E. Coli in Cisterns: Risks, Testing, and Prevention

E. Coli and bacteria in cisterns

E. Coli in Cisterns: Risks, Testing, and Prevention

Cisterns are a reliable source of water for many households, cottages, farms, and off-grid properties. They provide essential storage, especially in areas without municipal water connections. But with any private water supply comes responsibility. One of the biggest risks cistern owners face is contamination, especially from E. coli.

E. coli in cisterns is more common than many people realize, and it can pose serious health risks if not addressed. This article explores how ecoli gets into cisterns, what it means for your health, how to test for it, and the best ways to prevent and manage contamination.

What is E. Coli?

E. coli, short for Escherichia coli, is a type of bacteria commonly found in the intestines of humans and animals. While many strains are harmless, some can cause illness when consumed in drinking water.

The presence of E. coli in a cistern is a red flag. It signals that the water has been contaminated with fecal matter, which may also contain other dangerous pathogens, viruses, or parasites. In other words, if your cistern tests positive for E. coli, it’s not just bacteria you need to worry about; it’s a broad indicator of unsafe water.

How Does E. Coli Get Into a Cistern?

Cistern contamination can happen in several ways:

1. Surface Runoff and Rainwater

If your cistern collects rainwater, contamination can occur when bird droppings or animal waste wash off the roof and into the tank. Even a small amount of droppings can introduce harmful bacteria.

2. Unsealed or Damaged Lids

A cracked or poorly sealed cistern lid invites trouble. Animals, insects, or debris can enter and introduce bacteria.

3. Water Delivery Trucks

If you rely on water deliveries, the truck hoses, tanks, or handling methods may not always be sanitary. One contaminated delivery is enough to seed your cistern with E. coli.

4. Nearby Septic Systems

Leaking or improperly maintained septic tanks can leach bacteria into the ground, eventually making their way into underground cisterns or water storage areas.

5. Poor Maintenance

Over time, sludge and biofilm can build up inside a cistern. This creates a perfect environment for bacteria to grow, especially if the tank is never cleaned or disinfected.

Health Risks of E. Coli in Cisterns

The health risks depend on the strain and the amount of exposure, but drinking or cooking with water contaminated by E. coli can lead to:

Mild to severe diarrhea

Stomach cramps

Nausea and vomiting

Fever

In severe cases, particularly with the strain E. coli O157:H7, infection can cause kidney damage and even be life-threatening—especially for young children, the elderly, or people with weakened immune systems.

Even if you don’t drink directly from your cistern, contaminated water can still be dangerous if used for brushing teeth, washing food, or accidentally swallowed during bathing.

How to Test for E. Coli in Your Cistern

The only reliable way to know if your cistern contains E. coli is to test it. Here’s how:

1. Collect a Water Sample
Use a sterilized bottle from a local health unit or certified lab. Take the sample from a tap that’s fed directly from the cistern, not from a filtered or treated line.

2. Submit to a Lab
Most health departments or private labs can test water samples for E. coli and total coliform bacteria. Results usually take 24–48 hours.

3. Interpret the Results

    – No E. coli detected: Your water is currently safe from fecal contamination.

    – E. coli detected: Immediate action is required. Do not drink the water until it is disinfected and retested.

    – Total coliforms detected: While not as dangerous as E. coli, this indicates possible contamination pathways.

    Routine testing is key. Many experts recommend testing cistern water at least 3–4 times per year, especially after maintenance, refilling, or heavy rains.

    Free E. coli testing is available for all private wells in Ontario. Ontario.ca

    How to Remove E. Coli from a Cistern

    If a test comes back positive for E. coli, don’t panic; it can be dealt with. Here are the common steps:

    1. Disinfection with Chlorine

    The most common solution is to shock-chlorinate the cistern:

    – Drain the tank if possible.

    – Scrub and rinse the interior to remove sludge and debris.

    – Refill with clean water.

    – Add a chlorine solution (household bleach without additives works in emergencies) and circulate through the system.

    – Allow the water to sit for several hours before flushing.

