Water Tanks - Starting off.
I'm not going to spend a long time arguing the benefits of why you should use water tanks. This is more about application. But, water tanks are a tried and true, safe and cost effective way to provide water security for you, your family, animals and your garden.
I'm not going to spend a long time arguing the benefits of why you should use water tanks. This is more about application. But, water tanks are a tried and true, safe and cost effective way to provide water security for you, your family, animals and your garden.
This section will detail the use of water tanks for off-the-grid living. This can be a tricky subject to approach well as they are more than just over-sized buckets you rig up to a catchment. Or at least they should be. I've lived off rain-water as my main drinking source for as long as I can imagine and I was surprised when I first jumped into researching this topic. People are actually concerned about the quality of rain water. Barring living in a heavily polluted city or near a heavy-industry center, rain water is likely to be the be much better for you than any municipal water sources. So long as you filter your rain water correctly, or even chemically treat it if you're really concerned, then I cannot imagine any problems in your water safety. This is enough I will talk on this aspect of using tanks.
Before choosing tanks for your home you need to consider your yearly/monthly rainfall levels. If you get 400mm a year then tanks are less attractive as a water source than if you have 700mm or more of rainfall.
You also need to consider the catchment area of your home and/or shed or other collection means. Obviously you're going to need the roof guttered and have pipes connecting to the tank. The most accurate way to do it is to take your house plans, and find out the square meters (m2) of the roof. Taking into the pitch of the roof typically the number is within 1.1 and 1.3 times the flat area given on a house blue prints.
Combining the figures from the annual rainfall, and the square meters you can calculate your possible water collection. Let's get some numbers out of the way; One 'millimeter' of rain on one square meter of roof equals one liter.
Before choosing tanks for your home you need to consider your yearly/monthly rainfall levels. If you get 400mm a year then tanks are less attractive as a water source than if you have 700mm or more of rainfall.
You also need to consider the catchment area of your home and/or shed or other collection means. Obviously you're going to need the roof guttered and have pipes connecting to the tank. The most accurate way to do it is to take your house plans, and find out the square meters (m2) of the roof. Taking into the pitch of the roof typically the number is within 1.1 and 1.3 times the flat area given on a house blue prints.
Combining the figures from the annual rainfall, and the square meters you can calculate your possible water collection. Let's get some numbers out of the way; One 'millimeter' of rain on one square meter of roof equals one liter.
Then, calculating the approximate amount of rainwater you are likely to harvest, use the following formula:
Water volume (Liters) = average annual rainfall (mm) x coefficient of runoff x roof area (m2)A coefficient of runoff of 0.9 can be usually used to obtain a rough estimate (this is to factor in loss of water in this process from possible overflowed gutters, wind, heat, leaks, etc).
An example of this formula in action:
If you were to have a roof with the total area of 100m2
And, lived in Perth having, say, 700mm of rain a year.
Then this would be your formula and answer:
100m2 x 700mm x 0.9 = 63,000 Litres
Now, considering the average person according to Water Corp. uses 280L per day. This might seem a lot of water but by the time you factor in the average household having gardens needing watering, cars being washed and showering, dishwashers, washing machines, toilet usage, drinking etc. you can start to picture where it all goes. From this we can put a fair 'guestimate' of 700L per day of water use. Dividing the 63,000L by 700L you end up with a mere 90 days of water of completely full tanks. Now, that leaves the other 275 days a year without water. Not good.
There are two solutions to this; Get more water, or use less.
Getting more water could involve the use of a bore or spring to supplement rainfall, or getting water trucked in (hopefully only in emergencies). Trucking water in is not every ecologically friendly or very off the grid. You could also improve your water catchment abilities by connecting more catchment to your tanks. If you have sheds that are unconnected, then connecting them to tanks, etc.
The second solution; using less, I think is the better option where practicable.
Firstly with this, let's tackle showering. Showering with a water saver head can use half the water a typical head will waste. Showering without a water saver head can use up to 20L of water a minute (upto 25-30L/M). Now, if you have luxurious 10, 20 or 30 minute showers you can see how the per capita average of water can be so high. If you reduce your showers to 1-3 minutes just to get the necessities done then you're saving huge water amounts right there.
