dental Association endorse the fluoridation of municipal drinking water.
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What causes my tap water to appear cloudy white?
When water flows from your tap, tiny bubbles from dissolved air can be released and make your tap water appear cloudy. This problem is more frequent in winter, as cold water holds air longer than warm water. Cloudiness caused by air bubbles does not pose a health concern, but for some people it is unappealing. After a few minutes, these air bubbles disappear from a standing glass, so a good solution to this problem is to keep a jug of tap water in the fridge for drinking.
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Are all chemicals in my drinking water bad for me?
Many people assume that all chemicals are health hazards, but this is an unfair assumption. While some chemicals in drinking water can be unhealthy, other chemicals, such as fluoride and chlorine, are quite beneficial in correct amounts. The Provincial government has established safe concentrations in drinking water and frequent testing ensures that safe concentrations of all chemicals exist in your drinking water.
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What could cause my tap water to have a rusty colour?
Routine repairs or flushing of fire hydrants and watermains can stir up sediment and cause red or brown coloured tap water. This colouring is not a health concern, but can stain laundry and fixtures. Running your cold water taps for a few minutes will usually flush out any sediment in your system.

If your hot water alone appears coloured, sediment in your water heater is likely to blame. Try draining the water from the bottom of your water heater to flush out these unwanted minerals. Repeat this procedure annually to prevent further build-up of sediment.
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Where does our drinking water come from?
The source of raw, untreated water for Peterborough’s drinking water is the Otonabee River. The Otonabee River water is of good quality and can be described as a moderately coloured water of low turbidity. The river water temperature ranges from 0°C in winter to approximately 26°C in summer. Water is continuously being treated and tested to ensure that customers always have access to drinking water that meets or exceeds all drinking-water standards set by the Ministry of Environment.
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What is the major cause of pollution in our drinking water source?
Rainwater flows over lawns and roads, into storm sewers, and then directly into local waterways, carrying with it dissolved pesticides, salts, oil, and other untreated waste products. Faulty septic systems adjacent the water course and waterfowl living in the Otonabee River also contribute pollution. Fortunately, the treatment process at the Peterborough Water Treatment Plant is very effective in treating this pollution to produce safe clean drinking water.
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What could cause my tap water to have a taste or odour?
Our drinking water meets or exceeds all provincial standards for water quality, but sometimes customers notice either chlorine or earthy tastes in our water.

The Peterborough Utilities Commission has been using chlorine since 1916 to maintain high standards of water quality. Sensitive customers may notice a chlorine taste in Peterborough’s tap water. Leaving a jug of tap water in the fridge for drinking will often solve this problem. Just leave a small space of air at the top, and the chlorine taste will evaporate from the water.

Some types of river algae living in the Otonabee River produce a nontoxic compound that can cause an earthy taste. Even in extremely small concentrations, this taste can be noticeable for sensitive customers, especially during summer months when water temperatures are warmer. Some customers may choose to purchase an activated carbon filter to remove such tastes from their tap water. These filters are effective at removing many tastes and odours, but it’s important that they are properly maintained according to the manufacturer’s instructions.

For more information on the advantages and disadvantages of home treatment products, see Health Canada’s web page.
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How can I minimize my exposure to lead in my older home?
Lead from piping in older homes can dissolve into the house’s water supply if left standing for long periods of time. To minimize exposure to lead, never drink or cook with water that has been standing in your pipes for longer than six hours. Run the taps until the water feels colder to the touch, and use the flushed water for household cleaning or watering plants instead.  Of course removal of sources of lead, such as lead pipes or lead solder is the best way to minimize your exposure to lead in the long-term.
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Is it okay to use hot water from the tap for cooking?
Metals from household piping and water heaters dissolve into warm water more readily than cold water. This makes water from your hot water heater more likely to contain potentially harmful contaminants. Cold water should be used for household cooking as much as possible.
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Why do some people buy bottled water or use in-home water treatment devices?
The water supplied by the Peterborough Utilities meets or exceeds all provincial water quality standards, and is perfectly safe for everyday drinking and cooking. Some people who are sensitive to tastes or odours may use bottled water or in-home filters for drinking. This is a personal choice.
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Is it safe to drink water from a garden hose?
While the water in the hose has gone through the same treatment processes as the water coming from a tap inside your house, the hose itself is treated with harmful chemicals that keep it flexible. These chemicals, along with bacteria and other things that might be growing inside your hose are not good for you to drink.
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How "hard" is Peterborough tap water?
Peterborough tap water, with calcium and magnesium concentrations of approximately 6 grains/gallon (95 mg/L), is considered to be moderate in terms of hardness. Water is considered hard when the concentration of calcium and magnesium exceeds 7 grains/gallon (120 mg/L). These minerals do not pose a health risk, but can make it difficult to work up a lather, and can leave deposits in showers or on dishes.
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Is it true that tap water quality is getting worse?
Advances in technology have given chemists and microbiologists the ability to detect more contaminants than ever before. This, plus the general public being more concerned about water quality issues creates the illusion that water quality is getting worse, but actually the opposite is true. Drinking water quality regulations are far stricter than they have been in the past, allowing for far lower levels of regulated chemicals and microbes. Better testing and monitoring equipment ensure the consistent quality of your drinking water.
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How does the Peterborough Utilities Commission monitor water quality?
Over 20,000 water quality tests are performed on Peterborough’s water annually. Bacteriological tests are performed five times a week, testing for the presence of E. coli and coliforms, while levels of iron, aluminium, silica, alkalinity and hardness are checked monthly. Advances in technology allow for chlorine residual, turbidity, and fluoride levels to be continuously monitored. Additional tests are performed as needed to ensure that the quality of Peterborough’s water remains high.

In addition to regular testing at the Water Treatment Plant, several thousand samples are sent out annually to a certified laboratory for further tests, and samples are sent out quarterly to the Ministry of the Environment’s Drinking Water Inspection Survey Program (DWISP). The Ministry of the Environment also inspects the Water Treatment Plant regularly, and performs their own sampling and testing of the water.
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What are THMs? Should I be worried about them in our water?
Chlorine is a very effective disinfectant that has been used successfully to treat Peterborough’s drinking water for many years. Chlorine purifies water by killing harmful bacteria and other germs that pose health threats, but sometimes it can react with non-toxic, organic substances in the water to produce disinfection by-products (DBPs). Trihalomethanes (THMs) are regulated DBPs that can be formed during the disinfection process. As a result, THM’s are tested quarterly both at the treatment plant and out in the distribution system, to ensure that concentrations are at acceptable levels as established by the Ministry of the Environment.
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Where do the white or tan particles in my water come from?
White or tan particles in tap water usually come from the inside of your pipes, water heater, or water softener. These particles can be a combination of calcium carbonate and magnesium carbonate, and are often referred to as pipe scale. Calcium and magnesium carbonates are naturally occurring minerals and are found in varying concentrations in most waters around the world. These minerals are not a health threat; in fact, they are beneficial to human health. The amount of these minerals in the water determine the hardness of the water; higher mineral concentrations make the water harder. Over time, these minerals can deposit on the inside of your pipes and then begin to flake off. If you add a water softener to your plumbing system, the softer water can begin to re-dissolve the minerals from the pipes and pieces may begin to break loose. These are all common causes of pipe scale in the water and account for most customer complaints about white or tan particles in the water. Although pipe scale is not a health hazard, it can be a nuisance by clogging inlet screens to washing machines, showerheads, and faucet aerators (the screen that screws on to the end of the water faucet).
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