| Types of wells |
Drilled well
- 15 metres/50 feet to 60 metres/200 feet deep
- Small diameter
- Usually made of steel
Dug well
- 9 metres/30 feet or less deep
- Large diameter
- Usually made of concrete, rocks, bricks or wood
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| Well water contamination |
Contamination of your well water can be caused by bacteria and chemicals.
Bacteriological contaminants
What are total coliforms?
Total Coliforms are bacteria that are found everywhere in the environment including soil, plants, and in human and animal feces. Having total coliforms in your water may mean it is not safe to drink.
What is E. coli?
E.coli are bacteria that live in warm-blooded animals. Having E.coli in your water means it is not safe to drink.
Chemical contaminants
- Fuels
- Industrial solvents
- Pesticides and fertilizers
- Nitrates from animal and human waste
Facts About... Barium in well water
Facts About... Lead in drinking water
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| Well water sampling |
Taking a water sample
Test your drinking water for the presence of harmful bacteria at least three times a year.
View our nine step water sampling resource
Step 1
Use a water sample bottle with attached form. You can get these from the Health Department or Ontario Ministry of Health and Long-Term Care Public Health Laboratory.
Step 2
Remove all attachments from the faucet including the aerator, rubber washer and any hoses.
Step 3
Be sure to disinfect the tap with alcohol or plain bleach (5.25 per cent sodium hypochlorite).
Step 4
Run cold water tap for a minimum of five minutes.
Step 5
Unscrew cap from water sample bottle. Be sure not to contaminate the inside of the cap or the neck of the sample bottle with your fingers.
Step 6
Fill bottle to 200ml water line indicated on bottle.
Step 7
Screw cap on tightly.
Step 8
Fill out the form that is comes with the water sample bottle.
Remember to write the PIN on the form so you can get your results over the phone.
Step 9
Put bottle filled with water sample inside an insulated cooler with ice pack and take everything to the nearest drop-off location.
Note: All laboratories must receive water samples within 24 hours of the sampling date. Samples received after 24 hours will not be tested.
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| Drop-off locations and water sample bottles for bacteriological water testing |
Well water samples and COVID-19
Private well water samples continue to be accepted and submitted to the Public Health Laboratory for testing. Drop-off hours and locations currently are:
Monday to Friday from 8:30 a.m. to 4:30 p.m.
- 101 Consumers Drive, Whitby (east entrance)
- 181 Perry Street, Port Perry (east entrance)
Public health inspectors are available by phone should you have questions about water sampling, wells or water sample interpretation.
Please note that all residents dropping off water samples must be screened and pass in order to drop off a water sample. For questions please contact the Durham Health Connection line at 905-668-2020 (choose option “3”).
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| Bacteriological testing interpreting results |
Find more information on your water results.
What should I do if my well water is not safe?
- Stop using the well water and contact the Durham Health Connection Line.
- Do a visual check of your well (See the Homeowner well maintenance and inspection checklist).
- Disinfect your well.
- Call a licensed well technician.
- If you want to continue to use your water from your well, bring water to a rolling boil for at least one minute and let it cool before using it for drinking, making infant formula, juices, ice or recipes, brushing your teeth, rinsing contact lenses, and washing food or dishes. Refrigerate your boiled water until it is finished.
For more information read facts about boil water advisories.
Note: Your well water supply is only considered safe to drink after you have received three repeated water results of 0 total coliform per 100 mL and 0 E.coli per 100 mL. Each sample should be taken one to three weeks apart.
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| Disinfecting your well |
| Dug and bored well disinfection |
To disinfect your well you should shock chlorinate the system with a high concentration of bleach.
Protect your skin from splashes from the bleach by using gloves, goggles and clothing. Never mix bleach with other chemicals.
- Follow the chart below for correct measurements.
- Regular household bleach (Sodium Hypochlorite 5.25 per cent) should be used to chlorinate your well. Do not use "fresh scent" bleach or other products to disinfect wells.
Be sure you have another safe or potable source of water to use during this process.
Chlorine required for dug and bored wells casing diameter 0.9 metres or three feet
Water Depth
Meters | Water Depth
Feet | Household Bleach 5.25%
Litres | Household Bleach 5.25%
Quarts |
|---|
| 1.5 |
5 |
1.1 |
1 |
| 3.0 |
10 |
2.2 |
2 |
| 4.5 |
15 |
3.3 |
3 |
| 6.0 |
20 |
4.4 |
4 |
| 7.5 |
25 |
5.5 |
5 |
| 9.0 |
30 |
6.6 |
6 |
| 10.5 |
35 |
7.7 |
7 |
| 12 |
40
|
8.8 |
8 |
(Note: All Conversions Are Approximate)
Follow steps one through eight:
- Disconnect carbon or charcoal filters. Other treatment devices including water softeners, iron filters and sand filters should be chlorinated. Check first with the manufacturer's information to ensure that chlorine will not damage the treatment equipment.
- Turn off the heating element on your hot water heater to save energy during this process.
- Use the chart above to determine the amount of chlorine to disinfect the volume of water in your well.
- Mix the right amount of chlorine with water before applying it to the well using a ratio of one unit volume of bleach to 10 units of water (e.g. one litre of bleach for every 10 litres of water).
- Turn on all taps/faucets to send chlorinated water throughout the plumbing system until you can smell chlorine.
- Let the water stay in the system for 12 to 24 hours.
- Flush the system of remaining chlorine.
- Do not drain chlorinated water into your septic system.
