Have you ever wondered what is really in your glass of water?
It looks clear. It might even taste fine. But water is never just water. Every glass holds tiny invisible things that dissolved into it along the way. Scientists have a name for all of this. We call it TDS.
If you have children at home, this matters even more. Kids drink a lot of water. They fill bottles for school. They drink from the tap after playing outside. Knowing what is in that water helps you make better choices for your family.
The good news is that TDS is easy to understand. It is also very easy to measure at home. In this guide I will explain what TDS in water means, what a good level looks like, and how to do a simple water test yourself.
What Does TDS Mean?
TDS stands for Total Dissolved Solids. It is the total amount of stuff that has dissolved in your water. As water travels through rocks, soil, and pipes, tiny bits of other things dissolve into it. You cannot see them, but they are there.
These dissolved solids can include:
- Minerals such as calcium and magnesium
- Salts such as sodium
- Metals such as lead, copper, and iron from old pipes
- Nitrates from farming
- Traces of chlorine and other chemicals used to treat water
Some of these things are harmless. Some are even good for you in small amounts. Others are not something you want in your drinking water at all.
TDS is measured in parts per million, written as ppm. A reading of 300 ppm means there are 300 tiny parts of dissolved solids in every million parts of water.
What Is a Good TDS Level for Drinking Water?
There is no single perfect number. But scientists and health bodies around the world use some helpful ranges. The World Health Organization has looked at how TDS affects the taste of drinking water. Here is a simple way to read your result.
| TDS Level (ppm) | What It Means |
|---|---|
0 to 50 |
Very low. Extremely pure water |
50 to 150 |
Low. Clean water, common after good filtration |
150 to 300 |
Fine for most homes |
300 to 500 |
High. Water may taste off and leave limescale |
Over 500 |
Very high. Requires high filtration |
Water above 500 ppm is generally seen as poor quality for drinking. In Ireland, many areas have hard water. Hard water often shows higher TDS readings because of extra calcium and magnesium. That is the white crust you see in your kettle.
One important point. A low TDS number does not promise perfectly safe water. And a high number does not always mean danger. TDS tells you how much is dissolved in your water, not exactly what it is. Bacteria, for example, do not show up in a TDS reading. That is why the Environmental Protection Agency in Ireland runs full laboratory tests on public water supplies every year. But for a quick check at home, TDS is still a brilliant first clue. It is the fastest way to get a picture of your water quality.
How to Do a TDS Water Test at Home
This is the fun part. You do not need a lab coat. You just need a small device called a TDS meter. They look like a fat pen and cost very little online or in hardware shops..
Here is how to do your water test in four easy steps:
Step 1. Fill a clean glass with tap water. Let the tap run for a few seconds first. This gives you a fair sample.
Step 2. Turn on the TDS meter and dip it in. Place the tip into the water. Do not go past the maximum line marked on the meter.
Step 3. Wait a few seconds. Give the number on the screen time to settle. A little stir helps.
Step 4. Read and note your result. Write the number down with the date. Testing once a month shows you how your water changes over time.
That is it. In under a minute you know your TDS level. Test the water straight from your tap first. If you use any kind of water filter, test that water too. Comparing the two numbers shows you exactly how much your filter is really doing. In this video, we show exactly how it works:
Do Jug Filters Lower TDS?
Many Irish homes keep a filter jug in the fridge. They are handy and they can improve taste. But here is something most people never check. Independent testing shows that a typical jug filter removes only around 16 percent of the dissolved solids in water.
Why so little? Jug filters mostly use carbon. Carbon is good at grabbing chlorine, which improves taste and smell. But most dissolved solids simply pass through it. Metals, nitrates, and hardness minerals are too small and too well dissolved for a basic carbon filter to catch.
You can prove this yourself with your new TDS meter. Test your tap water. Then test the water from the jug. Most people are surprised at how close the two numbers are.
This does not make jug filters useless. It just means they do a small part of the job. If your goal is a real drop in TDS, you need a different kind of technology.
What Actually Lowers TDS?
The most effective home method is reverse osmosis. A reverse osmosis system pushes water through a very fine membrane. The holes in this membrane are so small that dissolved solids cannot fit through. Only clean water passes to the other side.
The difference is easy to see on a water test. Where a jug filter removes around 16 percent of dissolved solids, a good reverse osmosis system removes well over 90 percent. Tap water at 300 ppm can come out below 20 ppm.
At Renewell Water, this is exactly what our team measures at every installation. Our technicians do a TDS test before fitting the system and another one after. Customers watch the number fall in front of them.
If you want to bring your drinking water to a very low TDS level, the ArkkZ Water Filtration System is a compact reverse osmosis unit that fits under the kitchen sink. It filters the water you drink, cook with, and put in the kettle.
"We always test the water with the customer standing beside us. When they see their own tap water drop from 280 ppm to under 15 ppm, no sales pitch is needed. The number speaks for itself."
Simon Newell, Founder of Renewell Water
Testing your water is a small habit with a big payoff. Once you know your number, you are no longer guessing about your family's drinking water. You are making an informed choice. And that is always the best place to start.