If you have a family of four, and they've all been showering for 10 minutes each with a non-saver head, per day, then that's easily 800L used a day. This isn't even getting to the rest of your water use. Now, if you drop your showering time to 2 minutes, and use a water-saver head (Between 10L and even as low as 6L per minute.) then you're down to only 80L of water when calculating with a 10L head. Tiny in comparison.
After showering there's toilet usage. Ideally you'd use a non-flushing composting toilet, without the usual minimum efficiency standards of 5.5L per flush (or in a dual flush 9L/4.5L respectively) you save a lot of water right there, assuming that family of four only uses the toilet 2 times a day each that saves 44L a day if you work off 5.5L per flush. If you're the sort or person(s) that use the big flush every time then that would save 72L per day.
Obviously and easily now we're well into the negative numbers when compared to the usual liters use for a family of four in Western Australia.
Using super efficient washing machines, hand-washing dishes and having water saving taps, turning them off as fast as possible can save further water again. It is easily conceivable that using these methods a family of four could reduce their total daily water usage to well within 330L. Only a smidgen more than a typical person currently consumes.
Considering the average 4 bedroom home has a roof-area of around 200m2 then a family living in Perth with the average rainfall of 700mm could collect 126,000L of water in an average year. This is quite enough to supply the water-wise home with enough water for that family of four.
You will now cry; "I don't have enough space in my small urban block to house huge water tanks." Well there are several things to consider. Talking to your local tank-man and water collection expert they will tell you your tank needn't be so large as to be able to hold 126,000L as, that's quite over the top. Even if you can only fit a small 3,000L-6,000L tank down the side of your block you can usually supply yourself quite easily with enough drinking water for a year.
Up in Kalamunda, in my parents home they've had a drinking-tank setup for years and years now that's about 5,000L, us as a family of four could and would drink from the tank all year round.
You can also consider underground tanks to take over more of your water supply needs and if you've got an acre or a few you could seriously consider investing in a self sustained water future.
If you were to have a roof with the total area of 100m2
And, lived in Perth having, say, 700mm of rain a year.
Then this would be your formula and answer:
100m2 x 700mm x 0.9 = 63,000 Litres
Now, considering the average person according to Water Corp. uses 280L per day. This might seem a lot of water but by the time you factor in the average household having gardens needing watering, cars being washed and showering, dishwashers, washing machines, toilet usage, drinking etc. you can start to picture where it all goes. From this we can put a fair 'guestimate' of 700L per day of water use. Dividing the 63,000L by 700L you end up with a mere 90 days of water of completely full tanks. Now, that leaves the other 275 days a year without water. Not good.
There are two solutions to this; Get more water, or use less.
Getting more water could involve the use of a bore or spring to supplement rainfall, or getting water trucked in (hopefully only in emergencies). Trucking water in is not every ecologically friendly or very off the grid. You could also improve your water catchment abilities by connecting more catchment to your tanks. If you have sheds that are unconnected, then connecting them to tanks, etc.
The second solution; using less, I think is the better option where practicable.
Firstly with this, let's tackle showering. Showering with a water saver head can use half the water a typical head will waste. Showering without a water saver head can use up to 20L of water a minute (upto 25-30L/M). Now, if you have luxurious 10, 20 or 30 minute showers you can see how the per capita average of water can be so high. If you reduce your showers to 1-3 minutes just to get the necessities done then you're saving huge water amounts right there.
If you have a family of four, and they've all been showering for 10 minutes each with a non-saver head, per day, then that's easily 800L used a day. This isn't even getting to the rest of your water use. Now, if you drop your showering time to 2 minutes, and use a water-saver head (Between 10L and even as low as 6L per minute.) then you're down to only 80L of water when calculating with a 10L head. Tiny in comparison.
