Best digital TDS meter for the money

Many of the current reverse osmosis systems do not come with a TDS meter for you to take the reading of your water. It is not really a critical tool to have but I like to measure the before and after quality of the water so I got one when I purchased my first RO system. Since then, I have been using it to monitor the water and whether the RO system is still working well. Given the small cost a digital TDS meter, I think it is a worthwhile investment. If you are looingk for one, here my recommendations on the top digital TDS water quality meter for 2015.


HM digital TDS meter review

Summary review

best digital tds meter for the money 2The HM water quality testor is, hands down, one of the top rated and best device in its category for 2015. It received a staggering 450+ reviews with most of them being very positive. If you are looking for the top brand in this product line, this is the one to get even though it might not be the cheapest.

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This TDS-4 model is actually a newer version of the very popular TDS-EZ model which received almost 1600 in reviews. The main improvement from EZ to 4 is the temperature compensation function, which makes it already accurate reading more consistent. For those who might not know, temperature differences can cause fluctuations in TDS reading, although the differences might not be very large. However, to have consistent readings, controlling for temperature is important.

Now that we know the difference between the HM TDS-EZ vs TDS-4, let’s look into more details on why I purchased this particular model. When I was first shopping around, the most important criteria I was watching out for is the meter’s accuracy. If it isn’t accurate, it defeats of buying one, wouldn’t you say?

So, TDS-4 stood out as the water quality testor that had the most accurate readings from the reviews I read. In particular, it had a stated accuracy of +/- 2%, which is more accurate than any other brands I have seen. The temperature compensation just make the deal sweeter as I know the readings will not be comprised via changes in the weather.

When I first got it, I immediately test it on my water quality level. Tap water was in a predictable 200+ ppm range. After installing my Home Master, the ppm readings from this meter dropped to less than 10. Needless to say, i am happy with both the RO system as well as the TDS meter. To make sure it is really accurate, I even took the meter and test it on the water quality from a watershop. Since it had better commercial equipment, the water quality should be higher. That is indeed the case, as the meter show a remarkable 2ppm reading from the water purchased from the watershop. Happy with these results, I would say the TDS meter has great accuracy.

Outside of the accuracy, I like this device slim design. It is easy to store and carry around. In fact, it has become a habit of mine to test the quality of the drinking water in new places that I go to, such as restaurants, friend’s home etc.

However, you do need to be careful with this device. Only the tip of the meter should go into the water as the whole thing is not waterproof. If you accidentally drop it in your water storage tank, you will probably need a replacement as the water will sip into the device and interfere with the readings. I found out about this when my colleague, who had a RO system as well, complained to me about the TDS-4 after I recommended it to him.


Benefits of a TDS meter

Besides knowing the quality of your water, there are a couple of other benefits that I realised after using the digital TDS meter for a while.

First, it saves you money by letting you know when to change filters. Although the RO systems have a recommended change date, it is best to test it out yourself. Simply divide the ppm reading from your RO water to the tap water and see if it exceeds 20%. If it doesn’t, save the money and wait for a longer period before changing the RO filters.

Second, taking regular ppm readings can alert you to any potential malfunctioning of your RO system. An Amazon reviewer said he was shocked when he got a reading of 220 ppm from his RO system. After checking the system, he found out about a punctured diaphram, which is the cause of the high ppm readings. This problem is definitely not noticeable as the water is still coming out so you wouldn’t know it unless you take regular ppm readings.

Third, you can use the TDS meter on your office and see how good or bad your office water is. If it is bad, then prepare to take some water from your home RO system and drink from that instead of from the office. This usage can be applied to any area outside of your home so that you can easily check the quality of the drinking water.


Cheap TDS digital meter

cheapest TDS meterFor those who only want to get the cheapest TDS meter, then the Mudder dual meter is the one that I can recommend. Initially, I was thinking about just buying the cheapest mode I can find since I don’t think I will be using it as frequently as I am currently.  This was the model that I was considering. It is the only model that is priced under $10.

However, I change my mind because the reviewers seems be find calibration to be a problem.  After reading through the comments, I realise the device can be recaliberated but it needs a go through a 3 step process. I don’t think I have too much patience for that kind of thing since I just want to measure the water as conveniently as I can. If you don’t min going through the motion, this is a good cheap option to consider.

Another thing that bugged was the lack of explanation on how the TDS was calculated. There is around 3 ways to derive TDS and the one I bought had an explanation of what is their method. The Mudder model didn’t have this explanation so I can’t really trust the readings I will be getting from the device.

After weighing the pros and cons, I decided to go with the more expensive and reliable TDS meter since the absolute dollar amount isn’t that much.



After using the TDS-4 for quite some time, I find it to be reliable and easy to use. Given that it has help me to know the correct time to change my filters, I would say it has already paid for itself many times over.

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