Buying guide

TDS, EC and pH meters: what each measures and which you need

Reviewed 8 September 2026

Before the detail, the short version. TDS answers "how much is dissolved in this water?". EC answers the same question from the other side, by measuring how well the water carries electricity, which rises with dissolved salts. pH answers a completely different question: "is this liquid acidic or alkaline?". A meter that reads dissolved content tells you nothing about acidity, and a pH meter tells you nothing about dissolved content. That is why the choice starts with knowing which question you are actually asking.

TDS stands for total dissolved solids, the total amount of minerals, salts and other matter dissolved in the water. A TDS meter reports it in parts per million, or ppm, where one ppm is one milligram of dissolved solids in one litre of water. A low ppm means purer water, a high ppm means more is dissolved in it. This is the reading home users and filtration shops care about most, because it is the simple way to judge whether drinking water is clean and whether an RO (reverse osmosis) filter is doing its job. As a rough guide only, RO systems are often expected to bring water well down into the low tens of ppm, and a rising reading over time tells you the membrane is tiring. Confirm the target for your own system with its maker rather than treating any single number as a pass mark.

A pocket TDS meter is the value entry point to water testing. You dip it into a glass or sample and read the ppm in a second. Our TDS-3 pocket meter is the plain single-reading model for exactly this: home RO checks, water suppliers, and shops that fit filtration.

EC stands for electrical conductivity, a measure of how well the water carries an electric current. It is usually reported in microsiemens per centimetre. Pure water is a poor conductor; the dissolved salts are what carry the current, so the more salt is dissolved, the higher the conductivity. That is the key point: EC and TDS are measuring the same underlying thing, the dissolved content, from two angles. In fact a TDS meter does not weigh anything, it measures conductivity and then converts it to a ppm figure using a fixed conversion factor. This is why the two readings track each other.

So who wants EC directly rather than TDS in ppm? Growers above all. In hydroponics (growing plants in a nutrient solution instead of soil) the nutrient strength is managed by conductivity, so EC is the number on the recipe. Aquarium keepers and water-treatment operators also watch conductivity. A combined meter gives you both readings so you do not carry two units. Our TDS and EC combined meter and the pocket TDS and conductivity meter both report ppm and conductivity together, which suits anyone who wants the fuller picture a plain TDS pen does not give.

pH is the odd one out, and the one people most often confuse with the others. It measures how acidic or alkaline a liquid is, on a scale from 0 to 14. Below 7 is acidic, exactly 7 is neutral (pure water), above 7 is alkaline. It has nothing to do with how much is dissolved: two samples can have the identical TDS and completely different pH. If your question is about acidity, and it will be for drinking water suppliers, pools, hydroponics, food and drink checks, and school and college labs, then you need a pH meter, and a TDS or EC meter will not answer it.

One practical thing sets pH meters apart: they must be calibrated with buffer solution to stay accurate, and the electrode needs to be kept wet and clean. A TDS or EC meter needs far less fuss. So budget for buffer sachets when you buy a pH meter. Our pocket pH meter is the affordable way into pH testing, and the bench-top pH meter from Bante suits a lab that tests through the day rather than the occasional check. Ask us about buffer solution when you order either.

Because they measure the same thing, the choice is about which units your work uses, not which is more accurate.

• Checking drinking water or an RO filter? Buy a plain TDS meter in ppm. That is the number everyone in filtration talks in.
• Running hydroponics or dosing nutrients? Buy a meter that shows EC (conductivity), because nutrient recipes are written in EC.
• Want both, or not sure yet? A combined TDS and EC meter covers both units on one unit and costs a little more than a plain TDS pen.
• Remember neither of these reads acidity. If you also need pH, that is a separate meter.

• Home RO or drinking water: a pocket TDS meter to check purity and watch the filter over time.
• Water supplier or filtration shop: a TDS meter for quick customer demonstrations; add a pH meter if customers ask about acidity.
• Hydroponics and growers: an EC or combined meter for nutrient strength, plus a pH meter, because both matter to plants.
• Aquarium: a combined TDS and EC meter to track dissolved content, and a pH meter for tank chemistry.
• Swimming pool: a pH meter for water balance is the priority.
• College, school or QC lab: a bench pH meter for regular work, and TDS or EC meters as the syllabus or tests require. See our companion guide on setting up a college or QC laboratory.

A meter only earns its keep if the reading is true. A few habits keep it that way. Calibrate a pH meter regularly with buffer solution, commonly at pH 4, 7 and 10, and store the electrode wet, never dry, because a dried-out electrode drifts or dies. Rinse the probe with clean or distilled water between samples so the last sample does not skew the next. For TDS and EC meters, be aware that the ppm figure depends on the conversion factor the meter uses, so two TDS pens can read slightly differently on the same water; what matters is that you use one meter consistently and watch the trend. Temperature affects conductivity too, which is why many meters have automatic temperature compensation, worth having if your samples vary in temperature.

The meters linked here are stocked at our Lahore shop, brand new box pack, and you can see the range on the water and liquid testing page. The pocket TDS, combined TDS and EC, and pocket pH meters are carried at published prices; the Bante bench pH meter we quote on request. We also stock buffer solution for pH calibration, so ask when you order. If you need something we do not carry, a portable dissolved oxygen meter, a higher-grade bench conductivity meter, or a specific pH model, message us on WhatsApp. We can often source it, and if we cannot, we will tell you honestly which meter we stock comes closest.