Water is an invaluable resource, and as climate patterns shift and water prices rise, homeowners, farmers, and businesses alike are looking for sustainable alternatives. That’s where rainwater cisterns come in.
As someone who’s spent the past two decades immersed in rainwater harvesting, I can tell you firsthand that investing in a cistern system is a smart move for anyone serious about reducing their reliance on municipal water and lowering their environmental footprint.
What is a Rainwater Cistern?
A rainwater cistern is a large storage system designed to collect and store rainwater, typically from rooftops. Unlike a simple rain barrel, which holds a limited amount of water, cisterns can store thousands of gallons, making them ideal for irrigation, outdoor water use, and even emergency water supply.
Difference Between Cisterns and Rain Barrels
Rain barrels are small-scale storage solutions, usually holding between 50 and 100 gallons of water. They’re great for watering gardens but aren’t sufficient for large-scale use. Cisterns, on the other hand, can hold anywhere from 500 to 50,000 gallons, making them suitable for more extensive applications, such as supplying water to greenhouses, livestock, and even entire households when properly filtered.
I like to call Cisterns grown up rain barrels.
Benefits of Using Rainwater Cisterns
Reducing Water Bills & Utility Costs
One of the most immediate benefits of rainwater harvesting is the reduction in water bills. For homeowners, using rainwater for irrigation, laundry, and even toilet flushing can cut water costs significantly.
Businesses and homeowners that implement large-scale rainwater collection can see even more substantial savings, particularly in industries that use water for cooling, cleaning, or manufacturing.
Water Security During Droughts & Emergencies
Relying solely on municipal water supplies is becoming increasingly risky as climate change intensifies droughts. Harvested rainwater serves as a buffer, ensuring that homeowners and businesses have access to water even when restrictions or shortages occur. In areas with unreliable infrastructure, having a personal rainwater supply can be a game-changer.
Improving Water Quality for Plants & Appliances
Many people don’t realize that rainwater is naturally soft, meaning it lacks the minerals found in municipal water that can lead to scale buildup in pipes and appliances. This makes rainwater ideal for irrigation, as it promotes healthier plant growth without chlorine or fluoride. Additionally, using soft rainwater in washing machines and dishwashers extends the lifespan of these appliances by preventing mineral buildup.
Creating Sustainable Food Systems
Harvested rainwater is excellent for hydroponics, aquaponics, and traditional gardening. By using natural, untreated water, urban farms and backyard gardeners can grow food without concerns about chemical additives that may be present in tap water. A self-sustaining water source encourages local food production, reducing dependence on industrial agriculture and the long supply chains that come with it.
How to Install a Rainwater Cistern
Step 1: Assess Your Property
Determine your catchment area by calculating how much rainfall your roof receives. Ensure your gutters and downspouts are in good condition to channel water effectively.
Step 2: Choose the Right Size
Cistern size often depends on budget rather than rainfall availability. A 650-gallon cistern, for example, can fill from a single storm. The key is to match your daily water needs with your storage capacity.
Estimate Annual Water Needs: Combine all your expected water uses (household, irrigation, livestock, etc.) to get an annual total. For instance, a family of four may use 50,000 gallons annually for indoor and outdoor purposes.
Calculate Potential Collection: Use the formula above to determine how much water your roof can capture in a year.
Account for Storage Loss: Evaporation, system inefficiencies, and leaks can reduce storage. Estimate a 10-15% loss to avoid undersizing your cistern.
Choose the Right Capacity: Compare your needs against your collection potential and adjust for any gaps. Always choose a cistern slightly larger than your calculated need to handle unexpected events.
Cistern Size Ranges:
500-1,000 Gallons: Ideal for small households or single-purpose uses like garden irrigation or topping off a pool.
2,500-5,000 Gallons: Perfect for medium-sized households relying on rainwater for potable and non-potable needs.
10,000+ Gallons: Designed for farms or commercial operations, these cisterns handle significant water needs and provide the most resilience during dry periods.
A basic 650-gallon above-ground system can cost between $500 and $1,500, while a larger, professionally installed underground system may exceed $10,000.
Step 3: Prepare the Base
A stable base—such as gravel, concrete, or cement blocks—prevents shifting and damage over time. A solid foundation is crucial to maintaining your cistern's longevity and structural integrity. Gravel provides excellent drainage, reducing the risk of water pooling around the base, which could lead to erosion or instability.
Concrete slabs offer a firm, level surface, ideal for larger, heavier cisterns. Cement blocks can be strategically arranged to elevate the system, helping to facilitate gravity-fed water flow. Whichever base material you choose, ensure that it is level and compacted to prevent tilting or settling over time.
Step 4: Position the Cistern
If possible, place the cistern downhill for a gravity-fed system, as this allows for a natural flow of water without the need for mechanical assistance. A well-positioned cistern reduces the need for pumps and energy consumption, making your system more efficient and sustainable.
If a downhill placement isn’t feasible, a pump will be necessary to move the water where it’s needed. Consider installing the cistern near existing water infrastructure, such as irrigation lines or garden beds, to optimize water distribution and minimize unnecessary piping and connections.
Step 5: Manage Overflow
Installing an overflow valve ensures that excess water is safely directed away from your house’s foundation, preventing soil erosion and potential structural issues. Ideally, overflow should be directed to a designated drainage area, a rain garden, or even an additional storage container.
Using a perforated pipe or a French drain can help disperse water more effectively.
Regularly inspecting and maintaining the overflow system ensures that it functions properly, preventing blockages that could lead to unintended flooding or damage.
Maintenance Best Practices
Cleaning and Filtration
Annual cleaning of the interior walls helps prevent algae and sediment buildup. Using a first-flush diverter keeps debris and contaminants from entering the tank.
Preventing Algae Growth
Keeping the cistern out of direct sunlight and using opaque materials helps prevent algae from forming.
Winterization
Disconnect hoses and pumps before freezing temperatures set in. While most cisterns only freeze at the surface, winterizing your cistern ensures longevity.
Financial Feasibility
Cistern systems can have long payback periods, often exceeding 50 years. However, they become cost-effective in scenarios like greenhouse irrigation, off-grid homes, or when municipal water costs are high.
Pro Tip: Many homeowners use IBC totes for budget-friendly cisterns. Gravity-fed systems and homemade first-flush diverters also help reduce costs.
Is Cistern Water Safe To Drink?
Using a cistern for water storage is an age-old practice that remains highly relevant today. While cisterns provide an eco-friendly way to capture and store rainwater, ensuring the water is safe for drinking requires careful system design and consistent upkeep. Contaminants like bacteria, viruses, and chemical pollutants can enter the system through the collection surface, plumbing, or the cistern itself. Proper filtration, disinfection, and regular maintenance are essential to making cistern water safe for human consumption.
To minimize risks, homeowners should invest in a well-designed system that includes a first-flush diverter, sediment filters, and a reliable disinfection method such as UV sterilization or chlorine treatment.
Keeping the cistern covered prevents contamination from debris and pests, while periodic cleaning ensures biofilm and sediment buildup don’t compromise water quality.
Are You Ready For A Cistern?
Investing in a rainwater cistern is a long-term commitment that offers both environmental and financial benefits. Whether you’re a gardener looking to reduce water bills, a homesteader aiming for self-sufficiency, or a business owner seeking sustainable solutions, a well-maintained cistern system can serve your needs for years to come.
At Aquabarrel, we provide high-quality cistern components, downspout adapters, and first-flush diverters designed to maximize your rainwater harvesting efforts. If you’re ready to take control of your water use, check out our range of products at Aquabarrel.com and start your journey toward sustainable water management today.