If you have any doubts about the safety of polyethylene water storage tanks, this article should dispel them. Poly water tanks are safe in every department and not harmful to your well-being. And no, they do NOT leach.
Polyethylene is inert
Polyethylene is inert, and unlike highly alkaline concrete tanks, poly tanks don't need to be flushed out with a full tank of water before you can use them. That single difference tells you most of what you need to know. A concrete tank has to be flushed because there is something in the material that would otherwise end up in your water. A poly tank does not, because there isn't. Inert means the material has nothing to give up and no interest in reacting with what it is holding. It sits there being a wall. Our piece on the truth about concrete tanks goes further into the comparison.
What Promax poly tanks are certified to
Promax poly tanks are made from polyethylene certified to AS/NZS 4020: 2002 Potable (Drinking) Water Standard & AS/NZS 2070: Part 1 and Part 8 Australian Standards for Food Contact. That's a technical way of saying that once the polyethylene is moulded into a tank, it can store potable water for human consumption. The water is not affected by heat, and ingress is impossible because the tanks are built to a standard with no allowance for cracking. Those are the certifications sitting behind the material, and they are the ones worth asking any tank manufacturer to name for you.
Why poly tanks do not leach
As for the issue of a poly tank leaching chemicals and other substances into the water, it just doesn't happen. As a chemically inactive material, food-grade polyethylene does not react with water. Leaching requires a reaction, or something soluble sitting in the material waiting to be dissolved out of it. Food-grade polyethylene offers neither. It is the same property that makes the material suitable for food contact in the first place, and it is why the question of what a poly tank might be adding to your stored water has a very short answer: nothing at all.
Why concrete tank water tastes different
In contrast, concrete tanks leach lime and calcium into the water, resulting in harder water. People who have used concrete tanks before switching to poly tanks will say the water tastes different and wrongly attribute this to polyethylene leaching. It is not the case. Instead, that "different taste" occurs because lime or calcium is no longer in their stored tank water. The change they notice is real, but they have the direction of it backwards. They are not tasting something the poly tank has added. They are noticing the absence of something the concrete tank had been adding all along, which is one of the sharper points in the concrete or plastic debate.
Every tank is virgin polyethylene
As a sustainable company, Promax applauds efforts to recycle and repurpose poly tanks at the end of their lives. However, old tanks are never re-made into new tanks. Every water tank is manufactured with 100% virgin polyethylene, yet another reason to be confident in the safety of poly tanks. Recycling has an obvious appeal and there are good uses for a poly tank once its working life is over. Feeding that material back into a new drinking water tank is not one of them, and it is not something Promax does. It is one of the reasons not all poly tanks are made equal.
First flush diversion
While poly tanks are perfectly safe, you can further enhance the water quality by using rainwater harvesting accessories. For example, a First Flush Downpipe Diverter kit can be likened to a purifier; it diverts the contaminated water that washes off your roof with the first few millimetres of rainfall. The result is much cleaner water going into the tank. Notice where the contamination in that sentence comes from. It is not the tank. It is the roof, the gutters, and whatever has settled on them since the last decent rain, and the first flush is when most of it travels.
Drawing the cleanest water from the tank
Inside your tank, a Floating Outtake floats on the water, drawing only the cleanest water from just below the surface. A tank is not uniformly clean from top to bottom. A fixed outlet takes whatever happens to be sitting at its level, which is not where the best water is. A floating outtake follows the surface down as the tank empties and keeps drawing from the same clean band no matter how full the tank is. It is a simple device that improves what comes out of the tap without changing anything about the tank itself, and it pairs well with the other steps in getting the cleanest water from your tank.
The short answer
A poly tank is a safe tank. In conjunction with accessories like First Flush Downpipe Diverters and Floating Outtakes, the water inside your storage tank will be clean and ready to drink. No chemicals, no concerns and no leaching. If you have any questions or concerns about the safety of your poly tank, give us a call and we'll ease your worries. Call Promax on 0800 77 66 29.