> Efficient Water Usage and Storage

Why be efficient in your water usage?

Good question! This all really comes down to the cost (in all senses) in the provision and maintenance of the water supply infrastructure. The better and more efficient you are a consumer of water, the less demand you are placing on the water supply infrastructure and ultimately on the environment and the local ecology. Also if the water demand as a group is reduced, the individual cost to the consumer should be less, so you are also saving yourself money in the long run.

Being water efficient

Efficient Water use is actually a three stage process:

• First, you need to collect the water in an efficient manner (i.e. get the most/best water you can)
• Second, you need to store the water in an efficient manner (i.e. least cost and most reliable to guarantee continued water quality),and
• Third, distribute and use the water in the most efficient manner (i.e. when to use and how to use it).

Each of these stages in their own, if done right, will bring water efficiency benefits; but you will get a sort of 'multiplier effect' if you do all three right. Now onto the finer details...

Efficient Water Collection

Unless you happen to live on a boat in a fresh water lake, collecting clean water is going to require some infrastructure development. 'Traditionally' there are 3 main ways to collect water:

• From suitable roofs
• From suitable bores
• From someone else..

The 'someone else' option is usually in the form of a 'pipe' from either a state water supplier or someone close to you who has excess water. With this option it is very likely you will pay according to consumption, depending upon the supplier this could either be very ecological or not very ecological at all (thinking Sydney here). This is good as a backup but you should not be dependent upon it for your day to day water usage, especially with the predicted price increases coming through.

Bore hole water collection

Bore holes can give you access to a large amount of water. Although do be very careful with this, as firstly the quality of the water you 'pull' might not be all it is claimed to be, and secondly you might be paying through electrical pump costs to 'pull' the water. Also if your neighbors are doing the same, that increases the demand on the water, which could make the water recede and you end up with a dry bore! Also pulling water from the bore could effect the ground water level, so damaging the environment else where (drying up rivers, etc)

Roof Rain water collection

Roof rainwater collection is perhaps the most environmentally friendly (or least damaging) way to harvest water. It has several distinct advantages:

• The water by volume is 'free', i.e. you don't pay per mega litre, etc;
• The water, assuming a clean roof and infrastructure, can be clean enough to drink! (where do you think the water in your tap actually comes from?)
• Given the 'sudden downpour' nature of most rain events where I live, the impact of you harvesting rainwater is quite minimal as its literally 'washed out' compared to amount of water just falling to ground. Also when your tanks are full they will overflow to ground as well. Just think of it as borrowing the rainwater to later put back into the natural system at your deciding

The Roof

So how do you go about this collection from the roof? Firstly; assess which 'planes' of your roof are worth collecting from. Some roof planes may be heavily overshadowed by trees so would collect a lot of leaf litter (check the gutters), this taints the water. You can put on leaf guards on the gutter, but in some cases the benefit would be marginal. Also do a cost/benefit analysis on the smaller/harder to reach roof planes; they may not be worth the plumbing effort to harvest. I have one roof plane on my Cabana that was the wrong side to the tank with not enough fall and it was overshadowed by trees, so I left it out.

Next, work out what the square meterage is that you are collecting from as a 'flat' vertical view. i.e. a roof at 45 degrees will not collect the same as a roof at 20 degrees. Use your house plans for this and just measure straight off the plan, do not climb your roof to get these figures! Round down to the nearest square meter.

Next, try and find details of what the mean annual rainfall is for your area in millimeters. BOM and some local councils will be able to point you in the right direction for this; try their environmental departments.

Next, multiply the square meters by the millimeters of rainfall you have (i.e. 35 sqm x 20 mm = 700) - this figure is your total harvested LITRES of water per year during an average year - should be quite a bit for a large roof!

Next, work out the water consumption you can 'attribute' to the harvested water; i.e. don't count drinking and cooking water if you are on mains supply. Charts like this abound across the internet, plus several interactive calculators. You are aiming to end up with a total harvested water usage figure for the year. Also make good use of your water utility bills if you have them.

Okay so far? Now subtract the total harvested water figure from the harvested water usage figure - if the result is negative, this indicates that for some part of the year there is a good chance you will need to use other water sources (i.e. mains or bore) to 'top' you up. If its positive, there is a good chance (given big enough storage) you won't need topping up.

Check your gutters (Australia)...

If your house has had new gutters put on it in the last 10 years, do check to make sure that they are not the 'high front' variety?  i.e. the front of the gutter is higher than the back of the gutter facing the wall. Why? Well, this particular style of gutter has been rather popular as it looks attractive and is cheap to install, but the downside is that in a heavy rain downpour, when the water volume is such that the gutter down pipes backup, the water will find its way out by the next lowest point, which will be the back of the gutter directly mounted onto the wall! The big negative with this is that either the outside wall is made wet, or if the gutter is mounted right to the top of the wall (as it is on most modern houses), it will flow inside into the wall cavity and make that nice and wet.. This will lead to rot, termites and the possible structural failure of your property!... You have be warned, so do check!

