Question What size rain water tank?

[Steve]

Hi All,

I'm currently working with a builder to design a house to plonk on our newly purchased land.
The land has about an acre of usable dirt and I plan on doing a few self-sufficency things such as veggies, chooks, and fruit trees.
We want to make it pretty lush so plan to have a myriad of other garden beds around the place. (eventually)
The house is in SE Qld (Australia) so it does get good rainfall around our summer months.

I told the builder I want rainwater plumbed for toilet flushing and of course the garden.
The question now is what size?

I've found all sorts of websites that allow you to plug in figures and it gives you an estimated size but I was wondering what experience you guys might have. What size do you have, what size garden, is it enough, would you wish for bigger?
I want to get the biggest that will give me the best bang for my buck and not be an overkill. Maybe a difficult question as there are so many variables but you can't beat experience and that's where you guys come in!

Would love to hear your input.......

 

[Letsgokate]

Great question that I'm sure those who have the setup you are planning can better answer.

Our experience is put in as many tanks as you can reasonably afford and have the space for, of course without looking silly. Yes we get a reasonable amount of rain in SE Qld, like this week. In fact this year we have had a lot. But keep in mind several years ago, our dam levels were extremely low and we were on tough water restrictions.

Water is expensive and I hate flushing money down the loo, so great you will have the toilets plumbed in.

 

[Mark]

We have a small 1500 litre tank off the house just to fill the odd bucket - it's pretty handy but just a gimmick really. Our main tank is 16000 litres and through the dry season here in SEQ it's pretty easy to empty it just on watering the garden particularly if no rain has fallen for several weeks.

If we don't get early spring rain (which is often the case) then a dry spring can be tough on food plants and especially fruit trees because the sun in our part of the world is getting pretty harsh coming out of winter yet if there's no rain to compensate the deeper soil moisture starts to dwindle leading to stress. At a time when many fruit trees are ramping up coming out of winter, water is very important to set the coming year so we find ourselves using the most water leading up to the rainy season.

We have a bore to draw water from and it feeds our tank - in some years I will refill our 16000 litre tank 5 times between early spring and midsummer if rain is scarce over this period. We do have about 80 + fruit trees (not including the vegetable garden) so it's a fair amount to water - and it's not always targeted at the base of each plant because of employed watering systems which are convenient but not always the most conservative. However, sometimes a sprinkler in the orchard or auto-watering system in the vegepatch is the most practical way to get water on the garden.

It also depends if you intend to maintain an ornamental garden (non-native) and lawn as this will take more water. There's also the use of treated waste water which if used right can save on using good rain water - will you have a septic or town sewage?

Will you be also connected to grid water? I assume you are since only using the tanks for toilet flushing... But, I mention it because as expensive as town water is you have a fail safe water supply to fall back on if you do run out of rainwater - generally less expensive than trucking water into your property.

For those who are not connected to grid water (like my sister) the size of water tanks is more critical and should lean towards overkill because you always seem to use more water than you expect. As my sister and brother in-law would agree trucking in water is an expensive pain in the bum but the worry if and when you'll run out is just as bad so in those cases as much storage water as possible (within affordability and space) is recommended.

 

[Steve]

Good points Mark.
I will be connected to grid water so I would love the tank to be big enough to cover the garden for 90% of watering during the year.
I know the dry spells can throw a spanner in the works but its just my thoughts.
There will be some grass but I'm hoping to have as little as possible as I know it loves the water.
And good point on the treated waste water. I will be on septic so that treated water can be fed onto non food plants too.

My initial thoughts were to have a 10,000 l tank but I'm thinking of doubling it to 20,000 l.
By the sounds of it I could probably go to 30 or 40,000 l and still find a use for it all.

Cheers.

 

[stevo]

heh, I'm at the small end of the scale here, 1 x 2500L beside the house and 1 x 3000L at the back fence and they're connected by a hose so work together.

The toilet has two inlets, one tank water and one mains water. When the tank water gets low I turn the mains tap on beside the toilet.
The shower water goes out the lawn
I only use tank water to hose the garden and top up the pond, i'm fairly tight with my water usage and rarely run low on tank water.

I'm a supporter of having more than you need and i'd like to get more scattered around the yard and connected together.

One big 40,000 would be awesome, or if you wanted to hide them in various spots you can get a few smaller ones.

PS: sounds exciting !

 

[Mark]

My initial thoughts were to have a 10,000 l tank but I'm thinking of doubling it to 20,000 l.

Yeah definitely more than 10,000 litres 20k would be good and with a backup of town water perhaps all you need... if you had the space maybe allow room for another 20k tank if you need to add in the future?

You can use treated septic waste water on fruit trees BTW - this can be very handy. It also helps if you have it setup with the ability to move the outlet hose for the waste water to different areas if required.

PS: sounds exciting !

I agree!

 

[Ash]

The more the merrier I also suggest especially if you have the roofing to support it. You'll be surprised how quickly a 20,000L tank will run dry using it on your garden alone, even a half acre one.

Where I am hoping to be in a couple of years there is no town water and only a small bore for backup so the home and big shed are connected to 40,000 gallons of tanks which may not be enough for a family to get through a dry season even if only used for domestic purposes.

So try and upsize on water tank if you can and have the room to fit it, particularly if there is no bore available.

Currently I have a measly 2,000L tank and it barely takes care of my small 650 sq m backyard but it has been a handy little tank.

