Ever wondered why the water in your rainwater tanks starts to smell, even if the water looks clear and clean? Or might have a slight stale or funky taste?
Storing water is more than just connecting a pipe from your roof and filling up your water tanks when it next rains. Your water tanks are collecting more than just water, they are collecting organic debris such as leaves and twigs, bird and animal droppings, and for those extended periods when it doesn’t rain, you are the local watering hole for insects, reptiles and anything else that can get access to your precious commodity.
Your water isn’t just water. It is layers of varying amounts of oxygen, a breeding ground for bacteria, and a death trap for insects and animals.
It might seem like a simple task, and for millions of Australians, it’s a necessity. But storing water for day to day living requires regular maintenance and monitoring to ensure you and your household stay healthy.
Rainwater tanks collect water from roof, bore and spear systems, dams and creeks. But it’s not always just water that is harvested. Anything that is sitting on your roof or in the ground water, is washed into your water storage tanks.
Sediment builds up over time. This ‘sludge’ is the perfect breeding ground for bacteria and water viruses.
As depicted in this cutaway image of a rainwater tank, your water storage has multiple layers that have varying degrees of usability:
- Top layer: most amount of oxygen, but is where insect larvae and algae can be found
- Middle layer: Most usable water. Oxygen levels start to decrease
- Lower layer: Where organic material builds up, and this is where bacteria breeds. Oxygen levels are thinner as this is the Anaerobic level.
Anaerobic conditions occur in your rainwater tanks when oxygen levels decrease. Oxygen is generally lower the deeper the water gets, especially when it is not being added with fresh water or a specific aeration pump designed to add oxygen to the lower depths. When animal faeces and organic matter are added to water, bacteria and other organisms also are naturally introduced. In warmer weather conditions, bacteria breeds, and helps to reduce the amount of oxygen in the water.
Stagnant water leads to “Anaerobic fermentation”. This is a natural process that occurs when leaves and other organic materials decompose in the absence of oxygen. This process releases thiols and hydrogen sulphide (“rotten egg” smell).
Sediment can accumulate in the bottom of your tanks when they are not cleaned frequently. In warm to hot weather, anaerobic conditions develop, leading to growth of microorganisms that produce sulfides, creating the distinctive sewage or rotten egg-like smell.
How can we avoid this stagnant water scenario?
Pipework that does not completely self-drain (for example, u-bends or underground piping from roof catchments to tanks, between tanks or from tanks to buildings) can also be a source of off-tastes and odors, particularly where stagnant water can develop and be retained between rain events. In these environments, slimes and biofilms can be formed and in the same manner as for tank sediments, anaerobic growth can occur, leading to production of sulfides.
The solution? Here are a few simple maintenance tips to help keep your water pristine;
- regularly clean out First Flush Systems (if you have one)
- always check for debris from roofs and gutters, and clear when necessary
- if you have a wet system (water lying dormant underground between catchment area you’re your tanks), try and divert or flush this through before the rain comes
- always clean overflowing pipes
Anaerobic growth in accumulated sediment at the bottom of your tanks can be prevented by cleaning your tanks regularly to remove the accumulated sediment. You can do this by monitoring your water tanks on a yearly basis, or if you think there’s something wrong with the quality of your drinking water.
Removing and maintaining Anaerobic levels in your drinking water storage
Many of the taste and odor issues connected with tank water are caused when oxygen levels in the water become low, and anaerobic processes develop. Stagnant water can be rejuvenated and restored to drinking quality. At Pristine Water Systems, our water technicians will:
- Remove sediment from the base of the water tank, while they are full, with minimal water loss.
- If required, filter the water to remove any floating debris
- Introduce our AqueousPro™ water sanitizer to kill bacteria and water viruses. This process also helps introduce oxygen
- Circulate the water, mixing in the water sanitizer and ensuring the water is completely oxygenated in all depths
- Finally, we conduct water tests to ensure your water meets our standards.
Pristine Water Systems also supplies the AqueousAir™ oxygenation system. This unique system introduces oxygen through to the bottom of your water tank and can be set to a timer to provide a regular circulation of water.
The AqueousAir™ is most suitable for water tanks that have had the floor cleaned of built up sediment, and where a filtration system is present between tank and house. If your catchment area collects a high amount of organic matter such as leaves and twigs, and is not screened before water enters the tank, then using the AqueousAir™ could potentially stir up organic sediment in your tank. Hence, regular cleaning and maintenance is recommended to maintain quality water.
We recommend that you conduct 6-monthly inspections of your tank and water quality. Every 1-2 years your tanks should be inspected for the presence of accumulated sediments. If the bottom of the tank is covered with sediment or if sediment is present in the water flow, the tank should be cleaned.
Should your water turn Rancid, our water technicians cannot save the contents of your water tanks, but will need to dump the water, remove all sediment and organic material, and clean and sanitise the tank to ensure bacteria will not return once the tank is refilled.
Rancid water is typically caused by animals or reptiles getting trapped in your water tanks. It is a common problem that we deal with, and once the carcass starts to decompose, this requires a complete overhaul of your tank and water supply system.
The health of your family will be at risk if the stored water in your rainwater tanks remains unchecked and your water supply system not maintained.
If you suspect there’s an Anaerobic growth in your rainwater tanks, contact your local Pristine Water Systems water technician for a FREE inspection of your rainwater tanks (conditions apply).
Don’t you and your loved ones deserve PRISTINE water?
Source: Extracts from Australian Department of Health “Guidance on use of Rainwater Tanks: https://www1.health.gov.au/internet/main/publishing.nsf/Content/0D71DB86E9DA7CF1CA257BF0001CBF2F/$File/enhealth-raintank.pdf