Either 50GPD, 100GPD or 400GPD are RO membrane’s water flow specification for distinction, Some people mistakenly believe these are the daily capacity. Here is how we calculate this specification:
- Make the 400GPD RO membrane filter the tap water for 5-10 minutes.
- Measure the water volume: 0.278 gallon per minute.
- Further Calculation: 0.278 gallon × 60 minutes ×24 hours ≈ 400 Gallon Per Day
Another fact is that no one can measure and state a precise amount of daily water filtration and lifespan of RO membrane. Because it’s all depending on your using habits and source water quality. Now you probabaly want to ask that why we reference 18-24 months?
The PG-400-AZ is designed for household pure drinking water demands, For a 4~5 people family, the daily capacity of pure water are 1-2 gallons. And we believe the 400gpd RO membrane will last for 18-24 months under this daily capacity. Of couse, you can get 10 even 40 gallons pure water by open the faucet constantly for hours, but long-term overload working will reduce the sevice time of RO membrane tremendously.
Even though we couldn’t announce a guarantee on all 4 filters. But if you are using the RO system only for daily drinking and the filters somehow went wrong still, we will send new filters for free. You can contact us with your order ID attached to get new replacement filters.