    2. UV Filtration Systems

    Installing a UV (ultraviolet) water purifier at the point of entry is a great long-term defense. UV systems kill bacteria like E. coli instantly without altering the taste of the water.

    3. Ongoing Chlorination or Ozone

    For households at high risk, a continuous disinfection system using chlorine or ozone can keep water safe.

    4. Professional Cleaning

    If your cistern has years of buildup, hiring a professional cleaning service ensures a thorough job. Or DIY cistern clean!

    Preventing E. Coli in Cisterns

    Prevention is always better than dealing with contamination after the fact. Here are best practices:

    – Keep lids tightly sealed to prevent animal entry.

    – Clean and disinfect your cistern annually.

    – Inspect delivery hoses and request clean handling from water delivery companies.

    – Install a first-flush diverter if using rainwater collection to redirect the initial dirty water off the roof.

    – Test your water regularly to catch problems early.

    – Add a point-of-use filter (such as reverse osmosis) for drinking water taps.

    Common Questions About E. Coli in Cisterns

    Can boiling water kill E. coli?
    Yes. Boiling water for at least one minute kills E. coli and most other pathogens. This is a safe short-term solution until the cistern is disinfected.

    Can I use bleach in my cistern all the time?
    Small amounts of chlorine can help keep water safe, but too much can affect taste and smell. Regular testing is needed to keep levels balanced.

    If my cistern tests positive once, will it always be contaminated?
    Not necessarily. A one-time incident may be solved with cleaning and disinfection, but ongoing contamination suggests a larger problem with your system or environment.

    Final Thoughts

    E. coli in cisterns is not something to ignore. It signals a serious breach in water safety that can affect your health and the health of your family. The good news is that with regular testing, good maintenance practices, and effective disinfection strategies, you can keep your cistern water safe and reliable.

    A cistern should be a dependable water source, not a hidden health hazard. By staying proactive, you can enjoy clean, safe water all year round.

    And if you want to learn how to monitor the liquid level in your cistern, please check out our Canadian-made PTLevels!

    Comparing Pressure Sensors and Ultrasonic Sensors for Liquid Level Management

    PTLevel Pressure Chamber

    A Comparative Analysis of Pressure and Ultrasonic Sensors for Liquid Measurement

    In the realm of liquid measurement, selecting the appropriate sensor is crucial for accurate and reliable results. We’ve put together a comparative analysis of pressure sensors and ultrasonic sensors used for liquid level monitoring and measurement. We hope the details on advantages and considerations are helpful as you plan your liquid level management. Among the myriad options available for liquid level measurement, pressure sensors and ultrasonic sensors stand out as two prominent contenders. This article aims to provide a comprehensive comparative analysis of these sensors, aiding readers in making an informed decision based on their specific application requirements. (Spoiler alert – we think pressure sensors, especially the PTlevel, win!)

    sample pressure sensor for liquids

    Pressure Sensors

    Benefits: Provides greater accuracy, cost-effective, can handle environmental extremes, low maintenance

    sample ultrasonic sensor for liquids

    Ultrasonic Sensors

    Benefits: Non-contact with liquid, easy installation

    Pressure Sensors (like the PTLevel):

    Pressure sensors operate on the principle of detecting the force exerted by a liquid on the sensor element. These sensors excel at measuring liquid depth, finding widespread application in tasks such as monitoring tank levels, overseeing industrial processes, tracking cistern levels, monitoring septic and holding tanks, and managing rainwater harvesting systems. Here are some key advantages and considerations when opting for pressure sensors:

    Advantages of Pressure Sensors:

    Accuracy and Precision: Pressure sensors exhibit remarkable accuracy and precision, particularly in applications where precise pressure measurements are essential. The PTLevel uses a 0kpa-100kpa sensor with an accuracy of 0.096kpa per bit, which is about 9.78mm of resolution.

    Cost-Effectiveness: In many cases, pressure sensors are more cost-effective than their ultrasonic counterparts, making them a preferred choice for budget-conscious projects. And in every case we can find, the PTLevel beats the price of comparative systems with ultrasonic sensors!

