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CAUTION: Confined Spaces

Small, enclosed spaces such as a cistern, septic tank, some farming and industrial equipment, well (dug / bored wells) or a well pit, may be considered Hazardous Confined Spaces and should never be entered by anyone other than a trained professional.


For more information on Hazardous Confined Spaces please visit:


Some rural residents obtain their drinking water from a reservoir or cistern, typically made of concrete or a food grade certified material. A cistern is used in areas where wells do not provide sufficient water yield or do not provide safe water for drinking. A properly maintained cistern, filled with municipally treated water that is delivered by an approved water hauler, should provide water that is safe to drink. However, cisterns still require regular inspection to make sure the cistern is clean, and water sampling to ensure the water is safe to drink. Poorly maintained cisterns are easily contaminated.

Maintaining your cistern

  • Make sure there are no cracks or holes in your cistern and that the lid is properly sealed. Check that vent screens are intact. This will keep any wildlife (e.g. frogs) from entering your cistern and will also keep out any contaminated surface water.
  • Inspect your cistern regularly. Look inside for any sediment, debris, or wildlife.
  • Do not direct rainwater from eaves troughs into your cistern. Bacteria from bird and animal droppings, dust, leaves, and chemical residues from roofing material will contaminate your cistern and drinking water.
  • Fill your cistern with potable drinking water only. Do not use water from an untreated water supply, lake, or river. You can check HNHU’s Disclosure Website for a list of drinking water haulage vehicles that have been inspected by the Health Unit.

Cleaning your cistern

  • Slime and sludge may accumulate on the bottom of your cistern. This will significantly affect the water quality and needs to be cleaned.
  • To clean your cistern, empty the cistern and remove all sediment and debris. Any cistern that requires entry into it for maintenance and cleaning should be considered a confined space. Hazardous gases or low oxygen levels may be present. Only individuals trained in confined space entry should enter a cistern.

Disinfecting your cistern

Your cistern needs to be disinfected after it has been cleaned, if you get an adverse water test result, or if you know your water has been contaminated (e.g. see dead wildlife inside). Before starting this process, it is recommended that you have a supply of bottled water to last for at least 2-3 days.

  1. Before disinfecting, make sure that your cistern is clean (remove all dirt and sediment), and is in good condition (holes or cracks fixed).
  2. Add 1 litre of household (5.25%) unscented bleach for every 1000 litres of water that your cistern holds. Add the bleach as you are filling up your cistern so that it mixes with the water. Fill your cistern to the top.
  3. Run each faucet (one at a time) in your house until a chlorine odour is noticed. If no odour is noticed, add a little more bleach to the cistern.
  4. Let the water stand overnight (minimum 12 hour contact time is required).
  5. After 12 hours, drain all of the water from your cistern through an outside hose, away from your septic system.
  6. Refill your cistern with hauled municipal water.
  7. Submit a water sample to the HNHU. Follow the instructions provided with the water bottle sample kit.
  8. Do not drink the water (or use it for brushing teeth, or washing fruit and vegetables) until you have received your water test results. The water should be safe for laundry and flushing the toilet, as well as bathing and showering as long as the water is not ingested.

Testing your cistern water

  • Test your water for bacteria regularly, and test if there is a change in how the water tastes, smells, or looks. Be sure to test your water after any repairs, after a flooding event, or if your cistern has not been used for long periods of time (weeks).
  • Free sample kits for bacteria testing are available from the Haldimand-Norfolk health Unit office locations listed below.
  • The freshness and temperature of your sample is essential for accurate testing. Drop off your sample as soon as possible or within 24 hours of collection, and keep it cool in transit.
  • If your test results show your drinking water is unsafe, stop drinking it. Call the Haldimand-Norfolk Health Unit to speak with a Public Health Inspector for advice on what to do next.


Drinking Water Sample Pick-up and Drop-off locations

12 Gilbertson Dr.
Simcoe, ON
519-426-6170 or
100 Haddington St.
Caledonia, ON
117 Forest St. E
Dunnville, ON








  • Sample bottles may be picked up any day, Monday to Friday between 8:30 am to 4:30 pm.
  • Follow the instructions included with the water bottle sample kit to sample your water.
  • Once you have filled the bottle with a water sample, drop of the sample and completed form to any Health Unit location listed above. Drop off samples Monday to Thursday between 8:30 am to 4:30 pm.
  • Samples ARE NOT ACCEPTED ON FRIDAY. Lab analysis must occur within two days of receiving the sample and cannot be sent on a Friday or over the weekend.

Drinking Water Haulers 

  • Drinking water haulage vehicles transport and deliver potable water.
  • The Health Unit inspects local water hauler vehicles annually or biannually, based on a risk assessment, to ensure operators are in compliance with guidelines and standards.
  • Check for the HNHU inspection sticker on any Water Hauler that is filling your cistern.

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