Although we may be tempted to think that water flowing from deep within Mt. Gumgang is the
best, would you believe that the city water we so often mistrust is actually the best water for boilers?
  Of course, city water is far from perfect. As the water passes through the precipitation and
filtration processes at the filtration plant, some particles are not completely removed, and the clarity of the water source (i.e. river water) also greatly affects water quality. After all, aren't rivers murky and muddy during the rainy season?
  However, since the filtration plant quality standard of city water is set to be safe for people to
drink, it is also perfectly fine for boiler.
  On the other hand, oil and gas boilers have very complex water tank internal structures that
require scale removal through chemical treatment (although chemical treatment is often insufficient for complete removal) and a separate city water filter device in order to have a lifespan of 5 to 6 years. These boilers can be used with reasonable confidence only with filters to block out fine particles and an ion exchange purifier to remove minerals. However, the costs of purification system installation and regular filter replacement are considerable, and there is the additional hassle of needing to periodically add salt to the ion exchange purifier.
  Actually, in order to purify water properly, numerous complicated processes are necessary.
For example, steam turbine boilers in a power plant go through the filtration stages of dissolved gas (dissolved oxygen, etc.) elimination, fine particle precipitation, filtration, solidification of solvent minerals, purification, etc. in order to protect the expensive boiler.
  Compared with oil or gas boilers, electric boilers have a simple water tank internal structure
with no need to install filters, and an internal cleaning once every three years or so will be enough to ensure quality performance.
  The problem lies in self-drawn water sources such as underground reserve water.
  There are countless organic particles, mineral elements, minute mud sediments, and other
chemical matters from the earth surface in underground reserve water. As the boiler boils this water, these fine particles build up a thick scale layer on the floor and sides of the boiler.
  In order to minimize this scale formation, blocking out fine particles and installing a filtration
system is highly effective, but another problem is the volatility of chemical elements.
  As these particles are boiled and evaporate, they combine with dirt particles from the water
and block the pipes and walls of the steamer. It is hard to prevent the inflow of such particles. Hence, when you are preparing food, it is best to avoid using underground reserve water in your boiler.
  The problem of scale formation is quite difficult and boiler manufacturers worldwide are
grappling with it. In fact, as a result of this very problem, many foreign companies are hesitant to enter the domestic market.
  It is not uncommon to see oil or gas boilers thrown away after only a year due to the usage
of underground reserve water. Fortunately, Korea's river water is soft water below level 6, so city water can be used without any harmful effects.