With the use of modern technology, there are gadgets that you can now use that help you have a more healthy environment. I’ve talked before about air quality monitors. Today I want to tell you about water quality testers. After all, about 60% of our body is made up of water, and so it is important that you are drinking good quality water. Back home in the UK, we are used to just drinking water from the tap. However, here in Thailand, our lives revolve around drinking filtered water or bottled water. We would never drink straight from the tap even though the Metropolitan Waterworks Authority assures us it is safe to drink. For general purposes, I use a water filter in my house. But, how to know when it is time to change the filter? As I neglected to note down the last time that I changed my filter, I decided to buy a Xiaomi TDS Water Quality Tester Pen to see if the purity remained good. This is the review of that tester pen and my experience of using it in my daily life.
Xiaomi is a well-known electronics company based in China. They make smartphones, laptops and other electronic devices like the MI Air Purifier 2 which I reviewed earlier. The Mi TDS Pen Tester is another of their products. As the name suggests, it looks a bit like a ballpoint pen though it is slightly bulkier. There is a cap at one end which protects the electrode sensors. The cap is also where you put the water that you are testing. The other end is for two replaceable button batteries. There is a small LCD screen which unfortunately isn’t backlit. So, not always that easy to read. To turn on the meter, just press the button. The reading should be zero. It will turn itself off after a few minutes or you can just press the button again.
TDS stands for ‘total dissolved solids’ which includes Soluble salts such as calcium, magnesium, etc, Ionic organic compound such as ammonium acetate, sodium, etc., and Metal ions such as chromium, zinc, lead, copper, etc. TDS is measured in PPM which stands for ‘parts per million’ or just mg/L which stands for ‘milligrams per liter’. Basically, the lower the reading, the higher the purity of your water. WHO says that any water with a reading of less than 300ppm is regarded as good to drink. Though you can drink any water up to about 1,000ppm. In theory, that is. It may contain harmful chemicals. More about that in a moment.
Lowering TDS is done through reverse osmosis (RO). A good RO filtering unit can reduce dissolved solids by more than 90%. Bottled water sold in Thailand and some home water purifiers may use RO together with ultraviolet treatment and/or ozone treatment. UV Water Purification systems remove 99.99% of bacteria and viruses. Ozone purifiers can remove 99% of all biological pathogens including Giardia and Cryptosporidium. The TDS meter pen can check for the purity of your water, but it cannot check for things such as bacteria, viruses and other harmful substances. For that, you will need a laboratory. All I wanted to do with the TDS meter pen was to see how well my water purifier was working. Was it reducing dissolved solids by at least 90%? First I tested my tap water which had a reading of 161ppm which is pretty good compared to some countries. I then tested my purified water and that was only 6ppm. So, I can presume that it is still doing a good job.
The Xiaomi Mi TDS Pen is easy to use. The meter pen comes with batteries already installed so that you can use it straight out of the box. All you have to do is put some water you want to test into a cup or the pen cap. Then press the button on the pen to turn it on making sure it says zero. Then put it into the water. You only have to wait a few seconds. Unfortunately, there is no hold button and so as soon as you take it out of the water, it quickly goes back to zero. So, putting the water into the cap is more efficient. In the photo above, the Mi TDS Pen is pictured together with the more bulkier TDS EZ which I bought a few years ago on Amazon. They are much alike, though the TDS EZ has a hold button which makes it easier to see the results. Their test readings were very similiar. Particularly for purer water. However, the large the number, say for example 200+ ppm, then the bigger the difference between them. But only by about 5ppm.
Once I had tested my tap water and filtered water, I naturally wanted to then check bottled water. Which brand has the purest water? But, before I give you the results, I need to give a warning. Natural spring water or mineral water will give a high TDS reading of say around 300ppm. Other bottled water may have some minerals added. Not just for health, but for taste too. Although my purified water having a reading of only 6ppm is very good, it is also tasteless and doesn’t contain any minerals that your body may need. But, I don’t care so much, I can easily get minerals from eating a balanced diet. So, here is the result of these popular brands of bottled water sold in Thailand. You might be surprised by some of the results: (1) Crystal 20ppm, (2) Chang 122ppm, (3) 7 Select 5ppm, (4) Singha 344ppm, (5) Nestle Pure Life 220ppm, (6) Namthip 25ppm, and (7) Avias 36ppm.
I need to emphasize again, that a higher TDS reading doesn’t mean unsafe water. It just means the water isn’t pure and has been fortified with something. As you can see from the readings I took, 7 Select, which is one of the cheapest brands available, had a reading of only 5ppm. At the other end of the scale was Singha Drinking Water with a reading of 344ppm. Which was very surprising. I actually went to a different shop to buy another bottle just to make sure. I also tested with the other TDS pen I had. The results were still high. I am not saying the water isnt clean. I am just saying it is not pure. Something has been added, but I cannot tell what as there is nothing mentioned on the label. It only says NSF certification (National Sanitation Foundation) which is an international standard of quality. Chang water and Nestle Pure Life also has this certification. The question is whether we trust them or not or just go for the purest water available. After all, as I said before, we can get our minerals from eating a balanced diet.
I bought the Xiaomi Mi TDS Pen on Lazada for just over 200 Baht. Here is a link to for all TDS pens on Lazada. Of course, other shopping venues are available. In every case, be careful that you are not buying a counterfeit item. I like the brand Xiaomi and I think many of their products are stylish. Their TDS pen seems reliable and is small and light enough to carry around on my travels. The price is not expensive too. If you have a water filtration system at home, I would strongly suggest that you buy a TDS pen to check on the purity of your water. You will find it invaluable. After I mentioned to a Thai friend of mine that I had bought a TDS meter pen, she asked me to test the filtered water in her house. Which I did and the results were a high 165ppm. This is basically the same as her tap water and showed me that her filtration system wasn’t working at all. So, basically, she had been drinking tap water thinking it had been purified by filters. She has now ordered some replacement filters.
As before, if you have had experience with this TDS pen or any others, please post your thoughts in the comments below. I’m also interested to have your opinion about the bottled water that I tested. Why did some test so high? Are they spring water or mineral water? There are also other affordable water quality testers on the market that test things like pH and EC. Do you have any experience with these? Thanks for reading and I hope I have helped some people.