The Cost of a Potable Rainwater Harvesting System
- Deb
- Apr 29
- 5 min read
Updated: May 2
Disclosure: Some of the links on this page are affiliate links, and I may earn a commission if you click through and make a purchase.
Is setting up a rainwater collection system for your entire home and garden cheap? No! Sure, you can save money with some DIY parts and pieces, but the upfront cost of a potable rainwater harvesting system can be significant depending on its size and storage capacity. That said, as water scarcity becomes a growing concern in many parts of the world and with so many people living in rural areas where municipal water isn't an option, more homeowners (like us!) are turning to sustainable solutions like rainwater harvesting. While this practice has long been used for irrigation, it’s increasingly being adopted for household use—including potable (drinkable) water.
We installed a building-code-compliant potable rainwater harvesting system that supplies all our household and gardening needs, and in this post, I’ll use our own setup as an example to share what it really cost us to get it up and running.
I’ll break down the real costs involved, explore what you need for a fully functional system, and look at why this investment could pay off in more ways than one.
Why Choose a Potable Rainwater Harvesting System?
For many homeowners, collecting rainwater is more than saving on water bills—it's about independence, sustainability, and securing a reliable water source. A potable system allows you to use harvested rainwater for drinking, cooking, bathing, and all other household needs, not just for gardening or flushing toilets.
This makes it ideal for:
Off-grid homes
Rural properties with unreliable well or municipal water
Eco-conscious households looking to reduce their environmental impact
Preppers and self-reliant lifestyles
But turning rainwater into safe, drinkable water involves more components and more cost than a simple barrel under a gutter.
Components of a Potable Rainwater Harvesting System
Before diving into the numbers, let’s look at what’s included in a full system designed for potable use:
Catchment Surface: Typically your home’s roof. Metal roofing is preferred because it doesn’t leach harmful chemicals and is easier to clean.
Gutters and Downspouts: These channel rainwater from the roof into your storage tanks.
First-Flush Diverter: Removes the initial dirty runoff from the roof before it reaches your storage tank.
Storage Tanks: These range from 500 gallons to over 10,000 gallons, depending on your usage and rainfall. Materials include plastic, fiberglass, or concrete.
Filtration System:
Sediment filters
Activated carbon filters
UV purification or reverse osmosis systems for disinfection
Pumps and Pressure Tanks: To deliver water from the tank to your taps at usable pressure.
Backup Systems (optional): Integration with well water or city water in case of drought.
Each of these components adds to the overall cost—but also to the system's reliability and safety.
How Much Does a Potable Rainwater Harvesting System Cost?
The cost can vary widely based on location, system size, and whether you install it yourself or hire professionals. Here’s a general breakdown:
Component | Estimated Cost Range |
Gutters and Downspouts | $500 – $2,000 |
First Flush Diverters | $100 – $300 |
Storage Tanks (2,500–15,000 gallons) | $1,000 – $10,000+ |
Filtration System | $1,000 – $3,000 |
UV or RO Disinfection | $800 – $2,000 |
Pump and Pressure System | $700 – $2,500 |
Installation Labor | $2,000 – $10,000+ |
Permits & Engineering | $300 – $2,000 |
Total Estimated Cost | $6,400 – $31,800+ |
These are ballpark figures, and actual costs can go higher or lower depending on specific needs, climate, and regional construction costs.
For example, if you’re in a dry climate, you may need to invest in larger tanks to get through long dry periods. Conversely, in wetter areas, you can downsize your tank and save significantly.
Here is a table similar to the one above with costs for our own rainwater harvesting system here in Northern Arizona:
Component | Our cost (2021/22) |
Gutters and downspouts on garage/shop, installed | $2,200 |
Gutters, downspouts, and first flushes on house, installed | $2,890 |
(3) 5,000-gallon cisterns plus delivery (CA to AZ) | $10,174 |
Filtration system (US Water Systems) | $300 |
Quantum disinfection system (US Water Systems) | $500 |
$900 | |
Excavation and installation for cisterns, trenching for water lines | $2,300 |
Permitting | Included in permit cost for home construction |
Total Cost | $19,264 |
Want to know more about how our system is working out? See: Rainwater Harvesting in Arizona: How We Live Off the Rain in the High Desert.
Real-World Considerations
1. Maintenance and Upkeep
Even the best system requires regular maintenance:
Cleaning or replacing filters and replacing UV bulbs (if you have that type of disinfection)
Inspecting gutters and diverters
Tank cleaning
Testing water quality periodically
Annual maintenance costs can potentially range from $100 to $500, especially if you hire someone to service your system and have to purchase new filters.
2. Permits and Codes
If your system is for potable use and part of new construction, you’ll likely need to comply with local building codes and health regulations. Some jurisdictions require inspections, engineered plans, or certifications for filtration systems.
Make sure to check with your local health department or building authority before installing.
3. DIY vs. Professional Installation
A DIY installation can significantly lower costs, especially if you’re handy and already have some infrastructure and tools and equipment. But potable systems have stricter safety requirements, so hiring a professional can ensure everything is up to code—and safe to drink.
Is It Worth the Investment?
While the upfront cost of a potable rainwater harvesting system can be significant, there are many long-term benefits:
Lower water Bills or no water bills: In some areas, municipal water is expensive, and the savings can add up quickly.
Water security: Particularly important in drought-prone or wildfire-prone regions.
Environmental impact: Reduces reliance on groundwater and centralized water systems.
Increased property value: A well-installed system can be a strong selling point for eco-conscious buyers.
And it's satisfying, too!
Plus, many states and municipalities offer rebates or tax incentives for installing rainwater harvesting systems, especially if they're designed to reduce stormwater runoff or supplement municipal supply.
Final Thoughts
Investing in a potable rainwater harvesting system isn’t just a lifestyle choice—it’s a long-term investment in resilience, sustainability, and health. Whether you’re off-grid, preparing for emergencies, or just want cleaner, more sustainable water, a well-designed system can provide all your household water needs, including safe, drinkable water year-round.
If you’re considering making the switch, start by assessing your water usage, roof size, and rainfall. Then consult with professionals or experienced DIYers to design a system that meets your needs—and your budget. Questions about the costs of a potable rainwater harvesting system for your home? Please leave them in the comments.
Written by Deb Kingsbury
Living on a 36-acre off-grid property in northern Arizona, Deb and her husband Jeremy embrace sustainable living through solar power, rainwater harvesting, and a passive solar home built with recycled polystyrene block. A freelance writer and editor, Deb grows food in raised beds and a greenhouse and is an avid hiker and backpacker. A long-time search & rescue volunteer, she has published two novels and previously homesteaded on the East Coast.
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