Our Whole-House Rainwater Filtration System
- Deb
- Jun 16
- 4 min read
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.
We’ve been living full-time on rainwater, thanks to our whole-house rainwater filtration system that delivers clean, potable water for drinking, cooking, bathing, and laundry. It’s one of the most frequently asked questions we get—what exactly do we use to filter and disinfect?
In this post, I’ll walk you through our setup, performance over the past three years, and the replacement filters we recommend. I’ve also included links so you can replicate our system if you want to.
Our Rainwater Setup (A Quick Overview)
We collect rainwater from the metal roofs on our home and garage/workshop into three 5,000-gallon tanks, with one at each end of the house and a third located on the shop. The tanks are connected below-grade, each with a shut-off valve, and the rainwater enters the house through a single pipe. (You can get more details about building a potable rainwater harvesting system like ours here.) Before entering the storage tanks, the water passes through pre-filters, including leaf filters and first-flush diverters (also known as roof washers), which you can see in the photo below.
It then enters the house using a Grundfos Scala pump located in our utility room's sump and flows through our whole-house rainwater filtration system for final purification and disinfection.
The Filtration & Disinfection Units We Use
We rely on US Water Systems' Big Blue 4.5 x 20 Dual Filtration and Pulsar Quantum Disinfection for our rainwater collection. The system includes:
Stage 1: Sediment filter
Stage 2: Carbon block filter
Stage 3: Quantum disinfection unit
This setup ensures our water is free of particulates, chemicals, and pathogens—ideal for off-grid or rural homes. It’s all plumbed after the pump and before the house’s main lines, as well as the on-demand water heater.
Three Years of Performance
While US Water System recommends changing out the filters every two years, our whole-house rainwater filtration system ran on the same filters for a full three years—and based on water test results, could have gone for longer. We did annual tests ([Brand/method]), and each time, the water passed with flying colors (which, in the case of this type of test, was deep purple). We only replaced the filters—not the housings—when the three-year mark hit, purely as a precaution.
🧪 Pro tip: Pair your system with yearly water testing to stay safe and maximize the longevity of your filters.
Replacement Filters
When the time came, we changed out:
Sediment filter: US Water 4.5" x 20" Pleated Filter Cartridge 5 Micron
Carbon filter: US Water 4.5 x 20 Carbon Block Filter | USWCB-4520-10
Quantum disinfection filter: IQ 1.0 Pulsar replacement filter cartridge
US Water Systems carries a wide variety of other replacement filters.
💡 Set reminders for testing and replacements—you’ll maximize value and safety.
What Makes This System Work for Us
✅ Low maintenance ✅ Clean, fresh-tasting water ✅ Easy-to-find replacement filters ✅ Perfect for sustainable, off-grid living with no power required
✅ Excellent customer service from US Water Systems in case of questions or problems
Installing Your Own Whole-House Rainwater Filtration System?
If you're harvesting rainwater and want clean, potable results throughout your home, a whole-house rainwater filtration system is a smart, long-term investment. Here are the parts we recommend:
This 2-stage filtration system is designed to filter the water supply for a whole house.
With just a 10-inch filter housing, you can get bacteria-free, safe, disinfected water, requiring no electricity, no chemicals, no UV bulbs that need to be disposed of properly due to their mercury content, no ballast to replace, and no carbon footprint.
Rainwater Filtration FAQ
These are some of the other common questions we get about our potable rainwater harvesting system:
1. Why is it necessary to filter and disinfect rainwater?
Even though rainwater is naturally soft and free of many chemicals, it can pick up contaminants from your roof, gutters, and storage system—including dirt, bird droppings, pollen, and bacteria. Filtration and disinfection ensure your water is safe for drinking and everyday use.
2. Can I drink rainwater without a filtration system?
We don’t recommend it. Although untreated rainwater may appear clean, it can actually contain harmful microorganisms or debris, such as bird droppings, dust and dirt from the roof, and more. A properly installed whole-house rainwater filtration system ensures the water is reliably safe for consumption.
3. How often should I replace the filters in a rainwater filtration system?
Filter replacement depends on your water usage and quality; however, a general rule of thumb is to replace filters every couple of years. We used ours for three years with great test results before replacing them. (Note that some types of filters are washable, so you can temporarily remove and clean them to extend their lifespan.)
4. Do I need electricity for a quantum disinfection system?
Nope! That’s one of the reasons we chose it. The Pulsar Quantum Disinfection unit from US Water Systems requires no electricity, no chemicals, and no UV bulbs—making it perfect for off-grid or low-energy homes like ours.
5. What kind of roof is best for potable rainwater harvesting?
Metal roofing is ideal for collecting rainwater for potable use. It's smooth, easy to clean, and less likely to leach contaminants compared to asphalt shingles or wood shake. However, other roof types can be used for a potable rainwater harvesting system as long as you have proper filtration and disinfection.
6. Can this system work in freezing climates?
Yes—with proper tank insulation and freeze-proof plumbing strategies, a whole-house rainwater filtration system can be utilized in cold climates, which we have here in Northern Arizona. We recommend burying pipes below frost depth and using insulated components where needed.
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