Anaerobic Levels in your Rainwater Tank

Do you ever wonder why the water in your rainwater tank starts to smell, even if it looks clear and clean? Or might it have a slightly stale or funky taste?

Collecting more than rainwater

Storing water is more than connecting a pipe from your roof and filling up your water tanks when it rains next. Your water tanks collect more than just water; they also collect organic debris such as leaves, twigs, and bird and animal droppings.

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 tank water isn’t just water

It is made up of 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, but for millions of Australians, it’s a necessity. However, storing water for daily living requires regular maintenance and monitoring to ensure your household stays healthy.

Rainwater tanks collect water from roofs, bore and spear systems, dams, and creeks. But it’s not always just water that is harvested. Anything sitting on your roof or in the groundwater is washed into your water storage tanks.

Anaerobic conditions within your rainwater tank

Anaerobic conditions occur in your rainwater tanks when oxygen levels decrease. Oxygen is generally lower as the water gets deeper, especially when it is not being added with fresh water or a specific aeration system designed to add oxygen to the lower depths.

When animal faeces and organic matter are added to water, bacteria and other organisms are also naturally introduced. In warmer weather conditions, bacteria breed and help reduce the amount of oxygen in the water.

Anaerobic fermentation in your water tank

Stagnant water leads to “Anaerobic fermentation.” This natural process occurs when leaves and other organic materials decompose in the absence of oxygen. It releases thiols and hydrogen sulphide (the “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 the growth of microorganisms that produce sulphides, creating a distinctive sewage or rotten egg-like smell.

How to avoid this stagnant water scenario in your water tank

Pipework that does not entirely 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 odours, 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 tank sediments, anaerobic growth can occur, producing sulphides.

Your water tank 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 the catchment area and your tanks), try and divert or flush this through before the rain comes
• always clean overflowing pipes

Clean your water tank regularly

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 yearly or if you think the quality of your drinking water needs improving.

Removing and maintaining Anaerobic levels in your drinking water storage

Many taste and odour issues connected with tank water are caused when oxygen levels 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 to the bottom of your water tank and can be set to a timer to provide regular water circulation.

The AqueousAir™ is most suitable for water tanks whose floors have been cleaned of built-up sediment and where a filtration system is present between the tank and the house.

If your catchment area collects a lot of organic matter, such as leaves and twigs, and is not screened before the water enters the tank, then AqueousAir™ could potentially stir up organic sediment. Hence, regular cleaning and maintenance are recommended to maintain quality water.

Inspect your water tank(s) regularly

We recommend that you conduct six-monthly inspections of your tank and water quality. Your tanks should also be inspected every year for the presence of accumulated sediments. If sediment covers the bottom of the tank or is present in the water flow, the tank should be cleaned.

If your tank water turns rancid

Should your water turn rancid, our water technicians cannot save the contents of your water tanks. Still, they must dump the water, remove all sediment and organic material, and clean and sanitise the tank to ensure bacteria will not return once it 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.

If the stored water in your rainwater tanks remains unchecked and your water supply system is not maintained, your family’s health will be at risk.

If you suspect Anaerobic growth in your rainwater tanks, contact your local Pristine Water Systems water technician for a FREE inspection (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://www.health.gov.au/resources/publications/enhealth-guidance-guidance-on-the-use-of-rainwater-tanks

Source: https://rainharvesting.com.au/field-notes/articles/rain-harvesting/what-is-a-wet-rain-harvesting-system/