It is well known that plastic has caused health problems in the past.

Below is a list of possible health problems that can result from human over-exposure to the chemicals used in various types of plastics.

• asthma
• birth defects
• cancer
• chronic bronchitis
• deafness
• diabetes
• genetic changes
• hyperactivity
• indigestion
• infertility
• liver dysfunction
• obesity
• skin diseases
• skin rashes
• ulcers
• vision failure

Many rainwater harvesting tanks are made of Polyethylene. Polyethylene & HD Polyethylene (PET, HDPE) are considered safe to use in normal conditions. HD Polyethylene #2 is the more durable of the two. However these plastics may leach when exposed to UV, heat and over time from natural breakdown. The FDA deems this plastic to be safe but you should err on the side of safety as leaching will intensify over time - if bottles are made of polyethylene, they are considered as a ONE USE ONLY bottle!

If you intend your rainwater harvester to provide drinking water for livestock then think carefully about which type of tank you buy. Fibreglass rain water tanks do not leach out.

Copper poisoning linked to plastic water tanks

New research from Australia, where rainwater harvesting is very established, has revealed dangers related to plastic water storage tanks.

A recent case of copper poisoning is said to be caused by acidic rainwater from plastic tanks corroding copper water pipes. There is nothing wrong with the water, however rainwater collected in plastic and plastic lined water tanks is acidic and can react with the copper pipes that carry the water to your household taps. Dissolved copper in drinking water causes gastric problems and headaches, and in severe cases cirrhosis of the liver.

We do not use rainwater for drinking in the UK, but care must be taken when using it for watering livestock, especially sheep to whom copper is especially toxic.

Bega Valley Shire Council's Environmental Health Coordinator, Greg O'Donnell advises that "If you have a plastic or plastic lined rainwater tank and also have copper plumbing pipes or fittings in your home, there is a risk that you may have elevated copper levels in your water supply."

The problem occurs when rainwater from plastic or plastic lined tanks sits for long periods in the copper pipes in the plumbing system.

In that time the acidic rainwater can corrode the copper pipe and cause copper to leach into the water supply in the pipes.

So the problem is worst after rainwater has been sitting in the copper pipes for a long time.

It is advised that you flush the pipes before using any of the water, and this can be done by running a tap for 30 seconds or more, depending on the length of the copper piping in the system, or, simply, DON'T use plastic storage tanks!

(courtesy of ABC South East NSW)