If you live in a remote area without a connection to the mains water supply, you will rely on a rainwater tank to provide you with clean water for use in your household.  In a climate where rainfall is relatively low, the cleanliness and usability of your stored rainwater is very important, and an outbreak of algae in your tank can spell real trouble. 

Algae are simple plants that live in water.  Unfortunately, some species of algae carry bacteria that produce potentially harmful toxins, which can render your water unfit for consumption by both people and animals.

Here are a few simple and practical tips on how to keep your rainwater tank an algae-free zone.

Choose the right rainwater storage tank

Like most plants, algae uses sunlight to photosynthesise, creating the nutrients it needs to proliferate and grow.  Therefore, it follows that choosing a water tank that does not allow light through its walls will prevent the growth of algae.  To check this, look down into the tank from the top; you'll immediately be able to see if any light is penetrating the tank walls.

Add bleach to your stored water

Algae cannot survive in water that has been treated with bleach, and simple household bleach is all you need for this cure.  Simply add a quarter of a teaspoon of bleach to every 4.5 litres of stored water and your water will stay algae-free.

Add chlorine to your stored water

Algae are also killed by chlorine, and the addition of four parts chlorine to every 1,000,000 parts of water will see-off any potential algal growth.  Water is still safe to drink and to use for irrigation purposes when it has been treated with such a low proportion of chlorine.

Note:  Don't use both chlorine and bleach; choose one or the other and stick to it!  If you don't do so already, it's a good idea to put your drinking water through a water filter before you drink it.  This will get rid of any lingering traces of chemicals that could leave your water tasting 'metallic' and unpleasant.

In conclusion

You can ensure that your rainwater tank stays algae-free and your water is safe to use by following the tips given above.  If you are concerned that your old rainwater tank is encouraging the growth of algae, take a trip to your local agricultural equipment supplies store for more information on opaque rainwater tanks and other proprietary algae treatments.