Stages of treatment to obtain potable water at home

Potable Water in the World

Unpurified water can be contaminated by pathogenic organisms, such as bacteria, amoebae and viruses, larval eggs and parasitic worms that cause diseases such as cholera, as well as it can be contaminated with chemicals that are harmful to health, such as waste industrial chemicals, pesticides, fertilizers, chemicals from the natural environment, such as arsenic, common salt. It is important to note that cholera can kill a person in a matter of hours if it is not treated in time [4] and it remains an endemic disease in 69 countries, an estimated 2.9 million cases and 95 thousand deaths from cholera per year [4] around the world.

1 in 3 people globally do not have access to Potable Water at home - UNICEF, WHO

Surface water sources such as ponds are normally contaminated by microbes, animal faeces decomposing organic material from the natural life cycle of wildlife, groundwater near cities or crops where pesticides are used is most likely to be slightly contaminated with chemicals used by the industry.

Rainwater captured with collection systems on roofs or small storage ponds is relatively the safest means of obtaining potable water [3], taking into account that the water must be allowed to flow in the first minutes of the rain to avoid collecting dirt from collection systems.

It is estimated that an average person needs between 20 and 50 liters of potable water a day, whether for drinking, cooking, personal hygiene and laundry [3].

If you do not have sources of potable water at home and you have access to raw water, you can make your own water purification system applying some sanitation techniques and be able to use it to drink, wash and cook food, reducing the risks of contracting some bacterial disease.

There are a variety of methods and technologies to treat water at home and make it drinkable, the methods or techniques that we are going to teach in this publication will not remove chemical contamination from the water since this process implies a more specific treatment depending on the type of contaminant. chemical in the water.

The treatment to obtain drinking water at home consists of 3 stages [5]:

• Pre-treatment and filtering stage.
• Disinfection Stage.
• Storage Stage.

Here is the Stages of treatment to obtain potable water at home to obtain pure water for drinking, cooking and washing food.

Pre-treatment and filtering stage

The pre-treatment and filtering stage to obtain potable water at home consists of 3 types, such as aeration of the water, storage for the settlement of impurities and filtration of the water.

Water aeration

Aeration consists of vigorously shaking the container containing the untreated water in order to allow oxygen bubbles to enter the water creating the following beneficial effects:

Oxygenation by agitation of water will allow the removal of carbon dioxide by combining the oxygen molecules added in the water by means of agitation or aeration.

It will allow the oxidation of metals harmful to health, such as excess iron, manganese to later be removed in the filtration and settlement process, the oxygen will create an electrolytic reaction of the metals and will cause their oxidation.

It is recommended that the stirring or aeration process be carried out for approximately 5 minutes and then let it rest for approximately 30 minutes so that the oxidation and sedimentation process of the suspended particles is completed.

Storage for impurities settling 

The condition of the water should be visually evaluated, if the water is too cloudy and you have enough time before consuming it and you do not have a home particle filter, you can let the water settle for about two days so that the contaminants settle, which reduces contamination and reduces the number of organisms that act as intermediate hosts for diseases such as guinea worm (dracunculiasis) infection.

A homemade filter to produce potable water removes impurity contamination from the water by physically blocking the particles and allowing the water to pass through.

Water filtration

The filtration process allows to eliminate the largest amount of particles contained in the water, more quickly than with the impurity settlement process, this can be done using three most common filtration methods, such as: membrane filters, filters of sand and ceramic filters.

Membrane filters

Membrane filters consist of several sheets of porous material that are used to screen or filter the water, separating the solid particles from the water, depending on the type of membrane material, larger or smaller particles can be separated.

In our home we can manufacture membrane filters as part of the process to obtain drinking water at home, using easily available materials, such as:

Several layers of clothing fabric, you must boil the fabric with running water before using it to eliminate any type of bacteria or biological agent.

Paper filters used to make coffee also serve as a filter membrane and are already sterilized.

New sterile valveless masks, type N95 are ideal to be used as highly effective filtration membranes.

The process is simple, you just have to place your homemade filtration membrane on the top of the container and gradually add the water you want to filter as it falls into the container.

Sand filters

The use of sand filters to obtain potable water at home is highly effective to remove suspended solids from the water and a large amount of biological agents, for this, coarse sand and gravel or stone crushed into small pieces must be used. Making a sand filter to make the water drinkable is very easy:

Necessary materials

A small bag of coarse sand.

