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Zincalume and galvanised iron poisoning in tankwater

February 17, 2009

Hi all,

I have recently purchased a house, and, as usual got a house inspection by a qualified builder. The house passed ok, however the builder told me that my carport has Zincalume iron on the roof, whereas my house has Galvanised iron. Both of these roof's feed into a 4500L rainwater tank around the back of the house. He said that due to this, the full tank of water would be poisonous to drink and would kill my pets.

However, I have many friends who think they have the same iron on their roofs, and have been drinking water from their tanks for years without a problem. Does anyone know if my builder is correct? If it is, I would like to use the water up on my garden, which has fruit trees (namely orange, apple and lemon trees) so will this affect the fruit as well?

Thanks guys.

Darren Grose
House buyer - Swan Hill, Victoria, Australia

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Barring some unusual confounding problem, I do not think that you will have any problem. The only way to tell is to have a sample analyzed every couple of years to see if there are any changes with time and corrosion.
No two roofs are exactly the same, but if the neighbors have not died, you very probably will not.

James Watts
- Navarre, Florida
February 20, 2009

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Hi Darren,

As James says, no problem. The only aspect that needs watching with Zincalume and galvanised materials (and it doesn't apply in your case, by the sound of it) is that you shouldn't have water running from Zincalume onto galvanised - else the galvanised coating won't last as long as it should.

The water itself is fine.

Bill Reynolds [deceased]
consultant metallurgist - Ballarat, Victoria, Australia
We sadly relate the news that Bill passed away on Jan. 29, 2010.
February 23, 2009