boy drinking a glass of water

Tank Water Quality After Flooding – Is It Safe?

May 5, 2021

Have confidence in the quality of your water after heavy rainfall/ flooding.

Getting a lot of rain to fill your rainwater tanks seems like the ultimate water goal if you are a household that relies on it. Sounds good, but in reality a large downpour/flooding can cause your rainwater supply to become muddy and can create some unpleasant tastes and smells. 

When this occurs the best practice is to go back to the basics. Ensure your water supply is filtered sufficiently and perform thorough maintenance of your rainwater system.

Contaminants in Rainwater

Rainwater itself is extremely pure, however in the collection process it gets contaminated with airborne particles or anything on your roof, gutters, and the water tank itself. So the quality of your rainwater is greatly affected by the general surroundings, demographics, climate and of course, the rainwater collection system itself. 

Rainwater is also normally slightly acidic meaning that a lot of things it comes in contact with tend to travel on with it. And once the water is in the tank there is further opportunity for contamination which needs to be minimised. Thus it’s important to do everything you can to ensure your water is clean from the initial collection and storage, to when the water is consumed.

This is amplified with heavy rainfall and can very quickly affect the quality of your water. The main reason for this is even more leaves, vegetation, animal-borne contaminants and sediment is flushed down the gutters directly into the tank. This influx of water also stirs up sediment and contaminates at the bottom of the tank, ultimately pushing more of this through your pipes and the outlets in your home/facility. 

Monitoring and Maintenance

Monitoring and maintaining your rainwater system is essential in ensuring safe water for all uses around the home, most especially for drinking water. While preventative measures can be implemented during design and installation, it’s just as important to upkeep those measures. In the case of rainwater risk management, prevention is key to ensuring safe, high quality water. This section will help you determine and attend to any problematic issues that may impact your rainwater supply.


A. Trimming Trees/ Removing Vegetation

Keeping your roof catchment area clear of overhanging trees will help to prevent leaves and foliage collection. Cut back trees to remove dropping or dying leaves, and trim away branches that could be potential roosting points for birds or provide access for small animals and unwanted visitors.

B. Prevent Debris In Your Tank

Use leaf & rubbish diverters to protect inlets to rainwater tanks. Keep foliage and debris clear from your pipes to avoid clogging, blockages, rotting leaves and tannin leaching. To prevent entry of mosquitoes, insects and vermin, install a 1 mm mesh on inlet strainer and overflow. Finally, reduce the risk of flooding eaves by taking precautions to stop downpipe blockages and backflow.

C. Keeping Gutters Clean

Debris, leaves, moss and lichen should be kept clear from gutters. Gutter mesh is a simple way to avoid this and can be installed to keep vegetation and pests out. This can also reduce the risk of animal-borne contamination, leached tannins and sediment build up. Inspection and maintenance of roofing and gutters should occur every 6 months.

D. Keep Vermin and Pests Away

Take precautions to deter small animals and birds away from entering the tank. Ensure barriers such as mesh are installed to keep vermin out. Remove roosting places on your roof so that you don’t get too much bird poo. Keep in mind sometimes animals can be trapped and drown in tanks and can cause very high levels of contamination, so best to be vigilant.

E. Clean regularly

Examine tanks for accumulated sludge on the floor of the tank at least every 2 years. Sludge can be removed by completely emptying and rinsing the tank or via siphoning. There may even be tank cleaners who work in your area. Be aware that excessive sludge can harbour bacteria.

F. Regular Flushing with TankSafe™

Regular flushing of your water system will keep your tank and water line from any build-up of sediment, algae and unwanted elements. If you have a Hybrid UV system installed, we recommend dosing the system with TankSafe at least once a year. If no UV is installed, this should be done every 2 months, and after rain events.

G. Filter System Maintenance

Using a filtration system for your rainwater is a simple way to enjoy peace of mind. However, if you’re not changing your filters and lamps regularly they may not be doing their job effectively. Many filters have pores or media which trap or attract bacteria and contaminants. Once your filter is full of contaminants water will struggle to get through and what does may not be filtered effectively. If you are using an ultraviolet system, the lamp also needs to be replaced every 12 months to guarantee effectiveness. For more information contact our team for further assistance.

What sort of filter system is ideal for areas of flooding? 


In situations like these and for peace of mind all year round, the ideal filtration system is a Puretec Hybrid G13 Triple Filtration & UV All-in-one Unit. These systems are ideal as they kill 99.9% of bacteria, have two stages of sediment filtration for the muddiness and also feature a carbon block cartridge to reduce the taste and odours all those extra contaniates bring that have been flushed into your tank. 

In some situations where the contaminates and sediment are very high one of Puretec’s larger water treatment systems may be required to achieve the ideal results. 

There are also filtration solutions available for any issues with alternative water supplies such as bore and mains/town water.

For any further questions for your water filtration needs, give the North Coast Power & Water team a call on (02) 6651 4333 and we can advise you on the best water filtration solution for you. 

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