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Water tanks are used both in industry and in private households to store liquids and trickling substances. Depending on their capacity, larger tanks are used in the garden to collect rainwater or fresh water, while smaller tanks are widely used in caravans when travelling or camping. Regardless of how many litres of water a tank can hold or what it is used for, all tanks have one thing in common: they need to be cleaned regularly. Read this guide to find out why this is important and how to do it.

Why cleaning water tanks is important

Whether you want to know how to clean a household cistern or are interested in what industrial tank cleaning entails, here’s some good news: water tanks are generally low maintenance and easy to clean. However, to ensure that they can be used in the long term and fulfil all hygiene and cleanliness requirements, they must be cleaned properly. Water tank cleaning is essential for the following reasons:

  • Changing tank contents: if you want to use the tank for a different substance than before, all residues from the previous filling must be removed. If you do not do this, there is a risk that the new contents will be contaminated or the substances may even react with each other and, in the worst case, pose a safety risk.
  • Removing dirt, germs, and algae in the water tank: Even if you only fill your tank with water, particles will accumulate after a while and germs can form. A well-known example of this is biofilm. If the water remains in the tank for a long time, algae, bacteria or even microorganisms can spread.
  • Reconditioning of industrially used tanks: Discarded IBC containers that no longer fulfil the high hygiene standards of the food or pharmaceutical industry can still be used by other production companies or in the private sector as water tanks (for rainwater or service water, for example). This changes the intended use of the tank: It is now considered “reconditioned.” Before the used tanks can be sold at a favourable price, they must be thoroughly cleaned inside and out, and the previous filling must be indicated.

How often you decide to clean a water tank should depend initially on the contents. A conventional water tank should be thoroughly cleaned twice a year to prevent contamination of the water and the formation of biofilm. If you use the tank for chemicals or foodstuffs, the interval depends on the recommendations for the respective contents or the applicable industry guidelines.

Water tank cleaning – do it yourself or hire an expert?

If you want to know how to clean your water tank at home easily then you’re in the right place. But if you’d rather hand off the task, there are companies that specialise in everything from rainwater tank cleaning to water tank treatment. Consider the following factors before you decide:

  • Is the tank commercially or privately used?
  • What are the contents of the tank? 
  • How heavily soiled is the tank?

Regular cistern cleaning at home can be done quickly, but the challenge is greater for tanks used in the food or pharmaceutical industry. Here, particularly high demands are placed on hygiene and cleanliness and various legal regulations may have to be observed, such as proper handling of hazardous substances, the protection and management of water resources in accordance with the Water Resources Act 1991, and overall food safety or occupational health and safety requirements. In these circumstances, it is easier to leave your IBC container cleaning to the professionals. However, you can generally do it yourself with the right equipment and cleaning agents, as long as you are careful.

Only clean IBC containers that contain chemicals on surfaces that comply with the relevant safety regulations. As a rule, an asphalted surface with separate wastewater access is required to prevent chemical residues from seeping into the groundwater.

How to clean a water tank

Whether at home or at work: We have compiled the best water tank cleaning tips for you.

  1. Empty the container and unscrew the fitting

    To clean the tank thoroughly, you must first remove its entire contents. The best way to do this is to unscrew the outlet tap. This makes it easier to drain and clean the tank and is necessary later anyway to thoroughly remove any residue from the fittings.

  2. Clean the outside of the water tank

    First, you should thoroughly rinse the outside of the water tank so that no new dirt gets inside during the subsequent internal cleaning. No special cleaning agent is required to clean the outside of the tank. Water, a sponge or brush and a standard household cleaner are sufficient to remove external dirt. If you want to do it as quickly as possible, use a pressure washer.

  3. Clean the inside of the water tank

    For this step, you will need a pressure washer, cleaning agent and water. What you use to clean with depends on what you have previously stored in the tank. For household cistern cleaning, use cleaning agents that are specifically effective against algae or bacteria. Important: Algae should always be removed completely. You can clean the water tank with citric acid, which is particularly environmentally friendly. For industrial tank cleaning, acid or alkali-based agents are often used, e.g. chlorine-based cleaners, depending on the chemical properties of the previous tank contents.
    To clean the inside of the water tank, mix the cleaning agent with water in the ratio recommended by the manufacturer and pour it into the tank of the pressure washer. Then thoroughly spray the inside walls with the cleaning solution through the filler opening of the container. Finally, rinse generously with clear water until there are no more residues of the cleaner.

  4. Clean the container fittings

    To ensure that the contents of the tank are not contaminated during removal, it is important to clean the outlet tap and the corresponding seal particularly thoroughly. If in doubt, simply replace them. Use the same cleaning agent for this as for cleaning the inside. Use specially shaped brushes to reach nooks and crannies that are difficult to access. Finally, rinse everything out with clear water and screw the fittings back onto the tank. Check that the seals are not damaged and that the filler and outlet openings close securely.

Chemicals aren’t always necessary: Cleaning water tanks in an environmentally friendly way can be done using citric acid. Other household remedies such as vinegar or baking soda are also suitable for completely removing limescale, deposits or algae. If you’re interested in how to clean IBC tanks for drinking water, these home remedies are particularly suitable. However, if the tank was filled with substances other than water, you should use acid or alkaline cleaners.

FAQ for water tank cleaning

Why do I need to clean a water tank?

If the container is used in the food or chemical industry, it must comply with strict hygiene regulations to ensure that the products are safe. Therefore, any form of contamination must be excluded. When tanks are used for water storage, deposits or even a biofilm of algae and microorganisms can form in the stagnant water over time, which can impair the water quality and pose a health risk. You should always remove algae in the water tank!

What is the best way to clean my water tank?

Use a pressure washer to clean the tank quickly and thoroughly. Fill the tank with a mixture of water and the appropriate cleaning agent and spray the inside and outside walls, as well as all openings thoroughly. The high pressure provides a mechanical cleaning effect.

Which cleaning agent should I use?

The cleaning agent you use depends on the contents of the tank. For water tanks, use a cleaner that dissolves algae and germs and prevents them from forming again. Cleaning with citric acid is particularly environmentally friendly and suitable for freshwater tanks, as it is completely biodegradable. If you’re cleaning a water tank that stored chemicals or hazardous substances, on the other hand, special cleaning agents that are adapted to the chemical properties of the previous contents are required. Ask your specialist retailer for suitable agents.

How often do I need to clean a water tank?

Every time you want to replace the contents, you must also clean the water tank. However, even if the tank is filled with the same amount of water, it is advisable to clean it at least twice a year to prevent the buildup of biofilm.

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© – Danishkhan