    Reliability in Specific Environments: Pressure sensors perform well in environments with challenging environmental conditions, such as high temperatures, freezing temperatures, or corrosive substances. Condensation, frost, and high humidity are not a concern for pressure sensors. (Yes, the PTLevel is also chemical resistant, weather resistant -40°C to 100°C temperature range, and built by Canadians for tough North American winters, making it ready to handle your most challenging environment!)

    Low Maintenance: Pressure sensors require very little, or easy maintenance to operate accurately. For instance, pressure sensors sometimes have to have their “pressure” calibrated or reset. In the case of the PTLevel, we recommend seasonal maintenance to reset the air-pocket.

    PTLevel Pressure Chamber

    Considerations of Pressure Sensors:

    Contact-Based Measurement: Pressure sensors require direct contact with the liquid. However, because the PTLevel is constructed with chemical-resistant materials and designed to withstand ice, snow, heat, and rain, you can confidently navigate any challenging liquid-level monitoring situation.

    Installation Challenges: Depending on the application, installing pressure sensors may prove more complex than ultrasonic sensors, especially in scenarios where establishing physical contact with the liquid poses challenges. However, the PTLevel has eased this challenge by being designed for easy installation. Just connect the air pressure tubing to the pressure chamber and lower the pressure chamber into your liquid.

    Ultrasonic Sensors:

    Ultrasonic sensors utilize sound waves to measure the distance to the liquid surface. They are most known for their non-contact nature and are commonly employed in applications like wastewater monitoring. Here are some key points to consider:

    Advantages of Ultrasonic Sensors:

    Non-Contact Measurement: Ultrasonic sensors excel in scenarios where non-contact measurement is essential, preventing contamination of the liquid or potential damage to the sensor.

    Easy Installation: These sensors are generally easier to install compared to pressure sensors, as they don’t require direct contact with the liquid.

    Considerations of Ultrasonic Sensors:

    Environmental Factors: Ultrasonic sensors may face difficulty in environments with high levels of dust, humidity, temperature fluctuations, or freezing temperatures. These factors can impact the accuracy of measurements. As soon as the sensor gets covered in dust, condensation, or frost, it can no longer provide accurate measurements.

    Cost: While ultrasonic sensors offer unique advantages, they can be more expensive than pressure sensors, which may influence the decision-making process.

    Maintenance: Dust, dirt, frost, and condensation or other debris can accumulate on the sensor, affecting the sensor’s performance. Regularly clean the sensor with a soft, lint-free cloth to ensure clear transmission and reception of ultrasonic signals.

    Choosing the Right Sensor:

    Ultimately, the choice between pressure and ultrasonic sensors depends on the specific requirements of the application. Factors such as accuracy, cost, installation complexity, and environmental conditions play a pivotal role in this decision-making process. Careful consideration of these factors will ensure that the selected sensor aligns perfectly with the goals of the liquid measurement system.

    In conclusion, both pressure and ultrasonic sensors have their merits, and the optimal choice hinges on the unique demands of the application at hand. But we hope we’ve convinced you, the PTLevel is the perfect solution (with a 30-day money-back guarantee).

    The PTLevel; Liquid Level Monitor with Pressure Sensor

    PTLevel in ice storm

    Weather Resistant

    Every PTLevel device is meticulously crafted to thrive in outdoor environments. Designed for -40°C to 85°C temperature range and handle snow, ice, or rain. And with using innovative Lora technology, 1 km or more can be achieved depending on the environment.

    Tank Level History

    Accurate

    Leveraging a state-of-the-art 0-100kPa pressure sensor and cutting-edge circuitry and software, the PTLevel ensures precise liquid level measurements. Enjoy peace of mind with its extended 2+ year battery life, receive timely alerts for low or high levels, and access a comprehensive liquid level history.

