Efficient Water Usage and Storage

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.