Why do I have to use a filter for drinking water? The Municipality or the Community is not responsible for taking care of its suitability?

Municipalities and Communities make significant efforts to provide clean and potable water, free of particulate suspended matter and undesirable substances, chlorinated to destroy bacteria and viruses. After the purification and quality control of the water by the Municipality / Community, the water travels through piping networks where it is not possible to control its contamination by dirt, rust, or dangerous metals such as lead, from the old networks. Moreover, testing for insecticides and pesticides in water sources may not be continuous due to the complexity of these analyzes.

Therefore there is a need to purify the water at the point of use for the following reasons:

  • aesthetic reasons, with the removal of rust, dirt and other suspended solids, the removal of the unpleasant odor and taste of chlorine
  • hygiene reasons, by removing organic substances (insecticides, pesticides), hazardous metals (lead), derivatives of the reaction of chlorine with organic compounds (halogenated hydrocarbons), microbes, viruses, possibly even radioactive substances.
How many categories of filters are there?

The filters are divided into: a. central supply filters b. drinking water filters

More specifically :

A1. Filters for dirt / rust filters, suspended particles

A2. Filters for dirt / rust, suspended particles – chlorine, organic substances

B1. Filters for dirt / rust – chlorine, organic substances (below or on top of the kitchen counter)

B2. Filters for dirt / rust – chlorine – organic substances – microbes – lead – chemicals (below or on top of the kitchen counter)

B3. Reverse Osmosis system with retention of more than 97% of all harmful substances (under or on top of the kitchen counter).

How expensive is a water filter?

There are products in the market with large differences in quality and different origins. Therefore there are many “prices”. A careful market research will prove that “cheap” products without support and guarantees are always “expensive”. When it comes to products that protect our health, what matters is quality. To the extent that we now pay close attention to “what we eat” we should also focus on “what we drink”. Therefore the installation of a water filtration system is necessary.

The efficiency of each filter and especially of the filter that contains activated carbon depends mainly on 2 factors:

  • water flow through the filter, i.e. how fast the water passes through the filter
  • size of the filter, i.e. available surface for retention.

The small filters that are placed on the faucet have a very small surface for retention and therefore in order to be effective the water flow must be small so that there is enough contact time for cleaning.

What should I pay attention to, when choosing a filter or water purifier?

We must ask the supplier and carefully read the manufacturer’s technical specifications which refers to the operation of the filter or purification device and its recommended conditions of use, i.e.

  • what it removes from the water
  • the size of the pore
  • if it contains activated carbon
  • the capacity of the replacement cartridge
  • water flow during use
  • location of installation
  • maximum and minimum operating pressure
  • maximum and minimum operating temperature
  • certificates from international or national organizations
What does a graded density filter mean?

The graded density filter means that the water is filtered throughout the depth of the filter, i.e. the filter pore size is reduced as the water goes deeper inside the filter. This technology utilizers the use of all the filter material for filtration (all the depth of the filter) and thus increases the filtration efficiency and the life of the filter.

Why are the melt blown graded density polypropylene cartridges better than the string wound cartridges?

The water filters for the removal of dirt, rust and other suspended particles use filtering media such as:

α) metal sieve

β) woven string

γ) material in compact block (eg ceramic, polypropylene)

δ) graded density polypropylene

More specifically:

a) The metal sieve filters the water on the surface of the filter (sieve) and has relatively large pores (80microns).

b) The woven string filters the water mainly on the surface of the filter (woven string) and less on the inside of the woven material.

c) Compact material block (such as ceramic or polypropylene) filters the water mainly on the surface and less inside.

d) Polypropylene of graded density has pores that progressively become smaller (for example down to 5microns) and it filters water both on the surface and inside the cartridge.

Why do filters not retain dirt and rust and allow them to escape?

