TDS Water Meters: Water Quality Test

Updated: June 22, 2024.

You bought and installed a water filter, and you are probably enjoying the purest and safest water. That’s what you think. But how exactly can you make sure that your water filtering is working properly? Well you may notice some physical changes in the quality of water, such as clearness, odor, taste. Or you can pay for expensive water tests at private laboratories. Once you have a water filter, you are probably looking for a do-it-yourself way of testing your water.

Pure Water and TDS Measuring

Total Dissolved Solids- Indicator Of Water Quality

You may think that if the filtered water looks clear, smells and tastes great it is pure. However, your filtered water can still be loaded with a high level of unfiltered water contaminants. It is impossible to notice these undetected contaminants because they are odorless, invisible, and tasteless. Therefore, you will need a device capable of detecting water contaminants that are elusive to human senses. This device is known as a TDS (Total Dissolved Solids) Meter. A TDS meter basically checks if a water filter is working properly.

TDS Water Quality testing

Total Dissolved Solids (TDS) is the combined amount of all organic and inorganic substances in water. TDS is anything with a chemical structure other than pure water, or H20. Total Dissolved Solids includes salts, minerals, metals, and just about anything else that is dissolved in water. Since these chemicals are dissolved in water, they cannot be detected by a human. Pure water does not conduct electricity, while certain dissolved chemicals do. Therefore, TDS tests are based on the principle of electrical conductivity.

Pocket TDS Testers

TDS is measured in units of mg/L, or more frequently, parts per million (ppm.) The maximum level of TDS in water as set by the EPA (Environmental Protection Agency) is 500 mg/L or 500 parts per million (ppm.). Water above 500 ppm is considered unsafe to drink , unless you are in California where TDS can be commonly even above 1000. Water below 30 ppm is also unsafe to drink , it is considered to be Industrial Water used for commercial / industrial applications such as manufacturing of pharmaceuticals and household products and electronics. Water does not exist in nature at very low to 0 TDS , this is a common misconception and a way for some shady companies to sell you their incorrectly built Reverse Osmosis systems.

TDS Scale

TDS Level Explained

A TDS water meter measures TOTAL DISSOLVED SOLIDS, including good and bad solids. One of the major components of TDS is calcium, which is beneficial mineral. Because it is naturally found everywhere, it's common when 50%-90% of TDS measurement is calcium. So what is a TDS for anyway then? It is an indicator of the efficiency of a Reverse Osmosis System (RO) and of performance of its membrane. A high level of TDS indicates that the RO system is not filtering out enough. A low level of TDS implies that the RO membrane is doing its job well. Be vary of RO systems and non-RO systems that show TDS close to 0, it is not for drinking water.

A TDS water meter is small, compact, affordable, maintenance free, and durable. So let’s take a look at some great TDS water meter products, and have you on the way to testing the performance of your water filter.

TDS Handheld Meter

The TDS-3 Hand Held Meter With Carrying Case from HM Digital is an excellent choice. This TDS meter Highly promises precision with its advanced microprocessor technology and digital thermometer. Test results are clearly and easily displayed on an LCD screen. Additionally, this handheld TDS water meter saves results for later reading, and the unit shuts off automatically after 10 minutes idle period to conserve battery life. The TDS meter measures between 0-9990 parts per million. From 0-999 ppm, the results are shown in increments of 1ppm. From 1000 to 9990 ppm, the results are displayed in increments of 10ppm, as indicated by a blinking 'x10' display. This TDS water meter includes 2 x 1.5 V cell batteries, which have a lifetime of 1000 hours. Get the TDS Hand Held Meter With Carrying Case from HM Digital for only $27.75! Use this TDS meter to make sure your water filter is working properly and that you are enjoying the purest water!

For more commercal applications or dual TDS and EC meter, look at this product, HM Digital COM-100

Inline and Commercial TDS Meters

Several products exist that can be installed on under sink and aquarium Reverse Osmosis systems that allow to constantly see TDS of water, including before and after the RO membrane. This usually helps to identify if your system or membrane works and time to replace it. Check out DM-1 Inline Dual TDS Monitor by HM Digital.

Inline TDS Meter on RO System

Commercial and Industrial TDS meters are used industry-wide by many water purification companies, utilities, manufacturing and a lot of businesses that use commercial or industrial Reverse Osmosis water filtration systems.

Commercial and Inline TDS Meters

Video Content about TDS

Video content, TDS Water testing

TDS Water testing, TDS and Electrolysis


Commercial or Industrial TDS controllers can be big. Here's example of one:

TDS Water Meters


TDS Water Meters


Perfect Water, hard day of work deserves a rest in a perfect environment. Yes, we like that one too.

TDS Water Meters

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