Alkaline Water Purifier Buying Guide: What It Does and What to Check

An alkaline water purifier cleans the water first, usually with RO, and then passes it through a cartridge that adds minerals such as calcium and magnesium. Those minerals buffer the water, nudge its pH upward and change how it tastes. It does not change the pH of your blood and it does not cure disease: what you are really buying is better-tasting, mineral-bearing water from a machine that must still do the hard work of purification first.

This is a buyer’s guide. If you want the science of copper against alkaline, read our copper vs alkaline water purifier explainer, and for a three-way view see alkaline vs copper vs mineral purifiers compared. Here we focus on what the stage does, which claims to ignore and what to check before you pay.

What an alkaline purifier actually does

Most alkaline purifiers sold for Indian homes are an RO purifier with an extra stage at the end. The RO membrane removes most dissolved solids, including the calcium and magnesium bicarbonates that give natural water its buffering. The water that comes out is low in TDS and often slightly acidic or close to neutral, because there is little left in it to resist carbon dioxide dissolving from the air. If you want the detail, our guide on whether RO removes minerals from water covers it.

The alkaline stage then runs this low-TDS water over a bed of mineral media. As the water flows through, small amounts of minerals dissolve into it: typically calcium and magnesium compounds that act as a pH buffer. The result is water with a little more dissolved mineral content, a pH nudged upward, and a rounder taste.

“Alkaline water machines” that use electrolysis are a different category: they do not purify, so the water you feed them must already be safe.

Your body and pH: what changes and what does not

A lot of alkaline marketing rests on the idea that drinking alkaline water makes your body less acidic. Physiology does not work that way.

• Your stomach is strongly acidic by design. It needs that acid to digest food. A glass of mildly alkaline water meets that acid almost immediately and is neutralised.
• Blood pH is held in a very narrow range by your lungs and kidneys, all day, whatever you eat or drink. If blood pH ever moves out of that range, it is a sign of serious illness that needs a hospital, not a change of drinking water.

Two practical health notes. If you have kidney disease or have been told to watch your calcium, magnesium or overall mineral intake, ask your doctor before you switch to mineral-added water. And if you have persistent acidity, reflux or stomach pain, see a doctor: a water purifier is not a treatment for any of these.

Real benefits vs marketing claims

Strip away the claims that are not supported and alkaline water still has honest reasons to exist. This is how the common claims hold up.

Claim	Does it hold up?
Tastes better than plain RO water	Often, yes. Minerals give water body and take away the flat taste many people notice in low-TDS RO water. Taste is personal, so try it.
Adds calcium and magnesium	Yes, in small amounts. Your diet remains the main source of both; the water is a minor top-up.
“Neutralises acidity in the body”	No. See the section above on stomach acid and blood pH.
Prevents or cures cancer, diabetes, arthritis or other disease	No reliable evidence. Treat any such claim as a red flag about the seller.
Hydrates better than ordinary water	No reliable evidence. Clean water hydrates; the pH is not the deciding factor.

What pH range is sensible

The Indian drinking water standard, BIS IS 10500, sets an acceptable pH range of 6.5 to 8.5. That is a sensible target for any purifier, alkaline or not. A good alkaline stage lifts low-TDS RO water into the comfortable middle or upper part of that range; it does not need to push beyond it.

Higher is not better. Water well above 8.5 can taste bitter or slightly soapy, and a very high number on a brochure is a marketing choice, not a benefit.

Three things to keep in mind when you test:

• Output pH depends on your input water and on cartridge age. Mineral media dissolves as it works, so the effect is strongest when the cartridge is new and fades over its life.
• Strips and drops are fine for a rough check. Digital pH meters need calibration to be accurate.
• TDS will rise slightly after the alkaline stage. That is expected: you are adding dissolved minerals. A small rise after a mineral stage is not a fault in the RO.

What to check before you buy

1. Does it purify first? The alkaline or mineral stage must come after full purification. A mineral cartridge adds; it does not remove contaminants, bacteria or excess TDS.
2. Is the RO rated for your input TDS? Find out what comes out of your tap before you compare models. Different membranes are rated for different input levels.
3. Is the alkaline stage separate and replaceable? Ask whether you can buy and change the mineral cartridge on its own, and what it costs.
4. Can you choose when to use it? Some people want mineral water for drinking but plain water for cooking or for babies. Check whether the unit lets you choose.
5. What exactly does it add? Ask which minerals the cartridge releases. “Alkaline” alone is a description of pH, not of what is in the water.
6. How will you know it is exhausted? Ask whether the purifier tells you, or whether you are expected to change it on a guess.
7. Read the claims, and ask who services it. Disease-cure language is a reason to look elsewhere; a clear answer on who changes cartridges is a reason to stay.

