How much water does a reverse osmosis system waste?
The reverse osmosis systems we track send between 0.25 and 3.03 gallons to the drain for each gallon of filtered water (median 0.5, across 24 systems that publish it; lower is better). For 2 people drinking and cooking with it, that is about 102 gallons a year, roughly $2.15 of water and sewer. For comparison, EPA estimates a typical reverse osmosis unit sends at least 5 gallons to the drain per gallon treated, and WaterSense-labeled models no more than 2.3.
Drain water by system, for 2 people
| System | Pure to drain | Drain gallons a year |
|---|---|---|
| SimPure Y7P-BW | 4:1 | 51 |
| AquaTru Classic | 3:1 | 68 |
| Bluevua ROPOT-Lite | 3:1 | 68 |
| Waterdrop G3P800 | 3:1 | 68 |
| Waterdrop K19-H | 3:1 | 68 |
| Waterdrop X16 | 3:1 | 68 |
| iSpring RCD100 | 2.5:1 | 82 |
| APEC ROTL-A1000 | 2:1 | 102 |
| Bluevua RO100ROPOT | 2:1 | 102 |
| Frizzlife PD600-TAM3 | 2:1 | 102 |
| Frizzlife PD800-TAM4 | 2:1 | 102 |
| iSpring RO500AK-BN | 2:1 | 102 |
| Waterdrop D6 | 2:1 | 102 |
| Waterdrop G2P600 | 2:1 | 102 |
| Waterdrop G3P600 | 2:1 | 102 |
| A. O. Smith Direct Flow RO AOS-DFRO800 | 1.78:1 | 115 |
| AquaTru Carafe | 1.7:1 | 120 |
| iSpring RCC7P-AK | 1.5:1 | 136 |
| SimPure T1-400 | 1.5:1 | 136 |
| APEC ROES-PH75 | 0.66:1 | 310 |
| Brondell Circle RC100 | 0.5:1 | 409 |
| Aquasana SmartFlow RO | 0.38:1 | 538 |
| APEC ROES-50 | 0.34:1 | 601 |
| Express Water RO5DX | 0.33:1 | 619 |
| A. O. Smith RO with Microbial Boost AO-US-RO-MB-4000 | not published | — |
| APEC RO-PERM | not published | — |
| APEC ROES-UV75-SS | not published | — |
| iSpring RCC7AK | not published | — |
Drain gallons = filtered gallons ÷ the ratio. Filtered gallons = 2 people × 0.28 gal a day × 365. The brand's rated ratio is measured under test conditions; low water pressure raises the share sent to the drain.
Sources
Last checked 2026-10-23.