The motor clicked at 5:30am and the gali was still dark. I filled a steel glass from the RO tap the way I do every May in Jaipur, when tanker smell sits in the lane. The cheap TDS meter next to the masala box jumped from yesterday’s 90 to 410. The water still looked clear. Nobody had changed a filter. A jump like that feels like a trick, and the filter boy will sell you a full kit before breakfast. Wait. Test twice. The source may have changed, a membrane may have clogged, or reject water may be mixing back into the product line.
Home checks before you buy a full kit
Rinse the TDS meter twice. Cheap meters lie if the probe is wet with yesterday’s sample or if you dip it into a steel tumbler that still has salt from dal. Use a clean plastic glass. Note three numbers, not one: tank water before the RO, product water after the RO, and the reject line if you can reach it. Open the tank lid with a torch. If tank water itself jumped from 400 to 1200 because the jal board mixed a high-TDS source overnight, the RO did not fail. A 90 to 410 jump on the RO tap can still mean the membrane is tired, but it can also mean the inlet is now 1800 instead of 600.
Flush the RO for two minutes. Stale water in the post-carbon overnight reads higher. If the number falls after a flush, you do not need a kit at dawn. If it stays high, shut the inlet and look at the waste pipe. A pinched waste pipe, a clogged flow restrictor, or a tee someone fitted “to save water” can push reject back toward the product tank. Taste is a poor test. A plastic or sweet chemical smell is a better clue that a membrane is rupturing.
Check the last service sticker. Pre-filters clog first in Rajasthan dust. A yellow sediment candle after a tanker week is normal. A membrane that is two years old in a 1500 TDS colony is also a fair suspect. Do not throw every cartridge on the same day unless all three numbers tell you the same story.
Photos that prove the TDS jump
Photograph the meter in the glass with the reading visible, and the phone clock if you can. One isolated number on WhatsApp is how shops start an argument. Take the tank water reading and the RO tap reading on the same morning. Shoot the service sticker, the model sticker, and the waste pipe while water is running. If reject is a thin thread and product is a fat stream, the membrane may be bypassing. If both are fat, someone may have removed the restrictor.
Photograph the overhead tank if it looks cloudy after a tanker. Tanker water in summer can sit at a different TDS from the board line. Neighbours who filled from the same tanker should show similar readings. If your tank is 1400 and theirs is 500, your tank is mixing something else — a rainwater downpipe, a leftover reject drum, or a sump pipe that was never isolated.
Keep the photos for seven days. TDS can bounce when the board switches a tubewell. One night is not a career for a membrane.
Neighbour timing and the same source water
Ask who filled at 5:15am and who filled at 6:40am. The first hour in many Jaipur and Jhunjhunu lanes is board water. The second hour is often a booster or a tanker topping the line. If the neighbour’s RO still reads 80 and yours reads 400, your machine or your tank is the problem, not the ward. If every RO on the floor jumped, the source changed. That is the cheapest diagnosis in the building.
Shared terraces lie. One house ties RO reject into a common drain that backs up into another overflow. One helper pours reject into the wrong drum. Ask when they last changed their sediment filter. If three families changed last month and you did not, you are late, not cheated.
In a village cluster near a late monsoon, handpump water and tanker water swap through the week. A meter that jumped after a tanker day is not a filter crime. Test again on a board-only morning.
Complaint and service path
Call the shop that last stamped the service card, not a random lamp-post number. Ask for a TDS check at inlet and outlet, written on paper, with the technician’s name. If they only want to sell a kit, wait for the numbers. A board complaint is useless for a private RO unless the inlet is sewage-tinged.
If you suspect mixing of reject and product, a plumber who understands RO tees is more useful than a filter salesman. Shut the system, open the cabinet, and ask them to show the product line versus the waste line. Do not let anyone dump old cartridges in your bin before you photograph the old ones. Brown sludge on a pre-filter is dust. A torn membrane wrapper with no date is a story.
If the water smells of sewage, stop drinking. That is not a TDS-kit morning. That is a tank lid, a cross-connection, or a drain. File with the ward only if the public line is the source. For a household RO, the path is shop, then plumber, then a water test from a local lab if you still do not trust the glass.
Approximate INR rates that vary by ward
These figures move with the gali and the season. A sediment candle in a small Jaipur shop may be ₹250 to ₹600. Carbon can sit between ₹400 and ₹900. A domestic membrane is often ₹1,500 to ₹4,500 depending on brand. A service visit without parts is commonly ₹200 to ₹500. A handheld TDS meter is ₹150 to ₹400.
A plumber who traces a reject-product mix might ask ₹300 to ₹800 for a short visit. A basic lab TDS slip in a district town can be ₹150 to ₹400. Tanker water is a separate bill. Confirm every number in your ward. A colony next to a high-TDS tubewell pays more often than one on a softer line.
Refuse a “full kit, cash, no bill” demand at 7am. Ask for a written list of parts. If the inlet TDS is the thing that jumped, a kit will not save you for more than a week.
FAQ
Should I change the membrane the same morning the number jumps?
No. Flush, test tank water and product water, and test again after the next supply hour. If inlet TDS rose with the board or a tanker, the membrane may still be working. Change when product stays high after a flush and the inlet is not the whole story.
Can a clogged pre-filter alone send TDS from 90 to 400?
Usually not by itself. A clogged pre-filter cuts flow and can stress the membrane, but a four-times jump overnight often means source change, a damaged membrane, or mixing. Replace a visibly filthy candle, then retest before you buy everything else.
Is reject water safe to put back into the drinking tank to save water?
No. Reject is the concentrated leftover. Tying it into the same tank that feeds the RO will raise TDS, muddy taste, and waste the motor hour. Use reject for mopping or plants only if your plumber isolated that drum.
How often should a Rajasthan home change RO parts in summer?
There is no single calendar. Dust, tanker weeks, and inlet TDS decide. Many homes change sediment more than once in a hard summer and keep the membrane until product TDS climbs and stays. Follow the readings and the service slip, not a poster.
Short note
Paani Atka is not a jal board and not a filter shop. The official ward office is final on public supply quality. Private RO work is a household contract. Boring, if you ever need it, needs a local permit. Rates above are approximate and they change by ward. Confirm on the ground before you pay.