Why separate cartridges matter

Some alkaline purifiers combine the mineral media with a filter stage in one cartridge. That keeps the parts count low, but it ties two jobs together that wear out at different rates. Keeping the mineral stage on its own cartridge has practical advantages:

• Purification is never disturbed. Changing or switching the mineral stage does not open the path that cleans the water.
• You replace only what is used up. Mineral media is consumed as it dissolves; filters clog at their own pace. Separate parts mean you are not paying to replace one because the other is spent.
• You can change your mind. If you want a different taste later, you change one cartridge, not the purifier.

Where Boon Homie fits, and where it does not

Boon is a water-technology company founded in 2013 by ex-IIT Kanpur engineers, backed by the Technology Development Board (Govt. of India), NITI Aayog and Roca, with systems running in more than 4,000 organisations. Boon Homie, our wall-mounted RO purifier, takes the separate-cartridge approach described above.

Purification comes first, through five stages: InletShield (5-micron grooved pre-filter), ProFlow (5-micron sediment and turbidity control), CarbonCorrect (chlorine and chemical taste), CoreRO (an RO membrane rated for input up to 2000 TDS) and UV ProGlow (in-line LED UV before the tank). It purifies at 20 litres per hour into an 8-litre tank.

After that, Homie offers three Mineral Enhancers, each on its own cartridge separate from the main filter, so switching never touches purification:

• Balance: smoother, fresher water with a gentle lift in pH.
• Uplift: pH-buffering minerals for a more alkaline profile.
• Reboot: restores calcium and magnesium, for taste, mouthfeel and stability.

On the front are three Water Profile buttons: Active (for after exercise and mornings), Daily (balanced, for everyday drinking and cooking) and Bev (for brewing coffee and tea). One press, no app needed. WaterAI monitoring shows input TDS, output TDS, temperature and filter health. Homie is ₹21,900 at the time of writing, on pre-order with deliveries from 15 October 2026, with free installation by Boon’s own team and a 2-year warranty.

Where it does not fit: if your supply is above 2000 TDS, Homie’s membrane is not rated for it. If you want an electrolysis machine that promises a specific high pH number, Homie is not that, and we would argue you do not need one. If you would rather hide the purifier in the cabinet under the sink, a wall-mounted unit is the wrong format.

Frequently Asked Questions

Is alkaline water good for health?

Alkaline water is safe to drink when it stays within the BIS IS 10500 pH range of 6.5 to 8.5, and many people prefer its taste. There is no reliable evidence that it prevents or cures disease or changes your blood pH, which your lungs and kidneys keep in a narrow range. If you have kidney disease or a mineral restriction, ask your doctor before switching.

What pH should an alkaline water purifier give?

A sensible target is within the BIS IS 10500 acceptable range of 6.5 to 8.5, usually in its middle or upper part. Higher is not better: water well above 8.5 can taste bitter or soapy. Output pH also depends on your input water and on how old the mineral cartridge is, so expect it to vary a little over time.

Does an alkaline cartridge purify water?

No. An alkaline or mineral cartridge adds minerals to water that has already been purified. It does not remove bacteria, excess TDS, chemicals or heavy metals. That is why the alkaline stage should always sit after the full purification stages, such as sediment filters, carbon, RO and UV, and never replace them.

Why does RO water become slightly acidic?

RO removes most dissolved minerals, including the bicarbonates that buffer natural water. With little left to resist it, carbon dioxide from the air dissolves into the water and forms a weak acid, so the pH drifts down. It is not harmful, but it can make the water taste flat. A mineral or alkaline stage adds buffering minerals back.

Is an alkaline water machine the same as an alkaline purifier?

Not usually. An alkaline purifier is an RO or similar purifier with a mineral stage added after purification. An alkaline water machine typically uses electrolysis to split water into alkaline and acidic streams. It does not purify on its own, so the water you feed it must already be safe. For most Indian homes, purification is the first decision.