← Technology WikiGPD (Gallons Per Day) — Water Flow Rating
GPD (gallons per day) is the standard flow rating for RO membranes — an 800 GPD membrane can produce up to 800 gallons of purified water per day under standard test conditions.
How it works
- Rated under standard conditions (typically 77F, specific feed pressure and TDS) — real-world output is usually 65–85% of rated.
- Common ratings: 50/75/100 GPD (home), 200/400/600/800 GPD (high-flow home and light commercial).
- Higher GPD = larger membrane (3012 vs 1812) + bigger booster pump + higher drain ratio.
- GPD says nothing about water QUALITY — always read it together with the rejection rate.
Key specifications
| Home standard | 50–100 GPD |
| High-flow home | 400–800 GPD |
| Real-world output | 65–85% of rated |
| Test conditions | 77F, standard pressure/TDS |
What buyers and QC should check
- For B2B: define the acceptance test (temperature, pressure, feed TDS) in the contract — otherwise GPD disputes are inevitable.
- Don't oversize blindly: an 800 GPD system in a 2-person household wastes water and money.
Free one-page QC checklist (PDF)
The buyer checks from this entry, condensed for the factory floor or the inspection. No signup needed.
Download free PDF checklistCommon questions
Is a higher GPD always better?
No. Match GPD to actual daily use. Oversized membranes cost more, need bigger pumps, and waste more water per gallon produced.
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