💧 Water purifier FAQ
Water Purifier FAQ: Straight Answers, No Sales Pitch
These are the questions we are asked most often, answered as briefly as they can honestly be answered. Where a question deserves more than three sentences, the link under each answer goes to the page that treats it properly.
One thing worth saying up front, because it shapes every answer below: the most common expensive mistake in this category is not buying the wrong brand. It is buying purification you do not need — fitting a ₹20,000 RO purifier to 150 ppm municipal supply, where it strips minerals, discards two litres for every litre you drink, and costs roughly ₹17,000 more over five years than the correct answer.
Choosing a technology
The decisions that come before you look at a single model.
Which water purifier is best for my home?
The one that matches your water, not the one at the top of a list. Measure your TDS with a ₹300 meter: under 200 ppm on treated municipal supply, UV+UF is correct and cheaper; over 300 ppm or any borewell or tanker source, you need RO with UV and a TDS controller. Only after that does the choice of model matter.
What is the difference between RO, UV and UF?
RO removes what is dissolved in water — salts, heavy metals, arsenic, fluoride. UV kills what is alive in it. UF physically filters out what is floating in it. They solve three different problems, which is why the right answer depends on which problem your supply actually has.
Do I need RO if my water is municipal supply?
Usually not, if it measures under about 200 ppm and there is no known contamination in your district. Fitting RO to soft treated water strips minerals, wastes two litres for every litre you drink, and costs roughly ₹17,000 more over five years than UV+UF to solve a problem the treatment plant already solved.
Is an alkaline or copper purifier worth the extra money?
Both are post-treatment cartridges on an ordinary RO purifier, not different purification technologies. Alkaline addresses the flat taste of RO water by adding calcium and magnesium back, which is defensible on high-TDS input. Copper is a taste and tradition purchase. Neither has evidence supporting broader health claims.
How many stages does a water purifier need?
Functionally four to six. Ignore headline counts of 10 or 12 — Indian marketing counts sediment pads, carbon polishers and mineral cartridges as separate stages. Confirm which technologies are physically present: an RO membrane with a stated TDS rating, a UV lamp, a UF membrane if you are paying for one, and a working TDS controller.
TDS and water quality
What is a safe TDS level for drinking water?
BIS IS 10500 sets 500 ppm as the acceptable limit and 2,000 ppm as the permissible maximum where no alternative source exists. For taste and mineral content, most people prefer 50-150 ppm. Below about 30 ppm the water tastes flat and lacks useful calcium and magnesium — near-zero TDS is not a goal.
How do I check my water's TDS at home?
Buy a digital TDS meter for about ₹300. Run the tap for 30 seconds, collect water in a clean glass at room temperature, immerse the probe to the marked line, and wait 10-20 seconds for the reading to settle. Measure the raw supply, and measure twice — once in summer, once in monsoon.
Can a TDS meter detect contamination?
No, and this is its most important limitation. It measures total dissolved content, not composition. Arsenic, fluoride, nitrate, lead and bacteria can all be present at a perfectly normal TDS reading. For those you need a NABL-accredited lab test at ₹800-2,500.
What is hard water and does RO fix it?
Hardness is dissolved calcium and magnesium, and it causes scale, soap scum and stiff laundry rather than health harm. RO removes it from the one tap it is plumbed into. For scale in geysers, washing machines and bathrooms you need a softener at the inlet — a purifier at the sink will not help.
Is RO water safe to drink every day?
Yes. The mineral-loss argument is real but small — diet contributes far more calcium and magnesium than water does. The practical fix is a TDS controller set to leave the output at 60-100 ppm, which restores taste and some mineral content at no recurring cost.
Running costs and maintenance
How much does a water purifier cost to run per year?
A gravity purifier costs ₹600-1,200 a year, a UV+UF unit ₹1,500-3,500, and a domestic RO ₹4,000-7,500 once you include pre-filters, the membrane, the UV lamp and service visits. Electricity is a small fraction of that — filters and service are the real cost.
How often should RO filters be changed?
Pre-filters every 6-9 months, the UV lamp every 12 months whether or not it has failed, and the RO membrane every 18-30 months. The clearest signal for the membrane is output TDS: record it at installation and every few months afterwards, and replace when it has climbed substantially.
How much water does an RO purifier waste?
Typically 2-3 litres per litre purified, or closer to 1 litre on a good unit with a working booster pump. For a family of four that is roughly 7,300 to 22,000 litres a year. Low inlet pressure is the biggest fixable cause of a poor ratio.
Is a water purifier AMC worth it?
Usually from year three onward, less so in year one when the unit is still under warranty. The value is less in the parts than in someone attending on schedule — the most common cause of premature membrane failure is a pre-carbon cartridge nobody replaced. Insist that input and output TDS are recorded on every visit.
Why has my purifier's output TDS gone up?
Almost always a failing RO membrane, and usually because chlorine reached it through an overdue pre-carbon cartridge. A membrane fails silently — no noise, no leak, no indicator — so a rising output reading is the only warning you get. Replace it rather than waiting for the service schedule.
Installation and practicalities
Where should a water purifier be installed?
On a solid masonry wall near the sink at 1.2-1.5 m height, within reach of a cold-water tee, a drain point for the reject line and a dedicated socket. Leave 15 cm of clearance around the front panel for filter changes, and keep it away from the hob.
Under-sink or wall-mounted — which should I choose?
Wall-mounted for most homes: cheaper to install, easier to service, larger tank, and removable if you move. Under-sink if you own the property, have reliable supply and want nothing on the counter — accept the higher installation cost and harder service access.
Can I install a water purifier in a rented flat?
Yes. Counter-top and gravity models need no fixing at all. Wall-mounted units need four anchor holes, which most landlords accept — confirm first. Avoid under-sink installation in a rental, since it requires drilling the countertop and that cannot be undone.
What capacity purifier does a family of four need?
A family of four uses roughly 15-20 litres a day for drinking and cooking, so a 7-8 litre storage tank refilling through the day is comfortable. Buy a larger tank only if your supply arrives in a short daily window or power cuts are routine.
Question not answered here?
Tell us your city and your situation and we will give you a straight answer — including when the honest answer is that you do not need to spend much at all.