 

[Letsgokate]

You can use treated septic waste water on fruit trees BTW - this can be very handy. It also helps if you have it setup with the ability to move the outlet hose for the waste water to different areas if required.

It might be ok to use this water on fruit trees where it's not been sprayed directly onto the fruit. From my understanding this water can't be used on fruit, veggies where the water could or would be sprayed directly onto the food. Just saying

Agreed it is handy to be able to move it around, not long after we moved in and it was very dry we moved it around a lot, had nice green circles of lush green grass everywhere.

When we lived west of Toowoomba we were on tank water only, didn't get much rain and we had to buy water in every month. So it's great to have some sort of backup water supply, like town water.

 

[Ash]

When we lived west of Toowoomba we were on tank water only, didn't get much rain and we had to buy water in every month.

Which part? It's amazing the change in landscape going a few kilometres east and west from the range.

 

[Letsgokate]

Meringandan, not far from Highfields

 

[Mark]

It might be ok to use this water on fruit trees where it's not been sprayed directly onto the fruit. From my understanding this water can't be used on fruit, veggies where the water could or would be sprayed directly onto the food. Just saying

Correct - fruit trees filter out any bad stuff before it gets into the fruit but no don't spray the fruit with septic waste water! Having said that, my envirocycle service guy said the waste water coming out of our septic could actually be safely consumed "in theory" due to it's filtering and chlorine treatment before being pumped onto the garden... Of course you wouldn't, but it does go to show how well some of these mini treatment plants can work. Just so there's no confusion, waste water from a septic should only be used to water the base of fruit trees not all over the foliage or fruit and never used in the vegetable garden.

 

[bearded1]

Where I am hoping to be in a couple of years there is no town water and only a small bore for backup so the home and big shed are connected to 40,000 gallons of tanks which may not be enough for a family to get through a dry season even if only used for domestic purposes.

Hey Ash,
We have 87,000 litres of water storage and that took us through the really dry season last autumn/winter. We have 3 dwellings which equates to six people and two washing machines and one of those people does not know the meaning of a short shower. 40,000 gallons is approx. 170,000 litres. Should be heaps for a significant dry spell with even moderate care.
bearded1

 

[Ash]

That's good news, because by the time we get there I may have more than one person who believes that water supply is infinite...

 

[Ash]

Meringandan, not far from Highfields

Yes, I know it. Lovely landscape out there. Seem to be a few of us in this local area.

 

[Flatland]

I know this is an old thread but reading it made me wonder about people's water usage. Ash was concerned that 40,000 gallons would not be enough for household use. We lived on 30,000 galls for everything, house animals garden, fruit trees & rarely got through more than half of it by the end of SA's very dry summers. On the other hand our neighbours with a bore used to use 50,000 galls a month. They had a large water hunger ornamental garden, all azaleas camillas etc

 

[Ash]

I've been on the property for almost a year now and haven't run out of tank water from our supply so far, and we did have an uncharacteristic summer/autumn (dry). The winter and spring thus far has been cold but more wet than usual, so the plants are getting some mkoisture without me having to water them so much (plus I don't have the time). Life gets away from you like that in my line of work but one day I might get to enjoy the great outdoors in the nice location we have.

 

[Steve]

So I ended up with 20,000l under the house so it's out of the way. Could possibly fit in another 10,000l but I wasn't sure during the building stage if I would need that room for something else as it's also my shed area for tinkering around.
I've had 200m2 of turf laid in the last month and boy does that use up the water. It needed to be watered twice a day for the first week or two and then it can be slowed down a bit. My tanks were full and within days they were empty!
And we haven't had more than a few mm of rain during this time too which makes it worse. Now I know how the farmers feel.
So luckily we have town water too so I can still water the green stuff and not have it die.
The other thing that steals my water is the pool. It evaporates like its metho! Well not that bad but still noticeable.
I hate topping up the pool with town water as it just feels like a waste. But not much I can do until we get some more decent rain.

 

[Flatland]

20,000l is a pretty small tank when it comes to watering. Are you doing any clothes washing? Water from a washing machine is great for lawns. Always a good idea to use water more than once. Also if you are on septic it is good to limit the amount of water & detergent/soap that goes into the septic tank
Water use is definitely something that every Aussie should be concerned with

 

[stevo]

POOL!!? You have a pool?!! Pools and trying to conserve water?

I vote this years xmas bbq be held at Steve's place

 

[Steve]

Yeah @stevo, I have a pool. It was the only non-negotiable request the wife had for the new house. It's the first one I've had so it's all still really new to me but I must say there's nothing better than floating around after a hard day digging.
Welcome anytime, payment will be a truck load of water to fill the tanks.

@Flatland all our grey and black water goes into the water treatment system and comes out as 'clean' water that goes into the non-eatable area of the garden. The grass in that area is as happy as a pig in sh1t.
20,000l is so much more than my old place that only had 2000l but I know what you're saying. I really didn't know during the build stage how much water I'd need so i found an online tool that you feed in your needs and the location and it works out roughly what size tanks you should get. I think mine worked out under 20,000l but I rounded it up. I think my neighbour only has 10,000l so I'm guessing he wasn't really sure either.
One thing I'm happy about is that every part of my roof feeds the water tanks and with extra large gutters I'm yet to see any wastage from them overflowing. When we do get rain they fill up pretty quick which is great.