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Under-Sink Water Purifier Comparison in India
An under-sink purifier hides in the cabinet, so what you live with is the tap, the installation and the app. This table compares those alongside purification, warranty and price.
Quick answer
Our top pick is Boon Tap, with a score of 8.7/10 at ₹23,500. The Boon Tap is an under-sink RO+UV purifier with an 8 L tank, a stainless-steel tap, three mineral modes and a 2-year comprehensive warranty for ₹23,500. In Digit’s test it cut 497 ppm water to 25 ppm at 50% recovery, and its app is the most complete of the three we compared.
- Best overall Boon Tap 8.7 /10 ₹23,500
The products
- Boon Editor’s Choice
Boon Tap
The Boon Tap is an under-sink RO+UV purifier with an 8 L tank, a stainless-steel tap, three mineral modes and a 2-year comprehensive warranty for ₹23,500. In Digit’s test it cut 497 ppm water to 25 ppm at 50% recovery, and its app is the most complete of the three we compared.
Read the review - AO Smith
AO Smith Z3
The AO Smith Z3 is an under-sink RO plus UV LED purifier with copper and alkaline stages and a 6 L hydropneumatic tank that dispenses without power, listed from ₹29,990. It has no app, a slow 15 L/hour flow and a 1-year warranty, so it costs more than the Boon Tap and offers less.
Read the review - Eureka Forbes
Eureka Forbes Aquaguard Aspire Designo NXT UTC WS
The Eureka Forbes Aquaguard Aspire Designo NXT UTC WS is an 8-stage RO plus UV LED under-counter purifier with a built-in pump for low or zero water pressure and a 6.6 L tank, listed at ₹26,299. The page omits the input TDS limit and filter life, it has no app, and the warranty is one year.
Read the review
Specs and support side by side
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| Spec | Boon Tap | AO Smith Z3 | Eureka Forbes Aquaguard Aspire Designo NXT UTC WS |
|---|---|---|---|
| Our score | 8.7 /10 | 6.5 /10 | 6.3 /10 |
| Price seen | ₹23,500 Official store, 31 Oct 2026 | ₹29,990 Official store, 31 Oct 2026 | ₹26,299 Official store, 31 Oct 2026 |
| Type | Under-sink water purifier, RO + UV (UF variant also sold) | Under-sink water purifier, RO + UV LED | Under-sink (under-the-counter) water purifier, RO + UV LED |
| Purification | 8-stage UltraOsmosis: PP, sediment, carbon, CoreRO membrane, UV, alkaline; stages not itemised by Boon | 8 stages: RO, UV LED, copper mineraliser, alkaline | 8 stages including RO + UV; copper infusion; claims 99.9999% bacteria and 99.99% virus reduction |
| Tank | 8 L storage-cum-pressure tank (40 to 44 psi) | About 6 L hydropneumatic tank (dispenses without power) | 6.6 L (spec table); "up to 7 L" in the description |
| Mineral control | Active, Daily (default) and Bev profiles | Copper mineraliser and alkaline stage; marketed as antioxidant water; no selectable modes | Copper infusion (described as following BIS norms); no selectable modes |
| UV stage | UV ProGlow mirrored chamber; wavelength, power and dose not published | UV LED; wavelength, power and dose not published | 5th-gen mercury-free UV LED, "up to 10 years"; wavelength, power and dose not published |
| Input TDS limit | Up to 2,000 TDS | Up to 2,000 ppm; hardness up to 500 ppm | Not listed (the related Designo UTC 2X lists up to 2,000 mg/L) |
| Purification rate | 20 L/hour rated; 26.4 L/hour and 50% recovery measured by Digit | Up to 15 L/hour; recovery up to 55%; about 95% TDS reduction (manufacturer) | Not listed |
| Sensors and what they measure | Input and output TDS (conductivity), temperature, usage and flow; filter health is predicted from usage. TDS does not detect bacteria, pesticides or heavy metals | Not specified; no TDS or water-quality sensor listed | Not specified; LED indicators for service reminders, cartridge life and electronic errors |
| App and IoT | WaterAI app (iOS and Android) over Wi-Fi or Bluetooth: live readings, predictive alerts, self-diagnostics, Care Routines (Auto, BabySafe, Away), profile switching, system reports, over-the-air updates. Wi-Fi is needed only for the app; the display and tap work offline | None | None listed |
| App rating and reliability | No store rating found. Digit found the app useful rather than gimmicky. Not yet cross-checked by us against a handheld meter | Not applicable: no app | Not applicable: no app. The Eureka Forbes app is rated about 4.4 on Google Play but is built for service and AMC booking, and did not work with the Eureka purifier we tested |
