The easiest way to keep your tank clean is to keep the water clean. Any material in the water can taint the internal walls and floor of a storage tank, so when the question arises on how to clean your water tank, a common adage applies: prevention is better than the cure.
Stop debris at the downpipe
A Leaf Eater fits into the downpipe system and consists of two mesh screens that work together to stop debris and insects from entering the storage tank. A primary mesh screen is a barrier against larger items like leaves and branches, backed up by an insect-proof secondary screen made from finer mesh. The logic is simple: material that never enters the tank can never settle on the floor, taint the walls, or break down in the water. Filtration at the downpipe is also the easiest part of the system to inspect and clear, because it sits where you can reach it rather than inside a full tank. Devices like this sit in our rain harvesting accessories range.
Send the first flush to waste
A First Flush Diverter deals with what a screen cannot catch. It diverts dust and sediment that may settle on a roof when it starts to rain, leaving only clean water to flow into the tank. The first water off a roof carries whatever has built up there between showers, and it is the dirtiest water in any rainfall event. Sending it to waste costs a small amount of collected volume and removes much of the fine sediment that would otherwise sink to the tank floor. Between a Leaf Eater and a First Flush Diverter, a great deal of what would dirty a tank is dealt with before it ever arrives.
Keep the tank floor clear with a Tank Vac
If any debris gets into the tank, it settles on the floor where the outlet is located. The Tank Vac can keep this area clean by building up a head of pressure every time the tank fills to overflowing, then dumping out the overflow by sucking from the pipe across the tank's floor. Doing this removes any debris that might have settled there, leaving the fresh water that's just arrived in your tank. The useful part is that it works on its own: every overflow becomes a cleaning cycle, with nothing to switch on and no need to open the tank. There is more on this in our guide to getting the cleanest water from your rainwater tank.
Draw from the cleanest layer
A Floating Outtake floats on the surface and takes the cleanest water in your tank, about 100 – 150mm below the surface, no matter the water level. This matters because the two parts of a tank you would least like to draw from are the floor, where sediment settles, and the very top, where the surface film sits. A floating outtake sits in the band between the two and stays there as the level rises and falls through the season. Paired with a Tank Vac, one device keeps the floor clear while the other simply avoids it, which is why they are usually specified together rather than one or the other.
When cleaning is needed, and who should do it
With the cleanest possible water coming into your tank and internal devices like the Tank Vac and Floating Outtake working in harmony, the quality of your stored water is greatly enhanced. The better the water, the less likely your tank will need frequent cleaning. However, should you wish to clean the tank, there are a few ways to do it. By far the easiest is to hire a professional. There are a number of companies offering tank cleaning services around the country. As tanks become more common because of council regulations, you can also expect to see an increase in tank cleaning contractors, which should make one easier to find.
Cleaning a smaller tank yourself
If there are no professionals in your area, or if you prefer to save a few dollars and do it yourself, then a brush on top of a telescopic handle should allow you to scrub the walls and floor of a smaller tank. It is a good idea to clean your tank at the end of summer when water levels are low. Turn off the power if you have an electric pump and drain the water from your tank; use it to irrigate the garden so it doesn't go to waste. Run fresh water from your garden hose through the tank inlet to flush out any dirty water until the water coming from the outlet is clear. Once the tank is empty, reach through the access hole with a brush and scrub the walls and floor, rinsing as you go.
Working inside a large tank
Some larger capacity tanks, including large Promax ENDURO and XPRESS tanks, feature generously sized 600mm access holes, and you may feel like climbing into the tank to clean it. A word of caution: never do this alone. Always have someone with you when you work inside a tank, and ensure they have a spare ladder. That second person, and that spare ladder, are what get you out if something goes wrong. If you have any hesitation at all about climbing in, this is the point where hiring a contractor stops being a convenience and starts being the sensible call.
Why we don't recommend bleach
Avoid the use of chemicals like bleach. Some companies recommend a mixture of bleach and water for scrubbing the walls, but working with any chemicals in a confined space can be highly dangerous. Plus, if the tank water is used for drinking or cleaning, it is best to leave any bleach concoction out of the equation. The only liquid we'd recommend adding to your storage tank, besides water, is a product like TankSafe, manufactured by Puretec. This is a non-toxic, chlorine-free, tasteless and odourless rainwater tank purifier; it disinfects the water inside a tank and is a safe alternative to harmful chemicals.
The tank material itself
Modern poly tanks are made from high-quality materials. For example, Promax manufactures tanks using polyethylene certified to AS/NZS 4020: 2002 Potable (Drinking) Water Standard & AS/NZS 2070: Part 1 and Part 8 Australian Standards for Food Contact. Once moulded into a tank, the water is safe for human consumption. Keeping that water clean and fresh will go a long way to maintaining that quality, and as we've already said, think prevention instead of cure. If you want the detail on the material itself, we cover it in are poly water tanks safe. By maximising the purity of the water coming into the tank and while it is stored inside, you'll soon learn that the cleaner the water, the cleaner the tank.