Guarding Against E. coli: Essential Strategies for Ensuring Safe Water Tank Systems

Water tanks are an essential source of clean drinking water for many households across New Zealand. 

However, lurking within these tanks, there exists a hidden danger: Escherichia coli, or E. coli bacteria. 

Today we’ll look at how E. coli can find its way into your water tank, the potential risks it poses to your family’s health, and things you can do to prevent contamination.  

While the focus here is on E. coli, it should be noted that a range of harmful nasties, such as Cryptosporidium,  can enter water tanks by the same means.

How Does E. coli Get Into Your  Water Tank?

Animal and Bird Droppings: One of the main ways E. coli enters water tanks is through animal and bird droppings.

Whether it’s birds perched on roofs or animals traversing nearby areas, faecal matter can be washed into gutters and ultimately end up in water tanks during rainfall.

Roof Runoff: Rainwater runoff from roofs can carry various nasties, including dirt, debris, and organic matter, into water tanks. 

If the roof is contaminated with animal faeces or other sources of E. coli, the bacteria could be transported into the tank along with the runoff.

Contaminated Surfaces: Water tanks can also become contaminated if they are not properly sealed or maintained. 

Cracks, gaps or openings in tank lids or access points can allow E. coli from external sources to enter the tank, especially during heavy rainfall or flooding events.

Health Risks Associated with E. coli:

Gastrointestinal Illness (tummy trouble!): The presence of certain strains of E. coli in drinking water poses a significant risk of gastrointestinal illness, including diarrhoea, abdominal cramps, and nausea.

In severe cases, E. coli infection can lead to more serious complications such as kidney failure and hemolytic uremic syndrome (HUS), particularly in young children and the elderly.

Cross-Contamination: In addition to direct consumption, E. coli-contaminated water can lead to cross-contamination of food and surfaces, increasing the risk of foodborne illness. 

Proper hygiene practices, such as washing hands and disinfecting kitchen utensils, are essential to prevent the spread of E. coli and other harmful bacteria.

Preventing E. coli Contamination in Water Tanks – What You Can Do?:

Regular Maintenance: Routine inspection and maintenance of water tanks is crucial for minimising the risk of E. coli contamination. 

Prior to the tank this includes ensuring proper sealing of tank lids, repairing any cracks or openings, and cleaning gutters and roof surfaces to minimise the risk of faecal matter entering the tank.  

However, unfortunately nothing can stop all the bacteria entering the water tank and therefore regular water tank cleaning coupled with UV filtration is the only way to maintain safe water on an on-going basis.

Water Tank Cleaning: Regularly cleaning the water tank(s) to ensure any sediment build-up in which the bacteria can grow and multiply, is removed, and the water is purified, is essential.  

This minimises the risk of bacteria multiplying to even more dangerous levels and also allows a combination of sediment and UV filtration to work to its optimum as outlined below.

Filtration and Treatment: Installing sediment filters and a UV filtration system helps remove and/or neutralise bacteria, including E. coli, present in water tanks. 

The sediment filters typically have a minimum size of 1 micron – beyond this too much water pressure is lost.  E. coli and bacteria are typically narrower than 1 micron and therefore can pass through the sediment filters.  The UV light neutralises 99.9% of all bacteria.

It is important to note that the sediment levels in solution in the water need to be kept under control to allow the UV disinfection to operate fully.  Hence, a regular tank clean combined with UV filtration is recommended.  

An annual check and clean is optimal and from experience of cleaning thousands of tanks per annum, we strongly suggest never leaving a tank clean more than two years.

This combination of minimising the sediment that gets into water tanks by cleaning gutters and the roof as well as ensuring the water tank is airtight, along with a regular water tank clean and UV filtration can provide peace of mind and ensure the safety of the water supply.

E. coli contamination in water tanks poses a serious threat to public health, highlighting the importance of proper maintenance and sanitation practices. 

By understanding how E. coli can enter water tanks and implementing preventive measures, we can safeguard our water supply and protect the well-being of our communities. 

Regular inspection, tank cleaning and filtration are key components of a comprehensive approach to ensuring safe and clean drinking water for all.