What is a Cistern Water System?


As more and more people move toward eco-friendly solutions, a cistern is one way some use old technology to solve a modern problem. Cisterns date back all the way to ancient Greece. These clever early water harvesting systems have been collecting and providing water to people for many centuries. Naturally, we’ve improved in the system over time, but it’s still a great way to provide a lot of relatively pure water to a home or business. What exactly is a cistern water system, and how does it work? Let’s explore an ancient innovation and how people are using it today.

What Is A Cistern

A cistern by itself is a fancy word for a rainwater collection tank. However, there’s much more to them than just placing an open container somewhere water can get inside. If you used an open-air pool style ‘tank,’ you’d immediately have issues with two significant problems. First, debris and dirt carried on the wind would get into your water supply, and second, you’d have a lot of evaporation. For a cistern to be useful, you need a large tank with a small, sealable opening. However, a tiny opening isn’t going to let much water inside. To make this a helpful collector, you need a pipe or gutter to channel in the water and a large, sloped surface to collect all that rain. In most cases, this means the roof of a house. By using the rooftop as a water collection point and moving the water down through your pipe gutter, it can land securely in the tank without needing to expose the opening and collect additional contaminants.

Can You Drink The Water From A Cistern

It would be a terrible idea to simply pour a glass of water from a cistern tank and drink it. Although rainwater is relatively clean thanks to evaporation, you can still end up with trapped air pollution in the water. Additionally, a rooftop gutter system is far from perfect. Debris and dirt that collect on the roof will naturally be washed into the cistern. For cistern water to be drinkable by modern standards, you need a way to clean out the water. Filters that remove large particles and foreign objects like tree bark are a start. After that, you’ll still need to filter the water for microorganisms, bacteria, and other less visible trouble before you can drink the water. Fortunately, with proper filtration, you can safely drink cistern collected water. Moreover, you can save energy and time by using unfiltered or less-filtered water for running toilets and watering plants.

How Does A Cistern Water System Work

Cistern water systems collect natural rainfall and channel it into a large collection container, which is often, though not always, underground. From there, the water is usually treated for health and safety. Finally, it gets pumped through pipes into your home. Essentially, this is the same as municipal plumbing, except that the water collected comes from the sky instead of wastewater pipes. Water purification and storage happen on a smaller, more personal scale. Additionally, once you’ve installed a cistern, you are responsible for your own maintenance but are otherwise ‘off the grid’ where your water needs are concerned. As Penn State describes the process, “Roof-catchment cisterns are systems used to collect and store rainwater… A system of gutters and downspouts directs the rainwater collected by the roof to the storage cistern… The cistern supplies water to the household through a standard pressurized plumbing system.”

Is A Cistern Better Than A Well

Both Cisterns and wells provide relatively stable sources of water for homes. However, there are some significant differences to consider. For example, a rain cistern system is often more expensive than drilling a well. However, you are less likely to run out of rain than groundwater over time. Plus, groundwater drillers cannot guarantee they will hit a water deposit, and you have to pay for the service regardless. A modern well is filtered naturally into the water table below, removing most impurities by traveling through many soil layers. Meanwhile, rain is filtered through evaporation. Neither system is perfect. The rain can pick up air pollution on its journey. Alternatively, up to twenty percent of private wells can become contaminated by naturally occurring radon, manganese, and other problematic chemicals like arsenic. Cisterns are more likely to harbor germs, diseases, and bacteria. However, they are also more likely to have water when you need it if installed correctly. Moreover, a cistern can be designed for any home, often without the need for on-site surveys. While it’s a close comparison, cisterns have more advantages.

Cistern Concerns

Unlike a well, a cistern tank needs maintenance. It is essential to regularly disinfect your tanks to prevent problematic microbes. Since many cisterns are in-ground, there are concerns with floodwaters. Additionally, contamination such as oil spills can ruin a cistern-based water supply. According to the CDC, “Water contaminated with fuel or toxic chemicals will not be made safe by disinfection. Do not enter the cistern. Gases and vapors can build up, creating a hazardous environment.” It would be best if you generally cleaned out a non-contaminated cistern every three to five years or more often as desired. However, if the cistern uses pre-purified, hauled water rather than a catchment system, then you may be able to clean the tank less often safely. This style of the non-catchment cistern isn’t a ‘true’ cistern but rather more like an underground water tower. Nevertheless, it may go by the same name and should be cleaned every five to ten years or as needed.

Final Thoughts

So long as you get some annual rainfall in your area, setting up a cistern is one way to use a renewable natural resource to your advantage. Whether you use an above-ground tank or one that’s dug down into the ground, a cistern can help you ensure you have plenty of water for your home. However, proper cleaning and maintenance are essential for a home cistern system, or you run the risk of bacteria, germs, and disease.

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