How big is your water tank?

So how do you 'size' your water tank? The trick here is to have enough storage to 'carry you through' the periods of no rain given sufficient prior rain. The above positive/negative figure will give you a steer on how likely being able to carry through will be, the more positive the easier with adequate storage; the more negative the less worthwhile as a goal this is (so don't bother getting such a big water tank).

The size you need also depends a lot on your rain fall patterns - if you have well defined periods of the year that are 'wet' and 'dry' then you should aim to collect as much as possible to carry across into the dry periods. If its more random and equally distributed across the year, then you just need to hold enough to 'flatten out' the random distribution (i.e. a quarter of a years total rainwater would be more than adequate). Your consumption of the water also comes into play, if you consume it all before it can be saved over the medium term, a large tank will spend most of its life empty!

Although, from talking to many people on this issue, I always hear the same story; namely 'I wish I had got a larger tank'. I think this is more down to the changing weather patterns which have condensed what was previously a months worth of rain into a day!

What type of water tank?

Water tanks come on many different types, shapes, sizes and colours; but can be grouped by final insulation location, as follows:

Buried in ground

These are either plastic or concrete. Plastic water tanks will be supplied as a whole unit that is 'dropped' into the hole and filled over. Concrete water tanks require form work, pouring, topping off and covering over. Plastic is in essence quick and easy, concrete slower but more 'solid' - i.e. should last a lot longer.
Where it is viable to bury your tank is determined mostly by your budget and the ease with which the required hole can be made. Also be aware of ground water on the site, if this pools in the hole, you can end up with the empty tank literally 'floating' out of the hole...

Under the house

Unless you are building a new house, your only real option here is what are known as 'bladder water tanks' - in effect a big rubber bladder that rests in a special frame in the void space under your house. Big plus is that you don't have to dig holes or take up yard space with a water tank. Downside is that the capacity is usually limited and you pay a premium.

Above ground

This is where you will find by far the biggest variety. Everyone and his wife is either making or selling some form of above ground water tank. The trick here is to use the right 'type' of tank for the size and expected life.
Above ground small plastic water tanks - These go up to around 2000 litres and come in all manner of shapes: round, square, cylinders, etc. They are mostly designed for use on the smaller plot where finding somewhere to 'fit in' the tank can be hard. Often they end up mounted on a small stand. Big downside with these is the lack of water storage and the fact UV will degrade the plastic - so fixed life span (or keep them out the sun and/or paint them).

Above ground big plastic water tanks - These usually go upto 15k litres and are shipped to site whole and ideally 'dropped' right onto a special sand based pad that becomes their home. The big plus here is that its ready to go. The big negatives is that they don't do well in a bush fire and the UV will degrade the plastic over time - so have fixed lifespan. See Nylex Water Solutions for tanks of this type.

Above ground metal water tanks - Basically a big metal 'water butt' with some internal treatments to reduce corrosion effects. These can go up to 150k litres typically. Cheap but the fact the metal is performing two roles (structural and water lining) means they are susceptible to failure due to movement - so they are often mounted on frames or towers as part of the package. Also rusting puts a limited life on them.

Above ground concrete water tanks - Basically a big reinforced concrete box or cylinder. These go up to the millions of litres with a cost to match to boot. No problems with rusting, although be careful on settlement as it could crack the tank. Also no way to move it once its in place, so be darn sure you wanted it there.

Above ground metal water tanks with plastic liner - Think of this as the 'bladder tank' going outdoors. The metal provides the enclosing framework, whilst the liner does the job of keeping the water in. Big win here is that settlement won't loose you water, and rusting doesn't make the tank leak. Sizes up to millions of litres. See Pioneer Water Tanks for more details. Another plus is that the liner is often 'food grade' - so good to drink from direct.

Is it all worth doing??

A whole load of factors come into this: some you can quantify, some down to a lifestyle choice.. The simple factual information is best worked out over the expected lifetime of the various solutions you have available. i.e. look at things over 10 years at least. Most good water tanks should still be functioning well after 10 years with a little bit of TLC. So work out the amount of water 'saved' by the water tank compared to say mains water, i.e. the cost of the tank water if you had it from the mains. Subtract from that the actual full cost of the water tank and you get the nominal cost now amount (no depreciation or price adjustments) you will save (positive) or loose (negative) from utilizing a water tank over 10 years..