Blog    |    How to Clean and Prevent Algae Growth in Your Water Tank

Cleaning Water Tank - GoToTanks

If you’re in the market for water storage tank or already have one, you’ll quickly find out that there’s a bit of maintenance involved to keep your water as pristine as possible – at least if you’re buying a white or translucent tank. These white tanks are typically used for chemicals, food syrups, and fuel. While they can be used for storing water, it’s typical for indoor use.

When white tanks are exposed to the sunlight, inevitably it will become a spawning ground for bacteria and algae which can cause a bitter taste, odor, and risking health factors of stagnant water. This article will talk about how to maintain your water storage tank, how often it needs to be done, and a step-by-step direction on how to clean it.

When Do I Need to Clean my Water Storage Tank?

There are certain events with your water storage tank that will need to be cleaned and disinfected:

After construction of a new water supply

When you’re done making repairs to an existing water supply

After a water system has been unused for several months

When the results of a coliform bacteria test indicate contamination

Sometimes disinfection will give relief from iron bacteria and from sulfide odors caused by sulfate-reducing bacteria often associated with iron bacteria

How Often Do I Need to Clean My Water Storage Tank?

As with any water storage tank underground or out of direct and indirect sunlight, the timeframe is typically a year. This is due to brown algae, slime, and sediment build-up slowly growing in the tank. If a water storage tank is getting indirect sunlight, it may be recommended to clean every three to six months whereas direct sunlight that penetrates into the tank will have to cleaned out regularly due to algae growth.

Steps On Cleaning Your Water Storage Tanks

Caution: You will be using bleach to clean the storage tank and getting into confined spaces with chlorine can cause breathing problems and health risks. Don’t get inside a water storage tank unless you have the proper training and equipment.

Cleaning your water storage tank will be an all day event. Typically, this can even stretch into the next day. You will need to coordinate with your water delivery and sewage collection service when you disinfect and refill your tank. Before you get started, here are a few things you will need to expedite the cleaning process:

Floor Mop with adjustable rod and sponge head


Pressure washer (recommended, but optional)

Shop vac or wet/dry vacuum

Sump pump (optional)

Unscented liquid bleach without fiber guard

Disposable gloves

Eye protection

Drain the Tank

Drain your water storage tank by either by running the system or using a submersible sump pump to empty it out. You want to get the water as low as possible so you have access to all sides and even bottom of the storage tank for cleaning.


After draining your water storage tank, make the disinfectant mixture. In a bucket, use one part bleach with four parts hot water. This will kill bacteria, algae, and organic material that could possibly serve as food for bacteria.

Scrub a Dub Dub

Use your mop (with adjustable handle) to dip into the bleach and scrub the sides and bottom of your tank. If you opted in using a pressure washer, a light scrub with the mop will suffice. Once done pre-scrubbing with the mop, you can now use the pressure washer to spray all the nooks of the inside. Wear a mask and eye protection, as bleach can get inside your lungs and burn the eyes.

Drain Again

After scrubbing all corners of your water storage tank, there of course will be a build up of dirty water and bleach at the bottom which needs to be extracted before the disinfection phase can commence. Using your shop vac or sump pump, extract the remaining water from the storage tank. You can dump the remaining mixed bleach into the tank after extracting to get as much of the dirty water out.

Your Tank is Now Clean

Congratulations, your water storage tank is now clean. The next step is to disinfect your water storage tank and piping system. This will take at least four to 24 hours to disinfect all pipes and the water storage tank as well.

Disinfecting Your Water Storage Tank and System

Now that your water storage tank is clean, it’s time to disinfect the rest of the system as well as thoroughly disinfect your tank.

Fill The Tank

With coordinating with your water service delivery, fill up your water storage tank and add a mixture of five liters of bleach for every 1,000 liters of water being filled.

Fill the System & Wait

When your storage tank has been filled up, turn on all the faucets that your water storage tank uses. Leave them on till you can smell the bleach coming from the faucet, then turn them off. The whole system disinfects after approximately 24 hours.

Flush the System & Refill

Flush the system of the disinfectant after the appropriate amount of time. Open up all your faucets and empty out your water storage tank. Once that is empty, you can now have your water service delivery truck fill it up the tank once more to finally have clean, pure water. Turn on all the taps till you can’t smell bleach within the water.

Want to Avoid All This Trouble?

Instead of using a white or translucent water tank outdoor, buy a dark colored tank that inhibits algae growth by blocking sunlight from coming in. You won’t have to waste your weekend going through this lengthy and laborious process. Go To Tanks is the #1 storage tank supplier in the nation for water storage needs and we have a wide selection of dark colored tanks for you to choose from. Call today at 1-877-468-2657 and we’ll help you put your algae scrubbing days behind you.

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