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!

    Common Signs Your Septic Tank Needs Attention

    Holding Tank Septic Tank Monitor Alarm

    Common Signs Your Septic Tank Needs Maintenance

    First, what is a Septic Tank, and how do you know when it needs maintenance?

    When you’re septic tank needs attention, you need to act fast with maintenance or repair to prevent costly, and stinky, problems. A septic tank is an underground, watertight container designed to treat and manage wastewater from homes or buildings that are not connected to a municipal sewer system. It serves as a critical component of a septic system, which safely processes and disposes of wastewater on-site.

    septic bed, also known as a leach fielddrain field, or absorption field, is a critical part of a septic system that works in conjunction with the septic tank. It is an area of soil or gravel where the treated wastewater (effluent) from the septic tank is dispersed and naturally filtered before being absorbed into the ground.

    Signs your Septic System Needs Maintenance

    Keep reading to the end of the article to find out what to do about each of these problems.

    Slow drains in home

    Gurgling sounds from pipes

    Foul odors around tanks or drains

    Holding Tank Septic Tank Monitor Alarm

    Standing water or soggy soil

    Unusual grass growth

    Frequent toilet backups

    How does a Septic Tank Work?

    Wastewater Flow

    Wastewater from toilets, sinks, showers, and appliances flows into the septic tank. This includes both solid and liquid waste.

    Separation of Solids and Liquids

    Inside the tank, the waste separates into three layers:

    Scum: Lighter materials (like oils and grease) float to the top.

    Effluent: The liquid middle layer, which contains water and dissolved waste.

    Sludge: Heavier solids sink to the bottom.

    Natural Bacterial Breakdown

    Bacteria in the tank break down organic material, reducing the volume of solids over time.

    Effluent Discharge

    The liquid effluent flows out of the tank into a drain field (or leach field), where it is naturally filtered and absorbed into the soil.

    Solid Waste Accumulation

    Over time, sludge and scum build up and must be pumped out regularly to maintain the system’s functionality.

    You can monitor your septic tank levels and your holding tank levels, and get alarms to let you know if there’s a problem, before it’s a big problem?

    • low level alerts
    • high level alerts
    • history graphs
    • temperature tracking

    How does a Septic Bed work?

    Effluent Flow

    After the septic tank separates solids from liquids, the liquid effluent flows into the septic bed through a network of perforated pipes.

    Distribution of Wastewater

    The pipes in the bed evenly distribute the effluent into a gravel-filled trench or a system of chambers.

    Natural Filtration

    As the effluent seeps into the surrounding soil, it is filtered by natural processes. Microorganisms in the soil break down any remaining organic material, pathogens, and nutrients.

    Groundwater Protection

    Once filtered, the clean water continues to percolate through the soil layers, eventually recharging the groundwater without harmful contaminants.

    So now that you understand how the septic system works, let’s dig into common signs you’ll see when your septic tank needs attention, and how a monitoring system can help!

    Lush, patchy, soggy grass around your septic bed is…. bad!

    Because there is extra nitrogen and phosphorus that is naturally found in human and animal waste, when you start seeing lush, patchy, or soggy areas around your septic bed it could mean your septic system is failing.

    Leach lines are commonly made of PVC pipe, and they’re placed into trenches filled with gravel and sand, which help treat the wastewater. The PVC pipes are drilled with small holes so the wastewater can drain out of the pipes and into the surrounding material.

    Lush, patchy, and soggy grass around your septic bed may be signs your septic systems has problems.

    Signs Your Septic Tank Needs Maintenance

    Slow Drains in Your Home

    Description: Water drains sluggishly in sinks, showers, or toilets.

    Causes: A full tank or blockages in the system.

    Monitoring Solution: A monitoring system can detect high levels before slow drainage becomes noticeable.

    Gurgling Sounds from Pipes

    Description: Unusual noises when water drains or the toilet flushes.

    Causes: Air trapped in pipes due to clogs or rising levels in the tank.

    Monitoring Solution: Alert systems can notify you of rising water levels.

    Foul Odors Around the Tank or Drains

    Description: Persistent sewage smells inside or outside your home.

    Causes: Overflowing tank or leaks in the system.

    Monitoring Solution: Monitoring can identify issues before odors develop. With a monitoring system like the PTLevel, you can view your levels anytime, view charts of the history of the levels, and even get SMS and email alerts if your level gets too high or too low.

    Standing Water or Soggy Soil

    Description: Water pooling near the drain field or septic tank.

    Causes: Tank overflow or system failure.

    Monitoring Solution: Early detection of high water levels helps prevent surface leaks

    Lush, Unusual Grass Growth

    Description: Areas of grass near the septic tank appear greener and grow faster.

    Causes: Leaking tank releasing nutrients into the soil.

    Monitoring Solution: Alerts for leaks or unusual water level changes.

    Frequent Toilet Backups

    Description: Toilets that don’t flush properly or back up regularly.

    Causes: A full tank or clogged pipes.

    Monitoring Solution: Real-time water level tracking prevents overflow situations.

    Key Features of the PTLevel for Septic Tank Monitoring

    WiFi Connectivity

    Real-time Alerts: Receive instant notifications on your smartphone when the tank’s water levels are too high or too low.

    Remote Access: Monitor your septic tank from anywhere, eliminating the need for physical inspections.

    Cloud-Based Data Storage: Access historical data to analyze trends and spot patterns in water usage.

    Long-Range Capabilities

    Ideal for Remote Locations: Works well even when the septic tank is far from the main building, making it perfect for rural properties or farms.

    Strong Signal Strength: Ensures reliable communication between the PTLevel device and your network, even in challenging environments.

