• Home
  • Services
  • About
  • Contact
  • Tank Info
    • Gardening
  • Blog

Water Tanks Melbourne

Your Guide to Choosing a Water Tank

Water Tanks Melbourne

Owning a rainwater tank (or even a few) continues to become more common in Melbourne because of changing weather patterns and a higher demand on town water supplies due to population growth.

Also, a number of councils now require new houses to be plumbed into a rainwater tank for toilets and laundry use.

​More and more households are installing water tanks of all types, shapes and sizes, so we have put together this guide on buying a water tank in Melbourne.
  • Buying a Rainwater Tank
  • Types of Water Tanks
  • Metal Water Tanks
  • Polyethylene (a.k.a., plastic) Water Tanks
  • Fibreglass Water Tanks
  • Concrete Water Tanks
  • What Size Water Tank Should You Purchase?
  • Rainfall and Catchment Area
  • What is the Main Goal?
  • Collecting Your Rainwater
  • What Size Water Pump Will You Need?
  • Installing an Above-Ground Water Tank?
  • A Summary of What You Should Consider When Buying a Water Tank

    Contact Us

Submit
Two large poly water tanks on a house in Melbourne

A group of different sized and coloured water tanks
Rainwater pouring out of a tap attached to a tank
Poly water tank on a bed of crusher dust bordered with timber

Buying Rainwater Tanks

When it rains outside, your main goal is likely to stay indoors and stay dry. However, you can turn a rainy day into an opportunity if you install a water tank to catch some of the water falling from the sky. By doing this, you can reduce the environmental impact your home and family has by decreasing the demand on public water supplies and by reducing the runoff that is sent to the oceans and rivers. Even better, you can reduce your water costs over time.
Modern rainwater tanks aren’t just round, big, and an eyesore – they are available in all shapes, sizes, and materials, which means you can even use them in smaller or unusual suburban areas.

This guide tells you all you need to know about buying a rainwater tank for your property.

Types of Rainwater Tanks

There are several materials used to make rainwater tanks. Some of the most common are found here.
Galvinised steel water tank showing the inlet at the top

Metal Water Tanks Melbourne

These tanks are designed using flat rolled or corrugated metal. This metal may be coated or galvanised.

​Usually, metal tanks come with an inner plastic lining, called Aquaplate, that can help increase the longevity of your tank while protecting the quality of the water being stored inside.


Pros
  • Long-life.  These tanks should last 25 to 40 years.
  • UV resistant and suitable for sun-harsh conditions.
  • Fire resistant and suitable for higher BAL rating areas.
  • Come in many sizes and available in very large capacities (e.g. 500,000 litres plus).

Cons
  • Galvanised tanks have a plastic lining that can be damaged from any cleaning or break down over time and require repair.  Stainless steel tanks don’t have this problem or requirement, but they are generally cost prohibitive.
  • Corrosion is more likely in coastal or salty environments.  TIP – make sure rivets and screws used in the construction of the tank are corrosion-resistant.
  • These tanks cannot be placed underground due to corrosion.
  • Less impact resistance – they’ll dent if you hit them hard enough.
  • Usually require concrete foundations, which are more expensive.
Smooth green poly water tank 5000 litres

Polyethylene (a.k.a., plastic) Water Tanks Melbourne

These are another popular option as they are more affordable as some of the other materials, and extremely durable. With these tanks, rust is a non-issue, which means they are a great option for anyone who lives near a source of saltwater.
There are other synthetic materials used with this type of water tank, including geotextile and PVC, which are designed for bladder storage. The bladders are useful for storing water below a floor or deck. Even though this material is tough and durable, it isn’t intended to be used outdoors.
Pros
  • They come in many shapes, sizes and colours.
  • They are relatively light-weight and can be man-handled into position.  They can also be relocated.
  • Resistant to corrosion and 100% rust-proof.  If your water tank is topped up using brackish water from a bore, then poly is a great way to go.
  • Moulded in one piece to reduce weaknesses created by joints.
  • Can take inlet and outlet fittings in any location on the tank.
  • Cheaper than most water tank options.
  • Impact resistance.  Poly can take minor impacts and spring back into shape.
  • Made from food-grade, non-porous poly that keeps water clean and drinkable. All water tanks sold in Australia have to comply with AS/NZS4020:2002.
Cons
  • Have to dispose of them appropriately after their 30 year lifespan.  However, they can be repurposed for raised garden beds and the like.
  • Not fire-proof.  If you are in a high BAL-zone, you may need to factor this into your decision.