When a filter allows dirt or rust to pass, then one of the following may occur :

  • the cartridge has a very large pore size while the dirt and rust are smaller in size.
  • the cartridge is not installed correctly and some of the water passes through the filter without passing through the cartridge (partial by-pass of the cartridge).
  • the cartridge is not of good quality and either allows the water to pass through without being filtered or changes shape (deforms) with the pressure fluctuations of the network – common in the spiral wound type – and releases the already retained dirt.
What does ``micron`` mean when we talk about ``pore`` size of the filter cartridge, ie retention size?

“Micron” is a unit of length: 1 micron is depicted with the Greek letter “μm”, i.e. 1 micron is 1μm.

1m is equivalent to one millimeter of a millimeter, ie one millionth of a meter.

That is: 1 meter = 1000 mm (1m = 1000 mm)

1 mm = 1000 microns (1mm = 1000μm)

therefore: 1 meter = 1,000,000 microns (1m = 1,000,000 μm)

When the spare part of a filter has a pore:

1 micron  can hold solids larger than 1 micron

10 microns  can hold solids larger than 10 microns/u>

25 microns can hold solids larger than 25 microns

Examples : 

Human hair size (diameter) = Over 20μm

Flour = more than 1μm

Cigarette smoke = over 1 μm

Bacteria = more than 0.1 μm

Filter cartridges have many grades of ``pores`` (1 micron, 5 microns, 25 microns, etc.). How do I choose the right cartridge?

The service life of cartridge depends mainly on:

  • the water quantity, ie how much water passes through the filter daily
  • the degree of purity of the water, ie if the water contains a lot of dirt, rust and other suspended particles
  • the pore size of the filter

When the water is very dirty, that is, it contains a lot of dirt, rust and other suspended matter and the cartridge we use has a small pore, then the cartridge will clog quickly. Of course for the same water quality and the same cartridge, the more water passes through the filter per day, the faster it will clog.

The service life of cartridge decreases when :

  • the water quantity passing through the filter per day is high
  • the water is dirty
  • the pore of the cartridge is small

It is therefore recommended:

  • for central water supply filters (large water flow and water quantity) and relatively clean water to use cartridges of 5μm or 25μm
  • for central supply filters and relatively dirty water to use cartridges 25μm
  • for drinking water filters and relatively dirty water to use cartridges 5μm
  • for drinking water filters and relatively clean water to use cartridges 1μm

The ideal solution is to install a cartridge 5 to 25μm in the central supply and a cartridge 1 to 5μm in the drinking water faucet.

How do I understand that the useful life of the cartridge has come to an end?

As the cartridge accumulates the dirt it cleans from the water, its pores fill up and the water finds it difficult to pass through. This difficulty causes the pressure and water supply to gradually decrease when we turn on the faucet.

What is activated carbon, in what forms is it and how does it purify water?

Carbon is the key element of organic matter. The carbon used in water filters can be of inorganic (mineral rock) or organic (eg coconut) origin. The carbon is subjected to a suitable cleaning treatment so that its surface area increases in relation to its volume and this is how activated carbon is obtained. It is typical that 1 gr of activated carbon has an area of 1000 m2. Activated carbon has the property, with a natural process called adsorption, to attract and retain on its surface various chemical compounds such as chlorine, its derivatives and organic compounds such as insecticides and pesticides. Thus the water that passes through a layer of activated carbon is freed from its unwanted components. Activated carbon is used in two forms:

  • granular form, is in the form of ‘powder’
  • solid form, is in the form of a compact piece (block) with a fixed shape

This second form of activated carbon also achieves the filtration of suspended particles (dirt, rust)

Does the water filter remove inorganic salts?

The only water filters that remove inorganic salts (i.e. hardness salts) are those that contain a special resin and the reverse osmosis system. Some special filter cartridges contain polyphosphate crystals that prevent the deposition of salts in pipes and appliances. Another technology that prevents the deposition of salts is magnetic softeners.

Why does the filter cartridge often turns green?

The filter retains dirt and rust and other suspended particles that can carry various microorganisms. Some microorganisms (eg algae) when they grow, they produce plant like material, i.e. “greenery”. These microorganisms need food and sunlight to grow. The food comes from the materials that have been retained on the filter.