After showering there's toilet usage. Ideally you'd use a non-flushing composting toilet, without the usual minimum efficiency standards of 5.5L per flush (or in a dual flush 9L/4.5L respectively) you save a lot of water right there, assuming that family of four only uses the toilet 2 times a day each that saves 44L a day if you work off 5.5L per flush. If you're the sort or person(s) that use the big flush every time then that would save 72L per day.
Obviously and easily now we're well into the negative numbers when compared to the usual liters use for a family of four in Western Australia.
Using super efficient washing machines, hand-washing dishes and having water saving taps, turning them off as fast as possible can save further water again. It is easily conceivable that using these methods a family of four could reduce their total daily water usage to well within 330L. Only a smidgen more than a typical person currently consumes.
Considering the average 4 bedroom home has a roof-area of around 200m2 then a family living in Perth with the average rainfall of 700mm could collect 126,000L of water in an average year. This is quite enough to supply the water-wise home with enough water for that family of four.
You will now cry; "I don't have enough space in my small urban block to house huge water tanks." Well there are several things to consider. Talking to your local tank-man and water collection expert they will tell you your tank needn't be so large as to be able to hold 126,000L as, that's quite over the top. Even if you can only fit a small 3,000L-6,000L tank down the side of your block you can usually supply yourself quite easily with enough drinking water for a year.
Up in Kalamunda, in my parents home they've had a drinking-tank setup for years and years now that's about 5,000L, us as a family of four could and would drink from the tank all year round.
You can also consider underground tanks to take over more of your water supply needs and if you've got an acre or a few you could seriously consider investing in a self sustained water future.
You also need to find out when most of your rain will come. If it is typically spread out evenly then you will likely need smaller tanks. If the rain typically comes in larger volumes in shorter periods say, most of it in 3-4 months then you will be requiring larger tanks to be able to cope with the larger downpours and store for the less rainy periods ahead.
You should also not have one large tank. Multiple tanks are preferable for several reasons. If you have damaged tanks (holes, impacts - tree branches falling over/on them etc. then it's not to big a deal if you have four tanks than if you have one large one. Also, having smaller tanks allows you to move your stored water around allowing you to periodically clean your water tanks if/when needed without having to drain your hard collected water into nothing. Having several tanks makes it easier to move them about also. If you plan an extension, renovation or decide you want to collect the water from your shed instead of the homestead then it's much more possible to move your tanks that way.
You should also not have one large tank. Multiple tanks are preferable for several reasons. If you have damaged tanks (holes, impacts - tree branches falling over/on them etc. then it's not to big a deal if you have four tanks than if you have one large one. Also, having smaller tanks allows you to move your stored water around allowing you to periodically clean your water tanks if/when needed without having to drain your hard collected water into nothing. Having several tanks makes it easier to move them about also. If you plan an extension, renovation or decide you want to collect the water from your shed instead of the homestead then it's much more possible to move your tanks that way.
I hope this was helpful to those looking at sourcing their water via tanks.
Some sources used in my article: www.environment.gov.au, www.waterrating.gov.au, www.watercorporation.com.au, www.bom.gov.au, and linked here: www.home.iprimus.com.au/foo7/tank.html is an excellent calculator website for water-tank mathematics.
Other topics I hope to write about soon include:
Some sources used in my article: www.environment.gov.au, www.waterrating.gov.au, www.watercorporation.com.au, www.bom.gov.au, and linked here: www.home.iprimus.com.au/foo7/tank.html is an excellent calculator website for water-tank mathematics.
Storing And Moving Water - Water systems, Rainwater safety, Filtering roof water
Water Tanks - Patching up a tank, Concreting a water tank, How to build a water tank, Ferrocement tanks
Drilling For Water - Hand dug wells, Water from the rock, Boring out water
Solar Distillation - Fresh water in dry places, Solar survival stills, Stepped water stills
Moving Water - Bucket pump, Hydraulic rams, building your own hydraulic ram, Fuel-less plata pump, waterwheel pump
Household Water - Refining a bush shower, 12V Bush Pump, Household plumbing
Sanitation - Human Wastes, dry pit loo, composting toilet, Two-holed dunny, Improved pit toilets