    Low Power Consumption

    Long Battery Life: Operates for over two years on a single battery, reducing maintenance costs and hassle.

    Sustainable and Cost-Effective: Lower energy usage supports environmentally friendly practices and keeps operating costs minimal.

    Prevents Costly Overflows and Repairs

    Early detection of rising water levels helps prevent backups and expensive system repairs.

    Improves Maintenance Scheduling

    Provides accurate data on tank usage, helping you schedule pump-outs at the right time.

    User-Friendly Installation

    Easy to set up without requiring professional assistance, saving both time and money.

    Compatibility with Various Septic Systems

    Works with different tank sizes and designs, making it versatile for homeowners, businesses, and farms.

    PTLevel Septic Tank Monitor Holding Tank monitor
    Holding Tank Septic Tank Monitor Alarm

    Subtitle for this Section

    How to clean a cistern

    Cement Cistern

    How to clean a cistern

    Whether you have a plastic or cement cistern, rain water collection system, or other water tank; consistent and regular maintenance is important to maintain clean and safe water.  We highly recommend you consider hiring a professional to clean your tank. They often have experience and tools that are just unmatched by the DIY’er.  But if you’re up for the challenge, here are some frequently asked questions about how to clean a cistern to help you tackle the job yourself!

    How to clean your cistern
    Frequently asked questions on how to clean your cistern

    Question: How often should a cistern be cleaned?

    Answer: The quick answer is, you should be cleaning your cistern yearly. But there are a variety of factors that can affect the cleanliness of a cistern. Cisterns get “dirty” for several reasons such as hauled water vs rain water collection, different climates, and the material the cistern is made out of (cement vs plastic tank). Because of these reasons, cisterns will need to be cleaned more or less often.

    Generally, if you only have water hauled to you and you are not collecting any water that isn’t already purified in some way, your cistern will need to be cleaned less often, likely every 2-3 years. This also depends on local contaminants and the material your cistern is made out of.

    If you are collecting rain water, your cistern should be cleaned more often. Usually cleaning is recommended yearly but you may want to clean the cistern more frequently.

    Different climates can also affect bacteria levels, sediments, and other water contaminants. Since there are too many climates to mention, it is best to do your own research on your climate to determine what contaminants may be affecting your water.

    And finally, the material your cistern is made out of may also affect the frequency of a needed cistern cleaning. A cement cistern is porous, and will likely contribute to more sediment and sludge. A plastic tank will still need to be cleaned regularly and may be more prone to algae build up.

    Always clean your cistern if the water starts to look, smell, or taste different.

    Question: How do you clean a cistern?

    Answer: The Centers for Disease Control and Prevention has a written a great article on the subject. Please visit here for their maintenance advice on cisterns and other rain catchment systems.

    Step 1. Remove all debris and water from the cistern as well as debris from water collection points (eg if you collect rain water, clean your eaves troughs). This step applies to all cisterns, wells, rain water collection systems, and other liquid tanks.

    Step 2. For cement cisterns, scrub the inside of the cistern with a stiff brush and a solution of 1 cup of bleach mixed with 10 gallons of water. Since bleach isn’t recommended for plastic cisterns, contact the manufacturer of your plastic cistern, or read the instruction manual on what your manufacturer recommends. Be mindful of your air quality when you’re in a cistern! Breathing in fumes from chemicals can be dangerous, and sometimes even fatal. Always read and follow all instructions on the materials you are using.

    Step 3. Rinse cistern with clean, safe water, and then drain. If you still smell bleach, rinse the tank once or twice more.

    Step 4. Refill the cistern with clean, safe water.

    When it doubt, reach out to a professional to have your cistern cleaned. Cistern cleaning professionals have the tools, experience, and knowledge to do a great job for you! They can often use a pressure washer, reducing the need for chemicals as well as use a wet vacuum to suck out all debris and sludge. The professionals will inspect your cistern for cracks and other defects. Go to Google Maps, and then type in “cistern cleaners near me” to find some local providers.

    Question: Can I use bleach in my cistern?

    Answer: If you have a cement cistern, bleach is often the recommended chemical to use for cleaning, and sometimes even maintaining clean water. You can do your own research on whether you feel like bleach is the right solution for you, but here are the recommended solutions:

    For cleaning: 1 cup of bleach per 10 gallons of water
    For maintenance: 1 tablespoon of 5%-8.25% liquid bleach for every 100 gallons of water

    Bleach is not recommended for plastic cisterns or tanks.

    Question: Do all cisterns need to be cleaned?

    Answer: Yes. Cisterns are designed to hold standing water and whenever there is standing water there is opportunity for bacteria growth and dirt and debris to collect. Also, wildlife will often find a way to get into water systems which can create even more risk for bacteria growth and debris that you don’t want to drink or use.

    We hope some of these questions and answers were helpful to you.  If you’re looking for a water level monitoring solution, please check out our products page here.

    How often should I test the water in my cistern?

    It is recommended that you test  the water in your cistern seasonally for routine monitoring. You should also test the water any time the water quality changes (for example if the water starts to look, smell, or taste different).

    What tools do I need to clean my cistern?

    You may want the following tools and equipment to make the process of cleaning your cistern easier. Ladder, rubber boots (or hip waders if you have them), pump, soft scrubbing brushes, pressure washer, wet/dry ShopVac, flat shovel, buckets, bleach or chlorine, and rubber gloves.

    You may also want to consider having patches on-hand for this process (concrete patch/hydraulic cement for cement cisterns) . If you come across any cracks or leaks in your cistern, this will be a great time to repair those holes!

    How do I calculate how much water is in my cistern?

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