# Forum Home Renovation Water Saving Garden Ideas  Substrate for water tank?

## grantbudd

Looking to get a 3000l slimline water tank to set up for garden watering in qld. I'm on a sloping block and the tank needs a flat surface to sit on. What is the best way to set this up? It's soil so I was thinking dig out until level then make some form work and concrete a base and add some wire to reinforce it?  
Thanks  
Grant

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## cyclic

> Looking to get a 3000l slimline water tank to set up for garden watering in qld. I'm on a sloping block and the tank needs a flat surface to sit on. What is the best way to set this up? It's soil so I was thinking dig out until level then make some form work and concrete a base and add some wire to reinforce it?  
> Thanks  
> Grant

  Crusher dust with a bag of cement mixed in is cheaper than concrete and just as good. 
Have a look at this site     National Poly Water Tanks | Strong Australian Rain Water Tank | Servicing QLD & NSW 
ps. 3000 Litre is not big enough to make a difference. A pump running at 24 litres/min will give just over 2 hours watering if running from full tank.

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## grantbudd

Wow that is low at only 2 hours. Didn't think of pump outputs thanks. Problem is we don't want a massive tank but eathier way I have to dig down so I guess I could.  
What size do you recommend? I'm on town water too and will have a drought tolerant garden consisting mainly of palm and native plants. Mainly for the grass as we would like a green garden.  
Garden is approx 120m2 and front is around 60m2. No issues with rain today it's been pouring down for over 30hrs here and is set to carry on for days.  
Could fill a tank easilly

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## Bloss

So long as the soil is stable & and level crusher dust as described is fine - so long as it can't be washed away, but mortar batters around the edge can stop that. 
As has been said you will be surprised how much water you might need.  Simple enough to work out - most regular 12mm taps without a restriction device will flow at around 10-16L/minute (depends on local water pressure). Simple way to find out is to get a 10L bucket run the tap into it at fully open and time it for one minute to see what amount flowing. Of course if you have more than one tap open then the flow rate will reduce. 
From those numbers you can see that a full 3000L tank will be empty in 5 hours at 10L/min (and it will not fully drain the 3000L). If the flow is 12 L/min then around 4 hours to empty, if 16L/min then 3 hours to empty and so on. 24L/min would be a high flow rate. So tanks can supplement your town water (and remember they only refill when they are not already full . . . so you should try to use up any tank water first so that you capture the maximum amount when it rains next). But look at the costs carefully as town water is cheap in most places. And also remember that when there are droughts and water restrictions your tank will likely be empty too . . . or give you only that few hours anyway. 
To save money and water it us usually better to spend money on efficiency measures such as underground soaker type systems for lawns and weeper hoses for gardens - most of these are easy DIY projects and cost much less than tanks.

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## cyclic

> So long as the soil is stable & and level crusher dust as described is fine - so long as it can't be washed away, but mortar batters around the edge can stop that. 
> As has been said you will be surprised how much water you might need.  Simple enough to work out - most regular 12mm taps without a restriction device will flow at around 10-16L/minute (depends on local water pressure). Simple way to find out is to get a 10L bucket run the tap into it at fully open and time it for one minute to see what amount flowing. Of course if you have more than one tap open then the flow rate will reduce. 
> From those numbers you can see that a full 3000L tank will be empty in 5 hours at 10L/min (and it will not fully drain the 3000L). If the flow is 12 L/min then around 4 hours to empty, if 16L/min then 3 hours to empty and so on. 24L/min would be a high flow rate. So tanks can supplement your town water (and remember they only refill when they are not already full . . . so you should try to use up any tank water first so that you capture the maximum amount when it rains next). But look at the costs carefully as town water is cheap in most places. And also remember that when there are droughts and water restrictions your tank will likely be empty too . . . or give you only that few hours anyway. 
> To save money and water it us usually better to spend money on efficiency measures such as underground soaker type systems for lawns and weeper hoses for gardens - most of these are easy DIY projects and cost much less than tanks.

  Gotta agree with Bloss, at present rates of $2.65/kl you can buy a lot of water for the $1000 to $2000 to set up tank, pump etc 
eg $1000 buys 377000 litres

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## johnc

We use two 3000l slimlines to water the rear garden, the grass fends for itself. The garden is drought resisitant and we don't deep water using the tanks to give the plants a boost on hot days or after dry spells. We have never run out of water although one tank is now empty the other almost empty after the recent dry spell. Hard to justify the cost on usage, our basic connection charge is just over $300 for four months with usage over that. We water the front garden from grey water, I think the tanks will pay themselves off over time but we might be 105 by then. If you have the space a round 10000l would be the minimum I'd put in but if like us contrained for space the slim line will keep the bills down. 
Ours sit on a concrete pad with reo, it wasn't that expensive to box and pour and I'm not a fan of sand/cement mixes where they can be seen, you need to make the base 50mm wider than the tank.

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## grantbudd

When you say $300 for connection is that connection to your rain water tanks? Our garden is dry and think it would love a bit of water during hot days as peoples gardens are almost dust here on sunny coast. Still raining after 4 days non stop so I could have filled the tank several times over by now!

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## johnc

> When you say $300 for connection is that connection to your rain water tanks? Our garden is dry and think it would love a bit of water during hot days as peoples gardens are almost dust here on sunny coast. Still raining after 4 days non stop so I could have filled the tank several times over by now!

  No the $300 each four months is for the privilage of having town water, for a family of four the bill is going to be at least $450 if you want a green garden $600 per four months would be the norm and that is `without going overboard. Needless to say most lawns around here are brown.

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