How to Clean and Disinfect a Drinking Water Tank or Reservoir?

This post is also available in: Spanish French

If you have a drinking water tank or reservoir in your home or business, it’s essential to clean it regularly to ensure the quality of the water you store and avoid health risks.

Gimasur, experts in water tank cleaning, explains step by step how to do it, as well as the key regulations and recommendations you should follow.

How to Clean a Drinking Water Tank

Emptying the Tank

To begin cleaning, completely empty the tank. You can use a submersible pump to facilitate drainage if you don’t have a drain.

Clean the Walls and Bottom

Use pressurized water, a stiff-bristled brush, and a descaling agent to clean the walls and bottom of the tank or reservoir. This will help remove biofilm, limescale and incrustations, accumulated sediments, and any organic residue that may be present.

Disinfecting the Tank

Once the tank is clean, disinfect it with a chlorine solution suitable for drinking water. Sodium hypochlorite for drinking water is one of the best disinfectants. The exact dose should follow the product instructions to ensure proper disinfection. For example, if a hyperchlorination of 20 mg/l of free residual chlorine is achieved, it should be left to act for a minimum time of 15 minutes.

After applying the disinfectant and allowing it to act, rinse several times with clean pressurized water to remove any residue of chemical products and remaining dirt. This step is crucial to ensure that the water is not contaminated again.

Refilling the Tank

Once rinsed, refill the tank with drinking water. It is recommended to perform a potability analysis of the water 15 days after cleaning to ensure it is free of contaminants.

You should repeat this cleaning and disinfection process at least once a year, although the frequency may vary depending on the size of the tank, usage, and environmental conditions. The best time of year to do it is in winter or spring.

Consequences of Having a Poorly Maintained Tank

Inadequate cleaning of the tank or reservoir can lead to the proliferation of dangerous bacteria, such as Legionella, mesophilic aerobes, Clostridium perfringens, and even E. Coli, fecal coliforms, and intestinal enterococci, which contaminate the water and put the health of those who consume it at risk. Additionally, sediments and residues can obstruct the distribution system and generate bad odors and tastes in the water.

More Recommendations on How to Clean a Water Tank

Safety During Cleaning:

At Gimasur, we recommend first requesting the Safety Data Sheet (SDS) of the products you will use, as some of them can create dangerous chemical reactions. Always use personal protective equipment (PPE), such as gloves, protective goggles, and masks, to avoid contact with chemicals or their vapors. It is also important to adequately ventilate the space during the process.

Proper Sealing of the Tank:

Make sure the tank is well-sealed to prevent the entry of animals, insects, or debris that could contaminate the water. Gimasur specializes in the inspection and maintenance of water tanks to ensure their optimal functioning.

Taking a Drinking Water Tank Out of Service:

If you only use the water during specific periods such as summer, make sure you don’t leave stagnant water after use. You should completely empty the drinking water tank or reservoir, as well as hot water heaters and accumulators. Emptying doesn’t mean wasting water; you can cut off its filling a few days in advance so that the water is used up gradually. Stagnant water is the main reason why dangerous bacteria proliferate. If bacterial or algae growth is observed, this is a good time to carry out the cleaning and disinfection of the tank.

Protect the Drinking Water Tank:

Direct sunlight increases water temperature, evaporates chlorine, and allows algae or green slime growth. As much as possible, any water tank should be protected either with a built structure or a roof. This will significantly help maintain water quality.

Cleaning Frequency

Regulations state that tank cleaning must be carried out at least once a year, although in cases of higher usage or adverse environmental conditions, it may be necessary to reduce this frequency or even increase it for very large tanks.

However, if you don’t have the necessary means or need an expert professional to carry it out, at Gimasur we offer annual cleaning and disinfection services for your tank or cistern.

Regulations for cleaning cisterns and tanks in Spain

In Spain, cistern cleaning is regulated by Royal Decree 3/2023, which establishes the health criteria for the quality of water for human consumption. According to these regulations, cisterns storing drinking water must be cleaned and disinfected regularly, and must be inspected by specialized technicians.

There is also another regulation that governs the cleaning and disinfection of drinking water tanks, Royal Decree 487/2022, which aims to prevent and control legionellosis, a bacteria that proliferates in water.

It is the responsibility of the owner or supply manager of the cistern to ensure that all regulations are met, maintain a maintenance plan, and keep records of the cleanings and disinfections carried out.

Trust Gimasur for the cleaning and disinfection of your cistern or tank

At Gimasur, we are experts in cleaning and disinfecting cisterns and drinking water tanks. Our highly qualified team follows the most rigorous procedures and current regulations to ensure water quality and prevent the proliferation of bacteria such as Legionella.

After each cleaning and disinfection, Gimasur issues an official health Certificate, and after 15 days, we can carry out a confirmation of its correct disinfection through a microbiological analysis in an accredited Laboratory.

We offer advice on the installation and maintenance of a chlorine dosing system so that the stored water remains potable throughout the year.

If you’re looking for a reliable service for cleaning, disinfecting, and maintaining your cistern or drinking water tank, Gimasur is the solution.

Contact us for more information at phone: 📞+34 958 07 4444 or 📞+34 622 951 855