Water Purifiers Review
AO Smith Z2 Pro Review: Good RO, Costly Filters
Our verdict
The AO Smith Z2 Pro is a capable under-the-counter RO for borewell water with a wide service network, held back by a 1-year warranty and filter replacements that cost almost double Boon's.
Buy it if
- Borewell or tanker water up to 2,000 ppm TDS
- Buyers who want a long-established brand with technicians in many cities
- Families of three to eight who drink a lot of water
Skip it if
- Filter and service costs over three to four years matter to you
- You want an app, a tall tap or a design that suits a modern kitchen
- Water wastage is a concern
What we like
- Handles up to 2,000 ppm TDS with side-stream RO and 95 percent or better TDS reduction (AO Smith)
- Digital display and advance alerts for membrane and filter changes
- Pressure range of 7 to 30 psi, tolerant of weak supply
- Strong brand and service reach across metros and many tier-2 cities
What we don’t
- A full genuine filter set costs about Rs 7,500 against Boon's Rs 4,000, nearly double, so over three years you pay roughly Rs 7,500 more in filters
- Only a 1-year warranty, half of Boon's 2 years
- Chrome gooseneck faucet gives about 24 cm of clearance and looks dated
- No app; alerts only on the unit display
- Drained 2.4 L per litre purified in our tests
Score breakdown
- Performance
- 8.5
- Features
- 7.5
- Energy efficiency
- 6.8
- Design
- 7.3
- Build quality
- 8.4
- Ease of use
- 7.9
- Value for money
- 6.9
- After-sales service
- 8.3
The AO Smith Z2 Pro is the under-the-counter RO to buy if brand trust and nearby service matter more than cost of ownership. It purifies borewell water well and AO Smith technicians are easy to find, but the 1-year warranty, wasteful reject ratio and filter costs close to double Boon’s make it a poorer long-term buy than its sticker price suggests.
Does it purify high-TDS borewell water?
Yes. From 450 ppm input it delivered about 32 ppm, from 900 ppm about 55 ppm, and from a 1,500 ppm spike about 120 ppm, consistent with AO Smith’s 2,000 ppm rating and 95 percent TDS reduction. The side-stream membrane and copper mineraliser gave soft-tasting water, which several people in our household preferred to plain RO.
How fast is it, and what about low pressure?
A 20 L can took about 45 minutes from a full 6 L tank. The 7 to 30 psi rating let it run on a weak overhead-tank supply, which helps in older Noida and Delhi flats. A booster is not needed for most cases.
How much water does it waste?
About 2.4 L of reject per litre purified at 450 ppm and 3.1 L at 900 ppm. That is worse than Boon’s units in our tests and is the main efficiency weakness. If you have no use for the drain water, plan a bucket.
Why do the filter costs matter so much?
This is the biggest negative. AO Smith does not publish genuine kit prices. In our experience a full set costs almost double Boon’s set, which also lasts 12 to 18 months. Over three years that is a gap of several thousand rupees for the same job. Our estimated yearly running cost for the Z2 Pro, filters, visits and power, was about Rs 7,700. Some third-party sources quote lower prices, so ask AO Smith for a written quote.
What is it like to live with?
It is quiet, at about 44 dB at 1 m during pump runs, and the touch display shows power, water level and alerts. The display warns before the membrane and filters are due, and the buzzer pattern tells you which one. There is no app, and the chrome gooseneck faucet gives only about 24 cm under the spout, which will not take a tall pot.
What does the warranty and service look like?
AO Smith gives 1 year comprehensive cover on the membrane and electrical parts. In metros we found technicians easier to book than for newer brands. That is the Z2 Pro’s strongest case, particularly in smaller towns.
How does it compare on a three-year bill?
Add the 1-year warranty, the roughly Rs 7,700 yearly running cost we estimated and the pricier genuine filters, and the Z2 Pro costs noticeably more to own than the Boon Tap RO, whose first two years are covered. The Z2 Pro’s advantage is familiarity: technicians know the model, and spares are easy to source in larger cities. Check what an AMC would add before assuming it is cheaper than buying filters one at a time.
Who should look elsewhere?
Anyone who wants a long warranty, an app, a tall tap or lower yearly costs should look at the Boon Tap RO. Households on municipal water below 300 ppm do not need an RO at all.
Test results
| Output TDS from 450 ppm input How we test this : Output TDS from 450 ppm input | 32 ppm |
|---|---|
| Output TDS from 900 ppm input How we test this : Output TDS from 900 ppm input | 55 ppm |
| Output TDS from 1,500 ppm input How we test this : Output TDS from 1,500 ppm input | 120 ppm |
| Reject water at 450 ppm input How we test this : Reject water at 450 ppm input | 2.4 L per L |
| Reject water at 900 ppm input How we test this : Reject water at 900 ppm input | 3.1 L per L |
| Time to fill a 20 L can How we test this : Time to fill a 20 L can | 45 min |
| Pump noise at 1 m How we test this : Pump noise at 1 m | 44 dB |
Measured on the unit we tested.
How we tested
We tested the Z2 Pro on a borewell supply that read 450 to 900 ppm TDS, with a 1,500 ppm spike. We logged output TDS with a handheld meter, timed 20 L fills, collected reject water in a jug, recorded noise at 1 m and watched the display for filter-change alerts.
We bought this unit at retail price.
How does the AO Smith Z2 Pro Under the Counter RO Water Purifier compare?
-
Boon Tap Under Sink RO Water Purifier A 9.1
The Boon Tap RO beats the Z2 Pro on warranty (2 years vs 1), tap clearance (35 cm vs 24 cm), app support and water wastage. Its filter set also costs about half as much as AO Smith's.
Key specs
| Type | 100% RO with copper-fortified mineraliser, 7 stages (AO Smith) |
|---|---|
| Storage | 6 L approx. (AO Smith) |
| Input TDS | Up to 2,000 ppm, side-stream RO membrane (AO Smith) |
| TDS reduction | 95 percent or more (AO Smith) |
| Power | 48 W max, 150 to 300 V AC (AO Smith) |
| Pressure range | 7 to 30 psi (AO Smith) |
| Size and weight | 42 x 41 x 27 cm, about 11 kg (AO Smith) |
| Faucet | Gooseneck faucet, installation free, countertop drilling not included (AO Smith) |
| Warranty | 1 year comprehensive (AO Smith) |
Questions buyers ask
How much do AO Smith Z2 Pro filter replacements cost?
AO Smith does not publish a genuine kit price. In our experience a full set (RO membrane, carbon and sediment) costs about Rs 7,500, close to double the Rs 4,000 for Boon's set. Third-party estimates are lower, so get a written quote from AO Smith customer care before you buy.
What TDS can the AO Smith Z2 Pro handle?
AO Smith rates the Z2 Pro for borewell, tanker and mixed supplies up to 2,000 ppm TDS. On our 900 ppm borewell water it delivered about 55 ppm, and about 120 ppm from a 1,500 ppm spike.
How much water does the AO Smith Z2 Pro waste?
AO Smith's page gives recovery as up to 30 percent in the specs and 55 percent under features, and does not reconcile them. We measured about 2.4 L of reject per litre of purified water at 450 ppm.
Does the AO Smith Z2 Pro fit under a modular kitchen sink?
Usually, but at 42 x 41 x 27 cm and 11 kg it is bulkier than slimmer rivals. Check cabinet depth, and note that countertop drilling for the faucet is not included in free installation.
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