    PTLevel Pressure Chamber

    Cost Effective

    Starting as low as $209.99 USD with no annual fees (for the Wired WiFi PTLevel) and $299.99 USD with no annual fees (for the Long Range Wireless PTLevel), it’s an affordable liquid measurement option! By avoiding equipment damage caused by water outages and staying informed to schedule water deliveries only when necessary, you’ll not only enhance efficiency but also realize substantial cost savings.

    Choosing a Rain Water Collection System

    rain water

    Choosing a Rain Water Collection System

    Many of our customers harvest rain water to store it for later use, and then use our PTLevel devices to monitor their Rain Water Collection Systems. The PTLevel and Rain Water Harvesting make a great pair! However, selecting the right rain water collection system can be tricky.

    The Basics:

    Rain Water Harvesting
    Rain Water Collection
    Rain Water Catchment
    Roof Water Collection
    and Rooftop Water Collection – they all mean the same thing. It’s the idea of collecting rain water run-off from a structure and then storing it for later use.

    Recently, rain water harvesting has had some controversy in some areas of the world. In fact, in some cities it is illegal to collect and store rainwater. In many other areas of the world there are strict rules about collection. Make sure to research the rules and regulations for your area before choosing a rain water collection system. But if Rain Water Harvesting is right for you, keep reading! And if you think the PTLevel is right for you and your water monitoring needs, find our more here.

    Benefits of Rain Water Harvesting

    -rain is free

    -rain water is generally clean (purification is needed before drinking it)

    -use your harvested rain water anytime (still follow your city rules on water restrictions, if any)

    -rainwater is actually better for your plants and landscape because it does not have chlorine or other chemicals in it

    -collecting rain water can help improve your water run-off and storm-water runoff problems

    -rain water collection systems are easy to maintain

    -typically rain water harvesting systems can be easily retrofitted to existing homes and structures with no significant investments needed

    -stored rain water can be a back-up source of water for emergencies

    -rain water harvesting can reduce the need for imported water from other communities

    -you’ve probably heard of food-miles, well rain water collection reduces your water-miles. (reduced water trucking or even water piped to your residence)

    -using rain water to replace your municipal water usage can reduce your water bill and save you money

    -and more

    Different Rain Water Harvesting Methods

    Rain Barrels

    By far the most common method, the general idea is that you install a rain barrel at a downspout to collect rain. This is an incredibly easy way to test to see if rain water harvesting is right for you. Rain barrels can be an up-cycled barrel you already have laying around or a readily-available barrel purchased from your local hardware store. Barrels are typically small and don’t take up a large footprint. However, rain barrel systems are small and usually max out at 50-100 gallons as well as can easily overflow causing runoff issues.

    “Dry” System

    Called a dry system because the downspout will “dry” between collections when the water empties into the larger tank, it is similar to a rain collection system, just bigger. This system is ideal if you need more than 50-100 gallons of water storage, or if you live in weather areas when rain is infrequent but comes in with large weather events that bring in a lot of water at once. This is again a low-cost and low-maintenance system. Locate the large water storage tank close to the structure where water is collected (such as your house).

    “Wet” System

    This is a more complex and costly system; however, if setup properly, can offer an increased water storage capacity as well as storage away from buildings. With this type of system you can also collect rain water from multiple gutters. To set up this system, start by choosing a location for your water storage tank away from your house, but ensuring it is located in an area that your gutters are higher than the tank inlet. Next you can plan, design, and then build your underground pipe system (all of your pipes and valves must be water-tight). Make sure to consult a professional to design this system efficiently and safely.


    The good news is that the PTLevel Wireless or Wired can be used with any of these systems! The PTLevel can accurately monitor your Rain Water Collection Systems with how much water you have stored, as well as track water history for up to 2 years with the premium features. The Wired WiFi PTLevel can easily be installed in tanks within WIFI range and that have access to a power outlet, and the Long Range PTLevel can be installed up to 1km from your WiFI signal!

    We would be happy to answer any questions you have about installing a PTLevel and monitoring your Rain Harvesting Collection Systems – contact us today! Please check out additional information about cisterns and tank management here.

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