Concrete water tank shown partially buried underground

Concrete Water Tanks

These are most commonly used for industrial and agricultural purposes but can be used domestically, most often on smaller acreage. They won’t blow away, melt, burn, or rust. You can purchase these ready-made, or you can have them custom created to meet the specifications of your property and needs.
Pros
  • Can be use above or below-ground.
  • Are incredibly strong, fire-proof and very long-lasting.
  • Has excellent insulation properties keeping the water cool.
  • There are often manholes to give access to the interior of the tank for maintenance, depending on the size of the tank.
Cons
  • For the volume of water stored, concrete tanks are the most expensive tanks to buy.
  • Installation requires heavy lifting equipment.
  • Once you install your concrete water tank, you really cannot move it to another location.
  • Concrete tanks can easily develop cracks and leak.  The reo steel used in the concrete can rust.  Water can reach the steel depending on how well made and compacted the concrete is.  If water reaches the steel, it will rust from the inside out.  Cracks can be repaired, but the rusting reo can’t.  Note that you can get an internal liner or have the interior surface of the tank sealed, but these are additional expenses.
  • The lime from the concrete will leach out into the water to increase the alkalinity of the water.  This increase in pH levels of the water can make it more prone to algae growth. Concrete is also highly porous providing more opportunity for bacteria to take hold.
  • Removal costs are significant.
Two fibreglass rainwater tanks next to a shed

Fiberglass Water Tanks

These water tanks are both chemical and rust resistant and they are uniquely designed to withstand high or low extreme temperatures.

These aren’t the cheapest options available, and they are considered more suitable for installation above-ground.

​There are other types that are able to be installed below-ground. These tanks aren’t as readily available as poly tanks.

Water tank in a Melbourne suburb

What Size Water Tank Should You Buy?

The capacity of the water tank you choose is dependent on the shape and the size of your garden and home and what your water needs are. For example, squat, round tanks are going to fit easily under the deck. A slimline tank will be great for narrow spaces. You should use a bladder storage system or an underflow tank for any limited space area; however, it is much more expensive.
​

Today, there are thousands of options you can choose from. Get it right and you’ll have the right solutions and water supply for a long time.  Get it wrong and you’ll be annoyed every time you use it.. There are some things you can consider to help you find the right water storage tank size for your needs.

Tank Location

How much room you have will be a major determining factor of what type and size tank you should buy.  Look at the total footprint area you have.  This will determine the largest diameter you can get in a tank.  If going between your house and a fence, you may need a slimline tank.  If you have limited yard space you may want to burry your tank under your lawn or driveway.

The closer the tank is to your roof gutters, the less plumbing work there is to do.  If you are retrofitting tanks to your already built house, you’ll need to be mindful where the gutter falls to as this is where all of the water run-off from your roof will go.

The higher the tank outlet is in relation to the point of use, the higher the natural water pressure is.  Depending on what you are using the water for, this may mean you don’t need a pump.
​

In hotter locations, try to put the tank in a shady spot behind buildings or next to trees. This is particularly the case for poly tanks that are more affected by UV over time.
Very large steel water tank in a rural setting

Rainfall & Catchment Area

The higher and more regular the rainfall, the smaller your tank needs to be as it will rain often enough to keep filling your tank.  But if it does rain often, or you have long periods of no rain (typically summer in Melbourne) you’ll need more capacity to see you through.

The smaller your roof area the larger your tank needs to be as it will take more rain to fill your tank and you should capture as much as you can while you can.

Each 1mm of rain = 1 Litre (L) of water per square metre of roof area.  So, a 200m2 roof will capture 200 litres of water per mm of rain.
Melbourne’s average annual rainfall is 530mm, so if you have a 200m2 roof you will catch 530mm x 200 = 106,000 litres of water.  But the trouble is that the rainfall is not evenly distributed over the year.  See Melbourne’s average annual rainfall here http://www.bom.gov.au/climate/averages/tables/cw_086071.shtml

Just as an example, let’s say you worked out that you need 1,000 litres of water a week to keep your garden healthy in summer. 

You know that it may not rain for most of summer, so you’ll need 3 month (12 weeks) of water storage to see you through.  12 weeks x 1000 litres = 12,000 litres. 

