Friends who need drinking water quality at home often see the figure of TDS test pen when choosing water purifiers, and the displayed value is often one of the criteria for judging the water quality of water purifiers.
Who is TDS? How do some water purifiers make the TDS value of tap water from hundreds to double digits or single digits?
TDS is total dissolved solids,The abbreviation of "total dissolved solids",Its numerical value represents the mass of dissolved solids in one liter of water, and the unit is mg/liter. The measuring tool is the pen-shaped TDS tester that we often see in evaluation and publicity.
Here we will find a BUG:The value displayed by TDS tester is the total amount of solid matter dissolved in water.
In fact, there are many kinds of solid substances in tap water, such as minerals and trace elements, calcium and magnesium salts that are easy to form scale, sediment dissolved in water, scale peeled off from transportation pipelines, rust and so on.
Because of the complexity of solid types, TDS meter can not accurately distinguish whether its composition is beneficial or harmful to human body.
For example, the TDS value of tap water we use every day is about 100-200, and the TDS value of mineral water sold in supermarkets is about 100, but mineral water can be drunk directly, but tap water is not.
Such a situation will inevitably be confusing. What is the significance of testing TDS value by water purifier? However, before further explaining this question, let’s take a look at the numerical requirements of national standards for tap water quality.
According to the limited requirements of TDS value of drinking tap water in the Hygienic Standard for Drinking Water in 2006, the TDS value of domestic water should be less than or equal to 1000 mg/L.
What kind of numerical concept is this? Generally, the TDS value of tap water in new residential buildings is 100-200, and the TDS value of tap water in older residential buildings will not exceed 500.
Generally speaking, as long as the urban water supply is not affected by various disasters, the daily drinking water will basically not exceed this limit.
However, this tap water quality requirement cannot meet the standard of direct drinking water. We were taught by our parents to boil water before drinking, and we didn’t have the habit of drinking tap water directly.
Moreover, the cost of direct drinking in waterworks is quite high, and there is also the problem of secondary pollution during transportation, which is not only unnecessary, but also difficult to achieve.
With the development of life, people more or less have certain requirements for the quality of tap water, not necessarily for direct drinking, but also for removing impurities, odor or scale in water, which reflects the existence value of water purifier.
Back to the original question, why does the water purifier evaluation show the TDS value of water quality?
The answer is very simple, in order to show the ultra-high filtration capacity of the water purifier, because it is difficult to tell whether the solids in the water are good or bad, so it is better to filter them all at once. There are no impurities in the water, so it can be drunk directly.
Only RO reverse osmosis water purifier can achieve such strong filtration ability.
This kind of water purifier fully filters all impurities including bacteria, viruses and microorganisms in water through the filtration precision of RO reverse osmosis membrane of 0.0001 micron. Only water molecules and a very small amount of trace elements can pass through, and the TDS value of naturally produced water is only single digits.
In addition to the reverse osmosis water purifier, there is also a common ultrafiltration water purifier on the market.
This kind of products can only filter tap water simply, remove large-particle impurities such as sediment and rust, and eliminate odor, while bacterial viruses and scale will still remain in the produced water.This kind of products can’t pass the TDS test to judge the water quality standard.
Smart brands will not introduce the specific differences of such water purifiers to consumers in detail. Common reverse osmosis water purifiers will promote "pure water" and "direct drinking", while ultrafiltration water purifiers will promote "no power consumption" and "mineral water" as features.
So is it necessary to choose reverse osmosis without thinking when buying a water purifier? Or choose ultrafiltration to drink "mineral water"? Let’s analyze it for you:
Reverse osmosis water purifier:
Advantage: excellent filtering effect, and that produce purified water can be directly drunk.
Disadvantages:
1. The reverse osmosis water purifier will produce wastewater.
2. When working, the water purifier pressurizes the water supply, which requires power consumption.
3. The filter element of reverse osmosis water purifier has a general service life of 3 years, and needs to be replaced when it expires, so the price is high.
Applicable environment:The water quality is hard and prone to water pollution problems, such as coastal salt tides and flood-prone areas.
Applicable people:There is a high demand for drinking water quality, especially for families who need to take care of infants and frail elderly people.
Ultrafiltration water purifier:
Advantages:
1. It can retain minerals in water, and is suitable for making tea and coffee to enhance the taste.
2. It can be used immediately after installation, and no electricity is needed.
3. Some product filter elements can be reused, and the replacement price is lower.
Disadvantages: tap water can only be simply filtered, and it needs to be boiled and drunk, which will produce scale.
Applicable environment:The tap water has many impurities, the water quality is soft, and it is not easy to be polluted.
Applicable people:There is no high requirement for water quality, and it is only necessary to simply filter impurities and odors at a lower cost to meet the needs of families who wash vegetables and cook daily.
Summary:
Although TDS meter is a reference for visually displaying water quality, it can only reflect the water purification effect of reverse osmosis water purifier.
As for the common ultrafiltration water purifier, the reference value of TDS meter is not significant. The simplest and reliable method is to boil tap water before drinking. I hope this article can help everyone who is buying a water purifier.
