Thread: Concrete slab for water tank

Hi everyone,
Thanks for all the help so far. I think I will drop the idea of a concrete base and go with the manufacturers recommendation of the sand base.

Seems to be the norm from what you have all said. Makes sense about the sand allowing the bottom of the tank to mould itself into the sand.

My only problem now is what to mount the pump on. There is nothing but earth where the tank will be installed so I am not sure what to do about this. I could put it around the corner but that will make it 3-4 metres away from the tank.
Would this have any effect on the pumping power? Or does it make no difference what the distance of the pumpp is from the tank?

Cheers
tourgy

You can buy small pre-cast slabs about 400mm square and a couple of inches thick at hardware or building supplies.

Originally Posted by tourgy

but that will make it 3-4 metres away from the tank.
Would this have any effect on the pumping power? Or does it make no difference what the distance of the pump is from the tank?

Cheers
tourgy

Very little unless the feed pipes daimeter is so small that the friction caused by 3-4m of line reduces flow - very unlikely, given the pump is being fed with positive pressure from the tank. It would be a different situation if the pump was above the water source.

Assuming the pump will still be sitting on the same level as if it were beside the tank you should get the same amount of head from it.

Depending on how high you need to go, which is governed by the top of the tank in relation to your roof guttering, you could look into one of thos ready made concrete culverts. Check out your local pre-stressed concrete people. These things are shape like a square U and placed upside down. They act like a table for your tank, and the underneath area can be used for a doghouse, or firewood box etc:

If you use sand, it must be gently watered in then "critters" will have little effect. You might want to put a membrane between the sand and the tank as well. In the old galv days, we used tar-paper.

screw the pump down to a short piece of sleeper and just let it all sit on the ground

All interesting stuff, but what does the manufacturer of the tank you have bought recommend?

I have seen other manufacturer (Clark Tanks) recommend the following

1. Ensure the location of the tank is level, stable ground which has uniform compaction (free of soft spots). Do not locate large water tanks close to retaining walls or embankments without first consulting a professional engineer to ensure the ground is capable of supporting the weight of the full tank.
2. Ensure the surface of the site is free from sharp objects or stones and is compacted.
3. Spread a thin layer (approx. 20-40mm) of 3mm metal/crusher dust – bedding sand can be used but is prone to erosion – evenly over the level ground, at least 500mm more than the diameter of the tank. Once it is compacted and level you may then place the tank directly on top of this material. To assist with reducing soil erosion, back fill to first rib.
4. Ensure the metal/crusher dust is contained under the tank at all times and cannot be washed away. This can be achieved by diverting all run-off water away from the site and retaining the metal/crusher dust with some form of retaining structure e.g. cement strip, rocks or sleepers.

Tourgy,
The last thing I'd claim is to be is an expert on water tanks, but with the way this drought is going I think we'll all be a little wiser in the near future.
I've just installed a 5000 litre poly tank on a cracker dust base and I think that's the way to go.
I think if you use concrete it needs to reinforced because if and when it does crack the pieces don't move relative to one another in the vertical direction. I reckon the same would go for pavers etc, I think that if there is vertical movement you'd get a shearing force applied to the base of the tank and I'm guessing it could tear.
Anyway the cracker dust is cheap and easy to put down.
Here's a couple of pics which may be of some assistance

Ian

Thanks for all the help so far.

Like I mentioned earlier i will go with the manufacturers recommendation of a bed of river sand. But I do like the look of what Ian Smith has done.

Ian, Has that cracker dust been compacted with something? Or did you just lay it down and level it out before putting the tank on it.

I was going to make a border of house bricks, But may use something like what Ian has done as they are a bit larger and basically gets about the height I wanted off the ground. What are those concrete looking bricks called?

As far as where the tank will be located it will be at the back of the house as this is about the only lcation I have where it will collect a good amount of water. I Intend to put it about 30-50 cms away from the main wall. It will be rather unsightly. I can post a picture later.
This wont be a problem will it? As far as I can tell the earth around here is clay and very very hard. I tried to dig a small hole out the front once and gave up it was so hard.

The company is http://www.waterstore.com.au/index.asp and the price of the 4500 litre tank was $895 delivered with some fittings supplied.

Bit nervous of the location now because yes, when full it will be very heavy.

Cheers
Tourgy

Tourgy those large looking brick thingys are called Besser blocks. The crusher dust would need to be compacted with a plate compacter. If you dont the middle will sink and damage your tank. Proximity to the house is not an issue, you HAVE to make sure the tank has a level base to sit on.

If you consider a tank to be unsightly then just put a sheet of mesh around the 'visible' side and grow a passionfruit vine or a climbing rose or a potato vine or a star jasmine vine over it. One of these will have it covered in no time.

Pete

Tourgy,
Yep, zackery wot Doughboy sez

Ian

Thanks for the clarification on those bricks Doughboy and Ian.

As I dont have access to a compactor I may just go with the sand. Reading the instructions from the manufacturer they recomend a border of some sort of bricks then the sand. It does not mention anything about compacting it.

But they recommend the border of bricks after the tank is in its resting spot. Basically says build a level of sand 50-100 mm high, put the tank on, then border it with bricks.

Cheers
Tourgy

tourgy,
without a compactor your best bet would be to build a border and use fine sharp sand (plasterer's sand is ideal) and water it in. This will compact it. Don't use river sand as it's usually coarse and rounded and will not compact.

Mick

I dont have access to a compactor

Just about any plant hire place will have them for hire. As you're in Melbourne, I'm guessing there's a Kennards or similar in a suburb near you!

Originally Posted by journeyman Mick

tourgy,
without a compactor your best bet would be to build a border and use fine sharp sand (plasterer's sand is ideal) and water it in. This will compact it. Don't use river sand as it's usually coarse and rounded and will not compact.

Mick

That shows up the problem with local names for different products - sands in particular.

In Sydney River Sand - especially course washed river sand is used for paving bedding and is very compactable.

Beach Sand on the other hand is not compactable being fine, which is different to Perth I think?

Its all to do with the Gap Gradient Particle Size but you all know that, don't you.