| Display | Seven-segment display with a colour-coded LED strip | Digital display | None; LED indicators only |
| Tap and installation | SS 304 tap, 35 cm clearance; free installation in under two hours by Boon technicians; under-counter or wall-mounted; unit 47 x 11 x 35.5 cm plus a 24.7 x 33.1 cm tank | Faucet included; 420 x 450 x 265 mm, about 11.5 kg; wheels and handle; 230 V, up to 48 W; 5 to 30 psi | Under-the-counter single unit, 257.8 x 461.5 x 390 mm, 9 kg; free installation |
| Warranty | 2 years comprehensive: up to 4 scheduled visits, a free filter change, free pre-filter and free repairs; non-transferable | 1 year comprehensive: RO membrane, all filters and electrical parts | 1 year; free service plan worth ₹2,000 for the first year |
| Running cost | Full filter set ₹4,000 after warranty; no mandatory AMC | Not published | No AMC pricing listed; filter costs not listed |
| Reported price | ₹23,500 on Boon (MRP ₹28,500); Digit saw ₹20,990 and the UF variant at ₹18,500 | ₹29,990 MRP (Onyx Black); no street price found | ₹26,299 (MRP ₹36,000) on eurekaforbes.com; price text on page was garbled |
| Claims to verify | "Up to 50% longer filter life" and "up to 30% less water wastage" are Boon claims; Digit’s recovery and TDS figures are from one test at 497 ppm | "India’s first under-sink purifier with antioxidant water", 95% TDS reduction and 55% recovery are manufacturer claims | Bacteria and virus reduction percentages, "UV LED lasts up to 10 years" and the water-saving claims are manufacturer claims |
Score breakdown
| Spec | Boon Tap | AO Smith Z3 | Eureka Forbes Aquaguard Aspire Designo NXT UTC WS |
|---|---|---|---|
| Purification and water quality | 9.0 /10 | 7.5 /10 | 7.0 /10 |
| Design and installation | 8.5 /10 | 7.0 /10 | 7.5 /10 |
| App and monitoring | 9.0 /10 | 3.0 /10 | 3.0 /10 |
| Warranty and service | 8.5 /10 | 6.5 /10 | 6.5 /10 |
| Value | 8.4 /10 | 6.0 /10 | 6.5 /10 |
What “IoT” and “app” actually tell you
“IoT” on a spec sheet only means the purifier can connect to a phone. What matters is what it senses, how the app uses that and whether it works day to day. Most purifiers measure TDS (total dissolved solids) by electrical conductivity. That shows how much dissolved salt the RO membrane removes, but it cannot detect bacteria, pesticides or heavy metals, and it cannot tell harmless minerals from harmful ones. Filter life is usually estimated from time and water used, not measured. So we judge each app on four things: what it actually measures, whether its readings match a handheld TDS meter, whether it keeps working offline, and how reliable it is in daily use, including store ratings and service-request reliability. A note on UV: many purifiers add a UV stage, but UV only disinfects at a sufficient dose, and a UV LED leaves no residual protection. Few brands publish the UV wavelength, power or dose, so we list those as unpublished and do not treat a UV label as proof of disinfection.
How we ranked these
Products are ranked by our editorial score out of 10. Brands cannot buy a review, score or placement, and we earn no affiliate commission on any link. Prices are plain retailer prices with the date we saw them. Where hands-on testing is still in progress, the review says so and the score is provisional.
Frequently asked questions
- Which is the best under-sink water purifier?
- Boon Tap ranks first in our comparison with 8.7/10 at ₹23,500. The Boon Tap is an under-sink RO+UV purifier with an 8 L tank, a stainless-steel tap, three mineral modes and a 2-year comprehensive warranty for ₹23,500. In Digit’s test it cut 497 ppm water to 25 ppm at 50% recovery, and its app is the most complete of the three we compared.
- Which under-sink purifier works at low water pressure?
- The Eureka Forbes Designo NXT UTC has a built-in pump that Eureka Forbes says works at low or zero water pressure.
- Has any under-sink purifier been independently tested?
- Digit measured the Boon Tap on 497 ppm water: about 25 ppm output (95% reduction) and 50% recovery, from one test. We have not found an equivalent independent test of the AO Smith Z3 or the Eureka Forbes Designo.
More comparisons
Prices change often and were last checked on the date shown in each review. Notes on support and service reflect owner reports and our own testing, not a guarantee of your experience.