A quarter of a small sack of finely crushed stone.

A bucket or container of water of approximately 10 liters capacity with a hole in the bottom or an extraction valve similar to the thermos of water used for camping or those used in baseball or soccer games.

Cooking pot of about 5 liters capacity.

Procedure to create the homemade sand filter

To start creating your potable water treatment system at home, you must sterilize the sand and the stone, bring water to boil and once boiling, add the sand, let it rest for a few minutes and remove it from the pot, do the same with the stone and you will have everything sterilized.

Fill a fifth of the 10-liter container that you have available to make the sand filter with the crushed stone and spread it over the surface then add the coarse sand up to half of the container.

With this, you only have to add the water you want to filter and open the valve of the container at the bottom to collect the water filtered by the sand and the stone.

Ceramic filters

Ceramic filters work by filtering the water by passing it through the cavities or porosities of the ceramic, which filters the smallest particles and allows the water to pass through.

Ceramic filters to obtain potable water at home are simple and we have several more common types, such as ceramic vase-type filters and Ceramic cartridge type filters.

Vase-type filters

They are simple vases in the shape of an inverted cone made of porous ceramic that, thanks to the effect of gravity, lets the water pass downwards and filters the particles or impurities, it is quite useful to obtain drinking water at home in an economic way, it does not take much complexity only the ceramic vase and a container at the bottom to collect the filtered water.

Ceramic Cartridge Filters

These filters to obtain potable water at home are a little more elaborate and more expensive than ceramic vase-type filters, however, the principle is the same, it uses gravity to let the water pass through the porosities of the ceramic and the purified or filtered water is collected at the bottom.

This filter consists of a cartridge the average size of a 750 milliliter water bottle, with a discharge hose, the filter is inserted into the container that contains the raw water and the discharge hose is placed at the bottom where you will find the other container that will receive the filtered water.

With a smaller filter surface than the ceramic vase filter, it is a little slower, but just as efficient at obtaining potable water.

Disinfection Stage

The disinfection stage consists of eliminating germs and bacteria using some methods or a combination of them, such as; boiling disinfection, solar disinfection and chemical disinfection.

Boiling Disinfection

Boiling water at 100 ° C (212 ° F) to obtain drinking water at home is an effective method to eliminate bacteria and microorganisms harmful to the human body, also called Pasteurization [6]. Between 65 ° C (169 ° F) and 80 ° C (176 ° C) most of the microorganisms harmful to the human body die, this method of purifying the water gives it a slightly different taste so it is recommended to shake the water (Water aeration) once it has lowered its temperature.

Solar Disinfection (SODIS)

Obtaining home potable water through solar disinfection, also called solar pasteurization [7], is a simple method:

Place the water in a transparent container sealed with a black background, on a sunny day it will reach about 65 ° C (169 ° F), which will eliminate a large amount of bacteria, you must leave the container for at least 24 hours of exposure to the sun and 48 hours on cloudy days.

The Sun´s Ultraviolet (UV) rays are also effective in removing a large number of batteries, which is why it is important that a clear container be used to let the sun´s rays pass through.

Chemical disinfection

There are a variety of commercial chemicals formulated to disinfect water and make it drinkable, chlorine is the most used for this task, with the right chemical product ratio in the water, most bacteria and viruses will be killed, however, some species Such as Cryptosporidium are resistant to chlorine, we can find chemical products to make water drinkable in the form of tablets, powder and liquid. The use of this type of product for water disinfection will depend on the manufacturer´s specifications for each particular product.

Storage Stage

If we convert tap water into potable water, the idea is to keep it potable and not contaminate it again, so it is important to take certain measures and precautions into account:

• Potable water should be stored in covered storage containers in cool, dark places.
• The potable water storage container should be equipped with a large lid for easy access and be cleaned between each fill cycle.
• It is important to note that the water can be contaminated again if elements or utensils are introduced to extract the potable water, therefore, it is recommended that the water be extracted through a manually operated valve system at the bottom of the container.
• People who manipulate the valve to extract potable water from the storage container should wash their hands beforehand to reduce the chances of contamination to others who will be drawing potable water.

Promoting the hygiene of users who use the potable water from the storage container is important, as the potable water will be lost if users handle the container with dirty and contaminated hands, teach them how to wash their hands properly, here is a post from: "How to wash your hands correctly and efficiently using soap?" and remove as many contaminants from your hands using soap.