Thread: Rainwater tanks - Plastic vs Galv

As Silent says very few gal tanks made these days for a couple of reasons. BlueScope (Previously BHP Sheet and Coil) mostly supply aquaplate which is galvanised or Zincalume steel with a food grade vinyl bonded to the interior of the tank steel.

All the tanks are usually made with a rivet system and sealed with silicone.

The other reason gal tanks aren't used much now for household water is because they used to be sealed with solder and lead based solder is banned in any type of plumbing for household use.

The reason gal tanks don't last long and end up with early perforation is from a couple of factors.

All gal tanks used to be supplied with sacrificial anodes to be suspended in the tank. They seemed to go the way of buttoned up boots or people forgot to replace them when they disintegrated.

Another factor was that with advent of copper plumbing people ran the copper right up to the tank and then you got electrolysis on the tank from the copper. BHP brought out a Technical Bulletin noting that no copper should be within 3 metres of a gal tank.

And another reason was the advent of Tile, Zincalume and Colorbond roofs in the country as the water off a Tile, Zincalume or Colorbond is pure water with no protective salts in the water and this causes the gal coating to be removed from the steel tank.

BHP tried to overcome this by trying to get the tank makers to use Zincalume and seal the tank with silicone. This was like beating your head against the wall all you got was a headache from the tankmakers.

The next move was to Aquaplate and then the government stepped in with a ban on lead solder and it all became a whole new paradigm.

As to a steel tank sitting on the ground the usually make an earth ring slightly bigger than the diameter of the tank. This is made level sitting on the ground and filled with sand. The bottom of the tank is made from double sided Aquaplate and the earth ring has aquaplate on the inside of it and this protects the steel from the wet sand.

How do I know all this. 11 years with Lysaghts trying to educate tankmakers on Zincalume and Aquaplate

Just my 2 cents worth of useless information.

Originally Posted by Felder

Nope.


And Nope.

Thanks Brenden, always wondered about that.

11 years with Lysaghts trying to educate tankmakers on Zincalume and Aquaplate

We used to make Gal tanks back in the 80's. We bought steel from Lysaghts all the time and one of your colleagues probably tried to talk my old man into using Zincalume. I also remember when Aquaplate came out but it was right near the end, so never got to use it.

I soldered plenty of gal tanks in my time. The rings were riveted first with cold rivets - a two man job. The old man was taught how to do it when he was an apprentice in the early 60's and he never changed his technique.

My brother in law uses tek screws and this grey goop that comes out of a cartridge. The old man rolls his eyes every time he sees one of the BIL's tanks. "Old Tuckey would roll in his grave" - Tuckey was his boss as an apprentice.

We made a tank out of colorbond roofing offcuts in 1986. It was still holding water but leaking from pinholes when we sold the house last year.

40 years ago when we bought our farm the house had a 2000 gal tank on the block laundry roof the frogs would live within the blocks then up and into the tank and drown.

It was mid summer and my job was to get into the tank and scoop out the 1 foot deep mush of rotting frogs. To say it was the most unpleasant sauna I have ever had would be an understatement. I do remember the smell lingered with me for weeks.

We put in a bore that went a few hundred feet down into sandstone and brought up the purest water - we then got a 20 000 gal concrete tank and life was grand for decades after that.

I saw on the idjut box a few weeks back that some crew in Brisvegas are making corro tanks from stainless steel sheet. Something like a 40yr warranty. I don't know the joining or sealing technique used, but prolly the usual rivets, and s/s can be soldered. Would be a lovely tank if you could afford it .

Cheers