​You need a 12,000 litre water tank (of 2 x 6,000 litre tanks).

What is the Main Goal of Collecting Water?

One of the most important things you need to consider is what your long-term needs and goals for your water storage tank actually are. Some of the most common goals for water tanks include:

Saving Money
Do you have the goal of buying a water tank to save money, you must determine the cost to benefit ratio related to installing and maintaining a bigger tank versus a smaller tank? There could be costs related to filling each tank, too. While the initial cost of the larger tank may be higher, it can save you time down the road.  Generally, town water is cheap, but it’s becoming more expensive each year. 

Self-Sufficiency
Do you want to achieve self-sufficiency? If so, you have to make sure you can handle all your home needs and how you are going to use the water. Be sure you are storing your drinking water separate from the water you use for cleaning or your garden.
Keep in mind, the modern water storage tank sizes need to be determined by how often you access the water inside them, and the total amount of water that you will need each time you use the tank. Usually, drinking water isn’t going to go as fast as the garden water; however, this may vary from one household to another. Figure out what your needs are, double this amount, and then select a size that gives you the ability to experience future growth and that fits your established budget.

Also, if water restrictions kick in you may not have the water you need to save your garden.
​

What Are Your Water Needs?
It’s important to carefully consider your water needs when you are selecting a tank, as this is also going to impact the size and shape that you should purchase.  If you have no garden to speak of and only need it for your household, you will need less capacity.  If you have a large garden (particularly veggies) you’ll need a lot more water storage.

Collecting Your Rainwater

The main thing you need to consider when collecting rainwater for your water tank is that you want your water to be clean.
  • Keep your gutters clean.  Doing regular maintenance of your gutters to keep them clear of leaves and other materials.
  • Use a leaf guard.  This is a small wire guard that sits between your gutter outlet and your tank inlet to filter out larger matter life leaves and twigs.
  • Use a first flush device that dumps the first X litres of water off your roof (the water that contains the most contaminants). Make sure your first flush diverter is large enough to take the first millimetre of rainfall from your roof. You get one litre of water per millimetre of water per square metre of roof.  So, a 200 m2 roof will produce 200 litres of water that your first flush system needs to handle.   
  • Use a sieve on your tank entry point for water (at the top of the tank).  This will filter out finer particles to reduce the amount of sludge that will build up in your tank over time.
  • Have your tank outlet a few inches above the base of your tank so it doesn’t pull the heavier particles into your outlet pump.
  • Cleaning your tank.  Every so often, you may need to clean the sludge out of the bottom of your tank using a tank cleaning service with a suction hose that put into your tank through the inlet at the top.  But if you follow many of the points above you may never need to do this.
Typical leaf guard that comes before the water tank inlet at the top
A first flush system that discharges the dirty water

What Size Water Pump Will You Need?

A rainwater tank pump
If you are only planning to use the rainwater for your garden, then you may not need to have a pump, especially if you have a tank that is on a tank stand or if your garden is on a slope that is below the tank level – gravity is the most affordable pumping system available.

However, if you need more pressure than what gravity offers, a pump will be necessary. This is the situation if you are planning to use the water inside of your home with your fixed plumbing system, or with an irrigation system that necessitates normal mains pressure. Essentially, any application where you would usually access the mains pressure is going to have to have a pump. The only situations when this isn’t necessary is if the tank has been installed on a hill close to a building where it is collecting water, and if the point of use is down near the hill by a minimum of a few metres.
​

Even though there are several mains-powered pressure pump options available, your rainwater pump needs to be determined by three main factors: noise, reliability, and application.

For your specific application, you must know the flows and pressures that are required. For example, if you are running a lawn sprinkler and shower at the same time, you will require 15 litres per minute with 140 kPa pressure. If you plan to run a full irrigation system, you may require up to 60 litres per minute with 400 kPa. If you want to run your indoor appliances at the same time, you can work backward from the number of appliances you are trying to run. If you add all these up, you can determine the right flow rate.

The pressure that is needed will be determined by the size and the length of the pipe. The longer the pipe the more frictions that is inside and the higher the pressure will be to deliver the needed flow rate. As a result, it is necessary for you to choose a pipe that is big enough to help minimize any type of frictional losses. Try to stick to pipe that is 25 mm in size or bigger so you never run into issues while you are around the house.

