What is bacteriological contamination of water?

It is the contamination produced by potentially pathogenic germs. Bacteria are small living organisms, responsible for many of the diseases caused by water.

Although coliforms are harmless in principle, their presence in water indicates the possibility of contamination by germs. Consequently, water containing coliform bacteria is not “safe water” for drinking and cooking.

Total coliforms are common in the environment (soil) and in the intestines of animals. Faecal coliforms and  Escherichia Coli (E.Coli)  are found mainly in the faecal waste of animals. Faecal coliform contamination can come from nearby sewers, septic tanks, animal farms, nearby rodents, or poorly sealed wells. This contamination can be introduced into the well, or piping system during its construction or repair of a fault.

If you receive your drinking water directly from the tap and do not use storage tanks, you do not have to worry about this type of contamination. Public water supplies are normally treated with chlorine to disinfect and remove any possible microbiological contamination. Other possible disinfection systems can be:

  • Chloramine addition
  • Ultraviolet rays
  • Ozone

Check your water if you have any intestinal disorder, repetitive diarrhoea, vomiting, or abdominal cramps. Check with your local council or water supply company. Children and the elderly are more susceptible to coliform contamination. If necessary, rule out possible microbiological contamination by testing the drinking water.

If your water is from your own well, fountain or spring, or if you have storage tanks, frequent microbiological testing is advisable, as there is a high potential for coliform contamination. Even having installed a disinfection system, according to AquaDrink it is advisable to control possible bacteriological growth at least twice a year.

If your water is contaminated with some type of bacteria, that is, the result of the analysis classifies your water as “non-potable due to bacteriological contamination”:

  • Boil drinking and cooking water for at least 5 minutes, until you install a stable disinfection system that provides you with safe drinking water. You should also not brush your teeth with this water
  • Yes you can bathe, shower and wash clothes with this water
  • You can also use this water for irrigation (as long as sprinklers or micro-sprinklers are not used).

Systems for the treatment of water with microbiological contamination

Pathogenic germs can be eliminated by chemical or physical processes.

Chemical processes for water treatment

  • Chlorine disinfection
  • Disinfection by chlorine derivatives
  • Ozone disinfection

Physical processes for water treatment

  • Disinfection by UV LIGHT

Our recommendation for the elimination of germs in the water

If you consume water from a well with microbiological contamination for drinking and cooking, from our point of view the most accessible options for domestic use to make water drinkable are:

Disinfect with Chlorine

Chlorine is injected into the accumulation tank or into the delivery pipe to the storage or consumption tank. Chlorine dosing is done by installing a dosing pump. The dosed amount must be established by qualified personnel, according to the volume of water to be treated, the properties of the water according to the analysis carried out and the characteristics of the installation.

Careful maintenance of the dosing pump must be carried out, perhaps due to the action of the chlorine itself, the dosing membranes tend to crystallise, making it necessary to clean or replace them more or less frequently.

However,  chlorine is toxic and can generate other toxic compounds by binding to organic matter present in the water, which is why chlorination at home is a delicate process that, if you decide to do it, must be carried out very carefully and according to the indications of a person with experience and specialised in water treatment.

You should also be very careful when handling and storing chlorine, which should always be kept in a closed place with a door and key. Do not store liquid chlorine containers in places exposed to the sun or heat radiation.

If you have opted for chlorination as a disinfectant system, we advise you at the point of consumption for drinking and cooking, a cellulose filter to remove impurities, such as dead bacteria that tend to agglutinate, and a compacted carbon filter to remove chlorine residue and its secondary compounds (such as trihalomethanes).

Disinfect with UV Light

Ultraviolet radiation is a germicidal process that, with simple technology, without adding or removing anything from the water, manages to eliminate microbiological contamination.

Simply, the water is passed through a chamber where the lamp that emits ultraviolet light rays is located, producing the instant and safe destruction of all microorganisms, without altering the nature of the water, since it does not leave any type of residue.

Ultraviolet rays constitute one of the bands of the electromagnetic spectrum. Precisely, the strip that is between 10-400 nanometers, limiting with X-rays and the visible strip. The UV LIGHT attacks the nucleic acids of microorganisms, preventing their cell division, thus producing lethal effects for viruses, bacteria, spores and yeasts.

Advantages of UV LIGHT

  • Does not require contact time: the disinfection effect is immediate
  • Does not alter or modify the chemical composition of the water
  • Does not form harmful secondary compounds
  • Does not corrode installations
  • No handling risks
  • easy to install

To calculate the size and characteristics of the ultraviolet ray equipment, the following will be taken into account:

  • The flow of water to be treated
  • Existing microbiological contamination
  • The general characteristics of the water to be treated
  • Destination of the treated water
  • General characteristics of the transport facility

Our recommendation when treating microbiologically contaminated water will be, without a doubt, the use of germicidal lamps (UV light). The application of this type of disinfection is extensive and versatile, and you always get the advantage of not having to use chlorine or similar chemical substances.


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