Safe water: self-cleaning filters

We live in a time in history where our planet’s resources are being exploited as probably never before. Perhaps the most important of these resources is water, blue gold, which gives us a vast amount of benefits, last but not least the productivity which results from the correct management of its cycle. The quantity and quality of water are progressively deteriorating in many regions, leading us to strive to find strategies and instruments to mitigate its waste and to improve its virtues. Improving quality means getting water that is safe for the use required of it, whether household or domestic.

“Normally variable amounts of dissolved and/or suspended
substances are found in primary waters, called impurities”

Primary Waters

“Primary waters” are those normally found in nature, used to meet both vital needs and production requirements. Primary waters come from sources, aquifers, rivers, lakes, rainwater etc. and should ideally be without contaminants.
Normally variable amounts of dissolved and/or suspended substances are found in primary waters, called impurities.

The most frequent types of impurities present in waters consist of:

a) suspended substances such as sand, clay, organic debris: they make water cloudy or opalescent.
b) dissolved substances, such as mineral salts and organic substances: they are generally invisible to the naked eye; in particular, alkaline-earth salts (calcium and magnesium) are at the base of water hardness. Often, primary waters, due to the fact that they contain these impurities, must undergo mechanical, physical or chemical pre-filtering treatments, suitable to make the H2O compliant with the requirements for the use for which they are intended.

Filtering and Pre-filtering

One of the most commonly used filtering and pre-filtering methods of primary waters consists of a system of one or more filtering modules placed in series one to another holding cartridges of different materials to purify the water
from the unwanted substances and to make it safe for the use that must be made of it.


As liquid continually passes through the filters at a certain pressure, the cartridges are subject to deterioration and must be cleaned and/or replaced. These operations are not always easy to do, also for logistical purposes, and they are expensive when we’re talking about cartridges of a certain quality. However we can find self-cleaning filters on the market, that lengthen the life of the cartridges and considerably reduce maintenance costs.

… “the most commonly used, simple and with excellent qualityprice
ratio are those with spring-operated back-wash technology
with descent of the cartridge …”

Self-Cleaning Technology

A self-cleaning filter can work with several types of principles. Various types can be found on the market, more or less complex and in different price ranges. Limiting the quest to mechanical self-cleaning filters, the most commonly used, simple and with excellent quality-price ratio are those with spring-operated back-wash technology with descent of the cartridge: when needed, the filter is quickly freed of sediments by opening a valve located at the bottom of the cup, moving the internal cartridge downwards. This movement inverts the flow of water crossing the cartridge; in just a few seconds, the filter is completely cleaned from all impurities trapped inside. To efficiently clean the cartridge, simply open the valve a few times for about ten seconds and you’re done.

“The solution that offers the best advantages is a self-cleaning
filter in clear plastic…”

Types of materials, technical features

Self-cleaning filters can be built in different materials, such as metal (perfect when water pressure exceeds 10 bar) and plastic, which can have different sizes and filtering capacities (expressed in micron). The solution that offers the best advantages is a self-cleaning filter in clear plastic, with a good size (at least 400 mm) and filtering between 50 and 100 micron. Clear plastic has the advantage of allowing the user to check the status of the filter immediately even at a distance, to intervene when needed.

Types of configurations

As we mentioned, the self-cleaning filter can be inserted into a more complex system with finer filtering downstream with cartridges that require further refining (up to 5 micron). These configurations can have two or three stages; the sturdiest are the single block systems which, in addition to the selfcleaning filter, are coupled with cartridges that block the smallest sediments and/or that affect smell, taste, colouring, pesticides, organic compounds etc. There are specialised manufacturers that supply users with Kits already consisting of two or three stages based on the sediments that need to be blocked to obtain water safe for the use to be made of it.

“When the pressure is not constant, it is advisable to use selfcleaning
filters with pressure gauges installed on the head…”

Installation

It is not particularly complicated to install the self-cleaning filter, though some components, such as water pressure, need to be carefully assessed. When the pressure is not constant, it is advisable to use self-cleaning filters with pressure gauges installed on the head so as to measure the inlet and outlet water pressure on the filter. This also allows us to understand how the filtering cartridge is performing, therefore if it is dirty and whether or not it needs to be cleaned.

In the presence of high pressure peaks (beyond 8 bar) the filter or filter system could be damaged. When installing the system, expansion vessels should be applied (downstream and upstream depending on the type of plant) to avoid the classical water hammer which would jeopardise the filtering system. As mentioned above, single-block systems, in addition to their sturdiness and reliability, also allow the installer to make couplings between filtering modules, thus making the job much quicker and safe

Certification

A certified product is a quality guarantee for the customer. This is why it is always advisable to choose a type of product with even more than one certification regardless of the Country or territory where it is mandatory. The certification undisputedly states that the product has undergone specific tests by third-party certification bodies confirming its quality. Without a doubt global companies, operating on a variety of markets, are those that provide their products with the most certifications possible.

“Self-cleaning can also be used to filter waters coming from wells
or tanks…”

Fields of application

Self-cleaning filters can be very versatile and useful both for household and industrial use with the purpose of obtaining a type of water that is safe for the required needs.
In some Countries with green environmental policies aimed at avoiding the waste of resources, these filters are widely used to improve rainwater and to make it available for technical uses.
Self-cleaning can also be used to filter waters coming from wells or tanks in countries where the water supply is discontinuous. Self-cleaning filters can be useful in farming to water fields or for rearing animals.

Advantages of using a self-cleaning filter

• Reduced maintenance: helps to save money
• Protection of the cartridges downstream helping to save money