Could the carbon filter used for drinking water and where bacteria and chemicals accumulate, become a breeding ground for microorganisms and a source of infection?

The carbon filter could become a source of infection. For this reason it is recommended that the water does not stand still in the filter for more than a few hours. Otherwise it is recommended to let the faucet run for 1-2 liters before taking water for drinking and other uses.

How good (effective) is a small filter placed on the faucet?

The efficiency of each filter and especially of the activated carbon filter depends mainly on 2 factors:

  • water flow through the filter, ie how fast the water passes through the filter (liters / minute).
  • size of the filter, ie available surface for retention.
What is best to use? Filter with transparent or opaque cover?

The filter with a transparent cover allows easy inspection of the filter at a glance. Instead, the filter with opaque cover must be opened to see its condition.

On the other hand, the filter with a transparent cover allows the passage of light which promotes the growth of certain species of microorganisms (eg algae), while the filter with opaque cover does not allow them to grow. It is therefore recommended that, in areas exposed to sunlight or other light, a filter with an opaque cover be installed.

Why activated carbon filters should not be installed in the main supply of the house or apartment?

The drinking water of the network is regularly chlorinated by the Municipality or the Community with the aim of destroying all pathogenic microorganisms. The presence of chlorine is therefore important until the time we use the water. Unfortunately, chlorine and its derivatives give the water an unpleasant odor and taste. Activated carbon removes chlorine and its derivatives and significantly improves the taste of water. However, the removal of chlorine allows the growth of pathogenic microorganisms. It is therefore recommended that activated carbon filters be placed before the drinking water faucet and not in the mains supply, especially if the mains supply connection is away from the drinking water faucet. In any case, we must let a quantity of water “run” from the faucet before using it.

Is it possible for two or more apartments or an apartment building to have a common central supply filter?

It is possible to use a common filter in two or more apartments or in an apartment building. It is obvious that a larger filter and a suitable cartridge size should be selected depending on the desired result.

What is water hardness?

Hardness is the concentration of dissolved calcium and magnesium salts in water. Hardness is not harmful to the human body. However, it creates problems in the water network, in the devices that use water and in the efficiency of water as a means of cleaning.

More specifically :

  • Calcium and magnesium salts are deposited in water pipes but also in appliances such as water heaters, washing machines or on the dishes, where they create ‘scale deposits’ (“lime scale”).
  • Scale deposits reduce the flow of water resulting in a gradual drop in pressure.
  • Hardness salts reduce heat exchange so more energy is needed in the water heater or washing machine to heat the water.
  • Hardness salts bind part of the detergent when cleaning clothes or dishes, so more detergent is needed for cleaning.
  • The same happens for the soap and shampoo used in the bath so that we do not feel completely clean after the bath.
  • Hardness salts remain as white-gray spots on drinking glasses and dishes.
How do we make sure we find replacement cartridges for our filters?

The people who introduce the products “Hydravgis” in the Greek market have been dealing with the plumbing related products, as a family, since the 1960s. Water treatment is the professionally practiced in Greece and abroad by one of the executives of our company.

Therefore the products and the company have the reliability that guarantees the smooth supply of the market with replacement cartridges and spare parts.

What does NSF certification mean?

NSF = National Sanitary Foundation

It is a non-governmental, international organization established in the USA. It has laboratories for the control and certification of equipment used for water purification for residential or commercial use.

Any reputable manufacturer who claims that his/her equipment can reduce the concentration of unwanted and / or harmful substances in the water, addresses him/herself to the NSF organization, which, after examining the equipment and checking the specifications in the laboratory, certifies that the equipment performs according to the claims of the manufacturer. At this point the manufacturer is entitled to affix the NSF stamp to the product.

Our technical store “Simos Nalbantis” has been operating for 60 years. Since 2000 the scope of operation has been extended to the field of water filters under the name “Hydravgis”.
During this period of 20 years we have gained a lot of experience in this field, resulting in the offering of products with excellent quality and specifications, products that solve water quality problems.
We transaction our business responsibly and effectively, providing benefits to our partners, the society and the environment.

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