A Black Friday "deal" is often a normal price next to an inflated list price. Here a under-sink reverse osmosis system only counts as on sale when its checked price is at least 15% below its own typical price over the last 90 days, from our price history. The best-rated models are listed too, since many are good value without a sale. See deals in every category.
On sale now
No under-sink reverse osmosis system rated 3.8 or higher is 15% or more below its typical price at the last price check (November 2, 2026). Prices are rechecked through the sales; this list updates when one drops. See the recent price changes.
Best buys at their normal price
The top-rated models in each type. A sale on one of these is worth more than a big discount on a weaker model.
Best Tankless Reverse Osmosis Systems
- Waterdrop G5P500A#1 of 15Full review
For a buyer on a budget who still wants certified RO water with minerals added back.
Amazon $229.99$229.99500 gpd2:1$125 a year - Waterdrop G5P700A#2 of 15Full review
For a buyer who wants certified RO with mineralized water and a smart faucet for around $300.
Amazon $309.99$309.99700 gpd2:1$130 a year - Delta Clarifi Tankless RO#3 of 15Full review
For a household that wants a broadly certified tankless system with low running costs and a long warranty. Budget buyers can get similar output for less.
Amazon $799$799600 gpd2:1$201 a year
Best Reverse Osmosis Systems With a Tank
- APEC ROES-100#1 of 14Full review
For families who want a certified tank RO system with more output and a faster pour than entry models, at a low price.
Amazon $199.99$199.99100 gpd1:1$95 a year - iSpring RCC7#2 of 14Full review
For a household that wants proven, certified RO water at a low price and does not mind a tank under the sink. Filters cost little and are easy to find.
Amazon $188.09$188.0975 gpd-$63 a year - APEC RO-90#3 of 14Full review
For buyers who want a certified, low-maintenance tank RO system with long-lasting filters.
Amazon $209.99$209.9990 gpd-$73 a year
Prices were last checked November 2, 2026 and are subject to change; the price and availability shown by the retailer at the time of purchase apply.