- Do not drain the water to a stream or pond.
- Connect a hose to an outside tap and drain the water onto a remote location on the property away from the septic system and well.
- Once the smell of chlorine lessens, you can turn on the indoor faucets until the smell of chlorine is completely gone.
- Wait one week before collecting a water sample for bacteriological testing so that all remaining of chlorine has been flushed from the system.
If shock chlorination treatment does not get rid of the bacteriological problem or you have ongoing contamination in your well, the Health Department suggests you consider a water treatment device and contact a licensed well water technician.
For more information please see the Homeowner well maintenance and inspection checklist.
|
| Drilled well disinfection |
To disinfect your well you should shock chlorinate the system with a high concentration of bleach.
Protect your skin from splashes from the bleach by using gloves, goggles and clothing. Never mix bleach with other chemicals
- Follow the chart below for correct measurements.
- Regular household bleach (Sodium Hypochlorite 5.25 per cent) should be used to chlorinate your well. Do not use "fresh scent" bleach or other products to disinfect wells.
Be sure you have another safe or potable source of water to use during this process.
Chlorine required for drilled wells casing diameter up to 15 centimetres or six inches
Water Depth
Meters | Water Depth
Feet | Household Bleach 5.25%
Millilitres | Household Bleach 5.25%
Ounces |
|---|
| 7.6 |
25 |
140 |
5 |
| 15.0 |
50 |
280 |
10 |
| 22.8 |
75 |
420 |
15 |
| 30.0 |
100 |
560 |
20 |
| 38.0 |
125 |
700 |
25 |
| 45.0 |
150 |
840 |
30 |
| 53.0 |
175 |
980 |
35 |
| 61.0 |
200 |
1,120 |
40 |
(Note: All conversions are approximate.)
Follow steps one through eight:
- Disconnect carbon or charcoal filters. Other treatment devices including water softeners, iron filters and sand filters should be chlorinated. Check first with the manufacturer's information to ensure that chlorine will not damage the treatment equipment.
- Turn off the heating element on your hot water heater to save energy during this process.
- Using the chart above, determine the amount of chlorine to disinfect the volume of water in your well.
- Mix the right amount of chlorine with water before applying it to the well using a ratio of one unit volume of bleach to 10 units of water (e.g. one litre of bleach for every 10 litres of water).
- This procedure can be performed using a large, clean container.
- Add the chlorine through the top of the dug or bored well by removing the lid and splashing the chlorine mixture around the wall or lining of the well to make sure that the solution touches all parts of the well casing.
- Turn on all taps/faucets to send chlorinated water throughout the plumbing system until you can smell chlorine.
- Let the water stay in the system for 12 to 24 hours.
- Flush the system of remaining chlorine.
- Do not drain chlorinated water into your septic system.
- Do not drain the water to a stream or pond.
- Connect a hose to an outside tap and drain the water onto a remote location on the property away from the septic system and well.
- Once the smell of chlorine lessens, you can turn on the indoor faucets until the smell of chlorine is completely gone.
- Wait one week before collecting a water sample for bacteriological testing so that all remaining of chlorine has been flushed from the system.
If shock chlorination treatment does not get rid of the bacteriological problem or you have ongoing contamination in your well, the Health Department suggests you consider a water treatment device.
For more information please see the Homeowner well maintenance and inspection checklist.
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|
| Water treatment devices |
|
Water treatment devices may include ultra-violet irradiation, chlorination, ozonation, distillation, activated carbon devices and reverse osmosis devices.
Treatment device methods and uses
| Method | Uses |
|---|
| Chlorination |
- Kills bacteria and viruses
- Can be used to remove some forms of iron, as long as water is filtered after chlorination
|
| Ultra-Violet |
Kills bacteria and viruses |
| Filters |
- Use ceramic candle filters to remove bacteria and parasites, but not viruses
- Use other filter types to remove sand, sediment, rust and particles
- Use specially rated filters to remove very small particles
|
| Reverse Osmosis |
Removes nitrates, sulphates, hardness, most microbes, dirt particles and small amounts of some pesticides |
| Ozonation |
- Kills most microbes, but not cryptosporidium
- Removes organic compounds, including pesticides
- Can be used in combination with activated carbon filters
|
| Activated Carbon Contactors |
- Remove small amounts of some chemicals
- Used for removing tastes and odours, and reducing trace levels of organic chemicals (e.g., pesticides)
|
| Distillation |
- Kills all microbes by heat
- Removes heavy metals and nitrates
- Often used in combination with activated carbon filters
|
| Softeners |
- Kills all microbes by heat
- Removes heavy metals and nitrates
- Often used in combination with activated carbon filters
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|
| Well maintenance and inspection |
|
Wells require maintenance as they age. Use the Homeowner well maintenance and inspection checklist to inspect your well regularly.
Warning: Do not enter the well or well pit at anytime during and inspection.
When a well is no longer in use contact the Ministry of Environment and Climate Change. |
| Well records |
| Your well contractor must give you a copy of your water well record. Visit the Ontario Ministry of the Environment and Climate Change (MOECC) for information about your well record. |
| Well abandonment |
You should think about properly abandoning or plugging your well if:
- A new well is drilled and you are no longer using the old well.
- The water quality is bad and you need another water supply.
An Ontario Ministry of the Environment and Climate Change (MOECC) licensed well contractor must be hired to abandon the well.
*Source: Best Management Practices: Water Wells (Ontario Ministry of Agriculture, Food and Rural Affairs/Agriculture and Agri-Food Canada)
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