Concrete slab for water tank

[tourgy]

Hi everyone,
I have purchased a 4500 litre plastic water tank that will be delivered early April. Got a good deal so it was too good to refuse

The people I purchased it from recommend putting it on a bed of riversand.
I want to put it a bit higher and when I told then I was thinking about putting it on house bricks the did not recommend that as some of the bricks may crack.

My other option is a concrete slab which I am awaiting a second quote for (the first quote was very high and scared me). 2 metred squared at $700.

Another option I was thinking of was the thick concrete square pavers you see around the place and doubling them up so there is a bit of clearance for the bottom of the tank.

What is the general consensus on these? Will they be ok to hold the weight without a problem or should I get a slab layed down?

Oh and please do not recommend I do the work myself as I have stated in earlier posts I am hopeless when it comes to doing this sort of stuff .

Not good I know. But at least I can make excellent beer. So I reckon that counts for something.

cheers
tourgy

[floobyduster]

Hi tourgy

If you make great beer and have a few mates the answer is obvious - just have a working bee for free beer

Assuming you only want it a little bit above ground level, all you need to do is peg out some boxing nice and level, screed down a sand base, drop in a bit of mesh, pour in concrete and screed off to top of boxing. Then, just sit back with that nice cold beer

[DavidG]

1. Why do you want it a bit higher?
2. Have you thought about using treated pine sleepers.

[rick_rine]

with my plastic water tank when I pumped up from the creek it caused minor vibrations in the tank . For this reason I would stick to sand as maybe the vibrations against the concrete may cause friction and rubbing on the plastic eventually leading to weakening the tank .
My 2 cents worth
Rick

[silentC]

Whatever you do, keep in mind that when full that tank will weigh over 4 1/2 tonnes.

Haven't had much experience with plastic tanks but with steel tanks, it's important that whatever they are on is flat with no undulations as it can cause the bottom seam to split. Probably one reason they recommend river sand is that it will conform to the bottom of the tank and support it evenly. I'm not sure I'd like to sit 4 1/2 tonnes of water on a base of pavers or bricks unless it was very stable.

[Bleedin Thumb]

No- probably the same reason those above ground swimming pools are set on a thick layer of sand.
And once again what is the advantage of raising it 100mm when the tank I guess will sit what 1.8m high?

[tourgy]

Thanks for the replies all.
The only reason I wanted it raised a bit was so that when the hole for the outlet gets drilled it is as close to the bottom as possible.
I'm not even sure if I am making sense here so bear with me.

If I dug out all the loose earth in a 2 sq mt area till I hit the clay it would cause the bottom part of the tank to be a few inches below the rest of the ground around it. Unless if course i filled up the 2 sq mt boxed area with sand and brought it back to the level of the ground around it. Which come to think of it is what I am probably supposed to do.

I can see where the recommendation of sand is coming into play. The only problem i have with that is that I still need a solid base to mount the pump on. Hence the original thoughts of the slab being layed. Plus if the tank is at the same level as the ground around it, how low can the outlet hole be drilled in?

What about those concrete paver type slabs? Would they be stong enough? Safety is of the most uppermost importance as well due to kids running around the back yard etc.

cheers
tourgy

[silentC]

Plastic tanks usually have the outlet pre-formed in the side of the tank, so you probably wont have control over the height. They're usually an inch or two from the bottom so that any crap that collects in the bottom of the tank doesn't block it up.

If you are fitting a pump, the height shouldn't make any difference...

[Felder]

The only reason I wanted it raised a bit was so that when the hole for the outlet gets drilled it is as close to the bottom as possible.

Tourgy,

DON'T make the mistake I made when I drilled a hole in my tank! I drilled it as low as I could, figuring that this would give me the maximum use of the water I collected.

Right now, I can hear all the bushies just shaking their head.....bet you blokes know what's coming up......

The hole I drilled was too close to the floor of the tank, meaning that the inside flange of the outlet pipe was hitting the floor, and not allowing the outlet pipe to poke through the hole squarely.

There was a very loud, very echo-ey curse word that emitted from the top of my tank when I found out what I had done, followed by much patching, painting, etc.

[Barry_White]

When I was with Lysaghts the tank manufacturers that I called on used to make what is called an earth ring which was just a ring made from tank iron which was just 200mm larger in diameter than the tank and then this was put on the ground and filled with sand and then the tank just sat on the sand.

You could do this with some treated pine sleepers and build it like a square retaining wall and fill it with sand and sit your tank on that.

The other method would be to make a tank stand out of steel purlins.

If I can find the design I will post it for that size tank.

[ausdesign]

We just installed about the same size on ground that had a reasonable slope.
rather than digging in & greating drainage troubles we built the ground up with t/pine perimeter & then compacted packing sand. - possibly looks a bit unsightly until the plants grow [round tank. square base]

[ausdesign]

There's an echo in here . . . I like the steel ring idea bazza

[Buzzer]

Tourgy,
What Felder said, also I would leave 2 to 3 inches of water in the bottom of the tank so it wont blow away in a storm.

My experience with putting sand as a base is the little digging critters find it easy digging, get under there and dig the sand out and make a home, leaving voids under the base.

I have levelled the natural earth(it has no rocks) under 3 poly tanks(7000 gallons each,for stock water) and so far haven't had any problems. They have been there about 5 years.

Of all the tanks I have seen around here, none have concrete pavers under them so I don't know how successful that would be.

Cheers
Buzzer

[MICKYG]

Tourgy,

We installed 10,000 litre which is on a crusher dust base, a circle of about 3 metres. The outlet pipe is about 100mm above the base, you do not want silt coming out of the tap every time you turn it on. Its been in two years now and never been below 1/2 full and is used to water the Vegie garden and beautiful cool drinking water for our houshold. We also installed a pre tank filter which dumps the first 50 litres off the roof.

Regards Mike.

[Barry_White]

There's an echo in here . . . I like the steel ring idea bazza

They need to be made from Aquaplate to prevent corrosion on the inside of the earth ring.