Did you know that an average rooftop collects 600 gallons of water per inch of rain? Instead of letting it go to waste, you can harvest and store rainwater to lower your water bills, support your garden, and contribute to water conservation efforts.
This guide will walk you through how to build a rainwater harvesting system while avoiding common mistakes DIYers make.
Step 1: Choosing the Right Location
Choosing the right location for your rainwater harvesting system is critical for efficiency, safety, and longevity. Start by assessing your roof catchment area—metal and tile roofs provide the cleanest runoff, while asphalt shingles may require extra filtration.
Downspout positioning should maximize water collection and ensure proper flow. Consider overflow management, directing excess water away from structures to prevent damage. Placing your storage tank in a shaded area helps prevent algae growth, while higher elevations allow for gravity-fed irrigation.
Accessibility is key—tanks, filters, and diverters should be easy to reach for maintenance.
Additionally, be mindful of local regulations, as some municipalities have restrictions on water collection. Planning for future expansion can save time and money in the long run, allowing you to scale your system as needed.
Lastly, rainwater collection systems must have overflow mechanisms to handle excess rainfall. A proper drainage route prevents flooding and soil erosion.
Pro Tip: Use a high-quality downspout adapter like Aquabarrel’s adjustable universal downspout adapter for better water flow.
Step 2: Installing Gutters and Downspouts
Your rain collection efficiency depends on clean and functional gutters. Remove debris, leaves, and dirt.
Begin by selecting high-quality materials such as aluminum or stainless steel to ensure durability.
Position the gutters at a slight downward slope to encourage smooth water flow toward the downspouts.
Regular cleaning and maintenance are necessary to prevent clogs caused by leaves, dirt, and debris. Installing gutter guards can help reduce maintenance efforts and keep the system functioning optimally.
Downspouts should be securely fastened and directed toward your rainwater storage system. Using an adjustable universal downspout adapter, like those from Aquabarrel, ensures a seamless connection to rain barrels or storage tanks.
Additionally, consider installing a first flush diverter, which helps remove contaminants from the initial runoff, ensuring cleaner water enters your system. Properly designed gutters and downspouts not only improve collection efficiency but also reduce overflow risks and potential damage to your property
Step 3: Adding a First Flush Diverter
A first flush diverter ensures cleaner water by diverting the first flow of rainwater away from your storage tank. This initial runoff often contains dust, dirt, pollen, bird droppings, and other debris that accumulate on the roof. By allowing the first portion of rainfall to be discarded, a first flush diverter significantly improves water quality.
Installing a first flush system is straightforward and can be easily integrated into your downspout setup. Aquabarrel offers high-quality first-flush diverters designed to improve filtration efficiency.
Regular maintenance, such as cleaning out accumulated debris, ensures continued performance. By incorporating a first flush diverter into your rainwater collection system, you help reduce contamination and enhance the usability of your stored water for irrigation, household use, or potable applications with additional filtration.
Can I drink harvested rainwater?
Rainwater is not immediately potable but can be filtered and treated safely.
Use a carbon filter or UV sterilization system for clean drinking water.
Step 4: Selecting a Storage Tank
Storage options vary based on space, budget, and intended use:
Rain Barrels (50-300 gallons): Ideal for small gardens.
Storage Tanks (1,000-5,000 gallons): Great for larger irrigation needs.
Underground Cisterns (10,000+ gallons): Best for long-term storage.
If it’s too small, you risk running out of water during dry months. If it’s too large, you may overspend on unnecessary storage capacity. Consider your water demand, roof collection area, and average rainfall to determine the right tank size. A properly sized tank ensures optimal efficiency and meets your household or irrigation needs without excessive waste.
For those unsure about the best option, we wrote an article about calculating rainwater harvesting tank size.
Step 5: Filtration & Water Treatment
A multi-layered filtration system helps remove sediments, organic matter, and harmful microorganisms. Mesh screens at the collection points prevent large debris from entering the system, while carbon filters enhance taste and remove chemical contaminants.
A UV sterilization unit or a chlorine treatment system effectively kills bacteria and viruses for those considering potable use. Additionally, regular maintenance and cleaning of filters and tanks prolongs system longevity and efficiency.
To maintain water quality, install:
Mesh Screens: Block debris and insects.
Carbon Filters: Remove odors and contaminants.
UV or Chlorine Treatment: Purify water for potable use.
Pro Tip: Store water in a shaded area to prevent algae growth.
Preventing Mosquito Infestation
Mosquitoes are attracted to stagnant water, making rainwater harvesting systems a potential breeding ground if not properly maintained. To prevent infestations, ensure that all collection points have tight mesh screens to block mosquito entry. Regularly inspect and clean gutters, downspouts, and tanks to eliminate standing water where larvae can develop. Adding a few drops of vegetable or mineral oil to the water surface creates a thin film that suffocates mosquito larvae without harming plants.
Another effective strategy is to install mosquito dunks, which contain Bacillus thuringiensis israelensis (BTI), a natural bacterium that kills mosquito larvae but is safe for humans, pets, and wildlife. Keeping water circulating with a small pump or aeration system also helps deter mosquitoes by disrupting their breeding environment.
Preventing System Overflow
Installing an overflow pipe that directs excess water away from structures and into a safe drainage area, such as a garden bed or soakaway pit, can help manage surplus rainwater effectively.
Ensure your tank is appropriately sized based on rainfall patterns and usage needs to minimize excessive overflow. Adding a float valve or level indicator allows you to monitor water levels and take preventive action before reaching capacity. Regularly check and maintain your system to ensure all overflow components function efficiently.
Why Choose Aquabarrel for Your Rainwater Harvesting Needs?
Aquabarrel has 20+ years of experience in rainwater collection solutions. Their high-quality downspout adapters, first flush diverters, and filtration systems make DIY rainwater harvesting easier and more efficient. Instead of relying on generic products from Amazon, trust a small business that prioritizes customer service and industry expertise.
Building a rainwater harvesting system is simple, cost-effective, and environmentally friendly. Whether you want to reduce water bills, water your garden, or store emergency water, following these steps ensures success.
For expert-recommended rainwater harvesting products, visit our website and start collecting rainwater the right way!