Basics about TDS
What is TDS?
TDS stands for total dissolved solids and is measured by a meter or sticker through conductivity. A TDS meter will measure all the charged ions(both positively and negatively) that are found present in the water. These ions include calcium, magnesium, nitrates, iron to name just a few. Other pollutants like Chlorine and becteria could not be tested out. So it's hard to tell from the reading simply to conclude the tested water good or bad, qualified or not qualified.
Why is TDS test helpful?
Now that TDS covers both good and bad things and something harmful could not be covered, will it be meaningless to do the TDS test, unlike the precice lab tests?The answer might be No.
In the real practice, the water source is confirmed instead of being unknown. For tap water and bottled water, they are from either lakes or rivers on the surface of the earth. Most of the solids inside tested out won't be healthy minerals. So we could generally tell from the reading if the water is clean or no and compare the tested samples.
(For the natural bottled water, things will be a bit different. Since they are either from mountains, springs or from underground whose sources have been fully testified with good things and protected. Thus, when doing the test, it's hard to compare this to tap water or treated bottled water.)
Another good thing about the TDS is that it could be used to tell the differences between filtered water and tap water. The bigger the difference is, the better the effectiveness will be.
Are there standards over TDS?
Actually no theoretically and yes practically. Many counties set a maximum TDS level allowed for the drinking water but the level varies a lot from nation to nation.There is no known minimum for drinking water. But there are maximum TDS restrictions(500 for EPA, 1000 for WHO). Generally, the higher the reading for the TDS is for the tap water, the more potentially for the water to be with problems.( Natural mineral is different as the source is underground or spring water). For these who want to to assess the water with TDS, the following could be some kind of reference.
TDS of Tap Water and Filtered Water in Shanghai
What is TDS reading for tap water?---We monitored the TDS readings for Shanghai Tap water over past few years. What we found over the tap water within the city proper in the past several years is that the TDS reading of tap water in Shanghai dropped significantly these years with the upgrade of treatment facilities and change of water source from Huangpu river to Qingcaosha reservoir along Yangtze River. (For the decreased solids, thinking about the smelly Huangpu river before, no one will believe the decreased solids are healthy minerals.)
What is TDS reading for Filtered Water?
It all depends on which kind of filtration is used. In the market, there are 2 kinds of filtration. One is in-depth filtration like the reverse osmosis( distillation is also in-depth treatment, but it's mainly used industrially.) It removes virtually everything. For water through the RO or distillation based systems, the reading for TDS will be less than 50. Bottled water is just of this type. Distilled water reads zero whileremineralized purified water reads about 30.
Basic filtration covering carbon absorption, ultra filtration, ionization is applied to virtually all other systems including whole house filters, water softeners, shower filters, faucet filters and so on. It removes either chlorine, or hard minerals or big sized things. No matter how many stages of filters are used inside, the filtered water will be with almost no change for the reading of TDS. Even by the time for their being used, the reading could possibly go high. However, this doesnot mean the systems are not working. After all, the solids will do no harm if not taken into our body.
TDS reading for Greenwave products
Greenwave recommends in-depth filtration systems for drinking and cooking water and basic filtration systems for cleaning water, and we sources products that way. For our Alatai, Betta and Clavo reverse osmosis systems, the reading of TDS in the water is less than 30. For other filters with tourmaline whose purposes are mainly removing chlorine, softening water and reducing part of the heavy metals, the TDS reading of the filtered water will be with no much differences.
Tips for TDS Test and Some Notes
Tips to do the test
Temperature will influence the testing results as it will influence the moving rate of the ions in the water. When doing a test, better to collect cold water or samples with same temperature. Before collecting a sample, to make sure the sample is representative, it‘s better to let the tap run a while( 30 seconds) first as the water inside the pipes could possibly collected something inside over a night or some time ahead. In terms of the quantiyt of water sample, 1 fourth or 2 fifth of a cup will be enough.
TDS reading is good to tell if the bottled water（not natural mineral ) is clean and if the reverse osmosis drinking water purifier is working properly. Howvere, even though the TDS reading of tap water or filtered cleaning water is high, it doesnot necessarily mean the water is bad.
It's normal if the TDS reading of tap water or simply filtered water is around 200. Though industrial reverse osmosis system is available, it will not be a good for its expensive upfront and post cost as well as its big space.
If your bottled water(not natural mineral) or purified water from either your individual reverse osmosis filter or your compound centralized reverse osmosis system reads over 50, that will mean the water is fake, expired or polluted. You are not recommended to drink that water again.
TDS test is very basic. Lab tests will be still needed if you want to know what kinds of pollutants are inside and how much each pollutant is in the water. Companies like labs, PureLiving and us all come help do the tests.