What water tests you actually need before buying a plant
Short answer: Before specifying any treatment, you need at minimum TDS, hardness, pH, iron, turbidity and chlorine. Without these figures, any plant specification is guesswork — and a plant designed for the wrong water either fails or costs far more to run than it should.
Several of these you can test yourself with inexpensive kits.
The essential six
| Parameter | Why it matters | Test |
|---|---|---|
| TDS | Decides RO or not | TDS meter, ₹2,730 |
| Hardness | Decides softener size and antiscalant | Hardness kit, ₹1,050 |
| pH | Affects treatment chemistry | pH indicator, ₹7,035 |
| Iron | Fouls resin and membranes | Laboratory |
| Turbidity / SDI | Decides pre-filtration | SDI kit, ₹5,565 |
| Chlorine | Damages RO membranes | DPD test kit |
What each result means
TDS
| TDS (ppm) | Implication |
|---|---|
| Below 200 | RO may not be needed |
| 200 – 500 | Acceptable for most uses |
| 500 – 2,000 | RO recommended |
| Above 2,000 | RO needed, recovery limited |
Hardness
| Hardness (ppm) | Implication |
|---|---|
| Below 150 | Softening usually not needed |
| 150 – 300 | Softening recommended |
| Above 300 | Softening needed, especially for boiler |
See our hard water effects guide.
Iron
SDI
- Below 3 — good for RO
- 3 to 5 — improve pre-treatment
- Above 5 — membranes will foul quickly
SDI is more relevant to RO than turbidity, because it detects very fine particles a turbidity meter misses. See our turbidity and SDI guide.
Additional tests for specific situations
| Situation | Also test |
|---|---|
| Boiler feed | Alkalinity, silica, conductivity |
| Drinking water | Bacteria, nitrate, fluoride, arsenic |
| High recovery RO | Sulphate, silica, barium |
| Surface water source | Organic matter, colour, bacteria |
| Coastal area | Chloride, sodium |
| Industrial area | Heavy metals |
What you can test yourself
- TDS — a meter, daily use
- Hardness — a titration kit, five minutes
- pH — a meter or paper strips
- Chlorine — DPD tablets, one minute
- SDI — a kit, takes about fifteen minutes
These are the ones you need regularly, so owning the kits pays for itself quickly.
What needs a laboratory
- Iron, manganese and heavy metals
- Silica, sulphate, barium
- Nitrate, fluoride, arsenic
- Bacteria and coliform
- BOD and COD for effluent
- Full ionic analysis for RO design
Sampling correctly
A bad sample gives a bad result regardless of how good the laboratory is:
- Let the water run for a few minutes before sampling — do not take stagnant pipe water
- Use a clean container, rinsed with the same water
- Fill completely, leaving no air gap where testing dissolved gases
- Label with date, time and sampling point
- Deliver to the laboratory quickly — some parameters change within hours
- For bacteria, use a sterile container from the laboratory
Test at different times
Water quality changes. Borewell TDS often rises through summer as the water table drops, and surface water turbidity rises sharply in monsoon.
So design for the worst case, not the day you happened to sample. If possible, test in both summer and monsoon before finalising a design.
Routine testing once running
| Test | Frequency |
|---|---|
| Feed and permeate TDS | Daily |
| Hardness after softener | Daily |
| Chlorine before membrane | Daily |
| pH | Daily |
| SDI | Monthly |
| Full analysis | Annually, or when the source changes |
See our test kits range.
Get your water tested
Send us your water analysis and what you need the water for, and we will recommend the right treatment.
💬 WhatsApp par poochhein 📞 9910646957Frequently asked questions
Which water tests are needed before buying a treatment plant?
At minimum TDS, hardness, pH, iron, turbidity or SDI, and chlorine. Without these figures any plant specification is guesswork, and a plant designed for the wrong water either fails or costs far more to run.
Which tests can I do myself?
TDS with a meter, hardness with a titration kit, pH with a meter or strips, chlorine with DPD tablets, and SDI with a kit. These are the ones needed regularly, so owning the kits pays for itself quickly.
Why does iron matter so much?
Above zero point three ppm it fouls both softener resin and RO membranes, and the fouling is difficult to reverse. Iron removal must come before the softener in the treatment train, not after.
How should a water sample be taken?
Let the water run for a few minutes first rather than taking stagnant pipe water, use a clean container rinsed with the same water, label it with date and sampling point, and deliver it to the laboratory quickly.
Should I test at different times of year?
Yes if possible. Borewell TDS often rises through summer as the water table drops, and surface water turbidity rises sharply in monsoon. Design for the worst case rather than the day you happened to sample.