Advise on plumbing downpipes to drinking water tank

If I was you, I would also give careful consideration to providing some means of accessing the underground section of your system to enable flushing/cleaning.

Being the lowest point in the system it will collect fine silt and possibly other debris. This will happen even if you have a fairly efficient 'first flush' system. The velocity of water being pushed through that low spot will be pretty slow, allowing a lot of the debris to drop out and settle, thereby reducing the capacity of your pipe.

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Originally Posted by HangOver

New house and need to plumb my house down pipes to a water tank for drinking water. The down pipes appear to be 100mm PVC, (I havent measured) and already fitted to the house.

Advise needed how to go about it. I want the down pipes connected to underground pipes then to the water tank, about 8m from the house.

If the downpipes are 100mm, should the underground pipe be 100mm also or bigger?
Is standard PVC pipe OK or do I need something heavier.
Some of the underground pipe will need to be driven over, I was thinking about 500mm deep, will this be OK?
Best first rain diverter option?
I am guessing any joints need gluing together, best stuff to use?

Best place to buy this stuff around perth?

Any other hints or tips welcome

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Hi there.
I will be going through this task just south of Bunbury in a few months when our new house is finished.

I have previously worked out that two 90mm dia PVC pipes would be sufficient to drain about a 400sq.m roof, it will be a charged system like yours. I was told to try to get at least 1m fall from the gutters to top of tank so you have sufficient head to "push" the water through the charged system.

It is a must to set up a drain/flush point at a low point in the pipe(s). It is common down here to leave the drain cap off during the summer months and wait for the first 30mm or so of winter rain before capping it, to flush off the roof.

Have fun.
Cheers,
Chris

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Originally Posted by Gary S11

Hi, you only need 90mm storm water pipe ,a lot cheaper, If your running the pipe trough the air to the tank no probs, if your going under ground from down pipe to tank you will need a flush tee at the lowest point as stuff 'will" get on there. also the bottom of your gutter has to be 200 mm higher min than your tank as the water wont transfer other wise
the rest is pretty much covered ..Gary

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Me personaly, I would not use 90mm for uderground especially where cars will be driven over it. The reason it is cheaper than 100mm is it is much thinner.

Not sure if it has improved but many years ago 90mm was not very well UV stabilized, and if in a sunny spot would get brittle. We overcame this by painting.

Dave.