Iron bacteria

Iron Bacteria in waterway If you have seen a reddish-brown sediment, stain or substance in your local waterway or stormwater drains, don’t be alarmed. The chances are that this is being caused by iron bacteria, which is a naturally occurring micro-organism.

Immediate impressions are that this reddish-brown sludge is something more sinister when found around sewerage pipes and the like. However, while it may be unsightly, there is no evidence to suggest that the bacteria are harmful to health.

Iron bacteria feed on iron and have been present in waterways for millions of years. When the bacteria are feeding, they leave slimy rust coloured deposits in the waterways. These deposits tend to be more noticeable during dry periods when the water is still and the deposits line the sides of creeks. However, heavy rainfall can wash these deposits from stormwater drains discolouring large volumes of water.

During the initial phases of iron bacteria activity, there may be a sewage smell and oily appearance on the surface of the water. This is merely attributed to the harmless chemical reaction taking place in the water.

Chemical process

Iron Bacteria reactionIron occurs naturally in the soil and leaches out continually into waterways. When oxygen, water and iron mix together they create the right conditions for iron bacteria to bloom.

Iron bacteria need to oxidise (change their chemical structure) to fulfil their energy requirements. This involves changing ferrous iron to ferric iron.

This process makes iron insoluble and produces the rust coloured slime deposits visible in waterways.

Reporting iron bacteria

It is important to remember there is no evidence that these iron bacteria are harmful to health or adversely affect our waterways. However, if you have spotted this condition in your area and would like it double checked, Council Officers are available to look into the problem.

For further information, contact Council.

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