What Is TDS in Water?
TDS (Total Dissolved Solids) measures the total concentration of all dissolved substances in water — primarily minerals including calcium, magnesium, sodium, potassium, bicarbonates, chlorides and sulphates. It is expressed in milligrams per litre (mg/L) or parts per million (ppm) — numerically equivalent.
TDS does not tell you what specific dissolved substances are in your water, only the total amount. Water with 800 ppm TDS could be primarily harmless calcium and magnesium (common in Lahore bore water) or could include arsenic, nitrates or other contaminants. This is why a full water test is needed for system design — a TDS reading is a useful starting point, not a complete answer.
TDS Scale — What the Numbers Mean for Pakistan
| TDS Range (ppm) | Classification | Pakistan/WHO Status | Treatment Needed | Lahore Context |
|---|---|---|---|---|
| 0–150 | Very low (near distilled) | Below all limits | None or mineralisation | Typical RO output range |
| 150–300 | Low TDS | Below WHO guideline (600) | Usually none | WASA supply in some areas |
| 300–600 | Moderate | WHO: acceptable; Pakistan: within limit (1000) | Possible RO if other params elevated | WASA variable; some areas |
| 600–1000 | High | Above WHO; within Pakistan limit | RO recommended | Lower range Lahore bore water |
| 1000–2000 | Very high | Above Pakistan limit (1000 ppm) | RO required | Typical Lahore residential bore water |
| Above 2000 | Extremely high | Far above all limits | RO required; specialist design | Some deep bore wells; Ichhra, Rehmanpura |
Can High TDS Make You Sick?
TDS itself — primarily calcium and magnesium in Lahore bore water — is not acutely toxic at typical elevated levels. However, very high TDS water is associated with: poor palatability (bitter/salty taste), scaling in pipes and appliances, and potential cardiovascular effects from very high mineral intake over long periods.
More critically in Lahore, high TDS bore water is typically accompanied by: high hardness (appliance and pipe scaling), microbiological contamination (direct health risk), and potentially elevated arsenic or nitrates depending on local geology. These associated parameters, not TDS itself, represent the most significant health concerns in Lahore bore water.
What TDS Should Your RO Output Be?
A well-maintained RO system on typical Lahore bore water (800–1500 ppm input) should produce permeate at 30–150 ppm TDS — 90–98% rejection. Record your baseline TDS at installation. If permeate TDS has risen to 200 ppm+ from a 50 ppm baseline, membrane performance is declining and the system needs assessment.
TDS Meter vs Full Laboratory Test — Which Do You Need?
A TDS meter (PKR 500–2,000) is excellent for monthly monitoring of your RO output after installation. It gives you an instant reading and allows you to track membrane performance over time.
A full laboratory water test is required before RO system design. It identifies hardness, iron, arsenic, microbiological contamination and pH — none of which a TDS meter can detect. Use the lab test for design; use the TDS meter for ongoing monitoring.
Frequently Asked Questions
What is TDS in water?
TDS (Total Dissolved Solids) is the total concentration of all dissolved minerals in water, measured in ppm or mg/L. It includes calcium, magnesium, sodium, chlorides, sulphates and other dissolved substances. It does not indicate which specific substances are present, only the total amount.
What TDS level is safe to drink in Pakistan?
Pakistan drinking water standard allows up to 1000 mg/L TDS. WHO recommends below 600 mg/L. Below 300 ppm is considered good quality. Most Lahore bore water is 700–2000 ppm without treatment — above both benchmarks.
Does RO remove TDS?
Yes. RO membranes reject 95–99% of dissolved solids, reducing TDS from 800–1500 ppm (typical Lahore bore water) to 30–150 ppm in the permeate. This is the primary reason RO is the appropriate technology for Lahore bore water purification.
How do I check TDS at home?
Use a TDS meter (PKR 500–2,000). Submerge the probes in water; the display shows TDS in ppm. Check your tap water before treatment and your RO output monthly, recording results for trend monitoring.
Test Your Water TDS With Aqua Prima
We test TDS, hardness, iron, pH and microbiological parameters — the full picture. Free consultation from Ichhra, Lahore.
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