Reliability is determined by a number of factors, including the suitability of the application, the quality of the installation, the construction materials, the water quality, controller, and pump. If you plan to use the pump often, and are dependent on it working well, don’t purchase a cheap unit. However, if the pump that you have isn’t critical to the application, like if you are just watering your lawn, then using a lower-powered pump may be sufficient.

The majority of pumps in use today are external to the actual tank. They have different pipes that run from the tank outlet to the inlet in the pump, and another pipe that runs from the pump outlet to where the water will be used. However, if you choose a submersible pump, they will be submerged completely into the tank; however, the main disadvantage is that there is not as much pre-pump filtering because they are sitting close to the base of the tank in the water that is most polluted. A better option is to fit a float on the pump and let them collect water close to the top of the tank, which is going to significantly improve the quality of the water being gathered and used.

A pressure pump will typically include a pump controller, which is usually just a switch that is pressure-operated; however, there are many electronic models, too, which will turn the pump of and on as required. Try to look for a controller that provides “dry run protection.” Dry running is the fastest way to completely destroy a pump.
​

You must consider the pump’s speed – either single speed or variable speed. The majority of pumps are still considered a single seed unit, with the pump being switched of and on by the controller as the demand requires. This is a type of pump that is virtually always used along with the pressure tank, which offers a reservoir of water that is under pressure. This is going to help reduce the total number of pump starts and will improve overall pump longevity.
In most situations, the single speed pump will work for general purpose use of the water. But if you are going to be using the water for more serious applications, you need a pump that can maintain the pressure levels required with several taps being used at the same time.
If in doubt, ask a plumber or visit your local plumbing supplies store.

How to Install an Above-Ground Water Tank

The most important thing to consider with tank installation is that water is very heavy, so your tank needs a solid and level base.  1 litre of water weighs 1 kilogram.  The water in a 10,000 litre tank weighs 10 tons. A common base is bedding sand on level ground with a border to hold it in.  This is a cheaper option, but the sand can shift over time making the tank tilt.  If your tank is out in the yard well away from any other structures, a few degrees of tilt won’t matter too much.  But if your tank is pretty hard up against your house, a concrete pad to sit it on will make sure it doesn’t tilt into the house.

The best base is level concrete.  It does cost more but it will never shift.  As a rule, the narrower the tank base, the stronger the case for a concrete base.  For example, slimline tanks will move far more easily so would be better on a concrete base.

If you are ready to install an above-ground water tank, you should remember that having a tank full of water isn’t beneficial if you can’t distribute it. There are several additional components of any rainwater system that may have to be installed based on how you plan to use the water.
​

Also, when your tank is brand new, it can cause your rainwater to have a slight taste. For example, if you have a fibreglass or a plastic tank, it may cause your water to have a plastic taste. If you use a galvanised tank, it can create a metallic taste. With concrete, the pH of the rainwater may be increased because of the excess lime that is in the concrete, which can cause a bitter flavour. Any taste that is caused by the tank to your water will usually fade after a while, but if you plan to use the water for drinking, it’s a good idea to dump out the first fill, which will help to flush out the majority of manufacturing residues that may be present. It’s also necessary to use a quality filter, which can help reduce the presence of these unpleasant flavours and tastes.

In Summary

So, in summary, here’s what you must consider when choosing a rainwater tank.
  • Water storage goals – what will you use the water for?
  • Tank capacity – how much water will you use to meet your goals?
  • Tank type – poly, fibreglass, steel or concrete?
  • Tank size/shape – round, square, tall, squat, slimline?
  • Tank location – where will it go and what room (footprint) do you have for it?
  • Water catchment capacity – what is the rainfall for your area and your total roof area?
  • Rainfall pattern – how many weeks/months of no rain do you need to allow for (traditionally summer in Melbourne).
Gerden watering cans sitting on top of a steel water tank in a garden

Are You Ready to Install Rainwater Tanks?

If you are interested in buying a rainwater storage tank, be sure to keep the information here in mind to find the right one for your needs. The information found here will help ensure you get the desired results and that the solutions meet your needs. Don’t underestimate the benefits of finding the right tank – it will pay off and help you achieve your goal. 
​

This guide is brought to you by Water Tanks Melbourne and Slimline Water Tanks Melbourne.
Picture
Suite 5B
8 Eddy Street
​Moonee Ponds VIC 3039
Term & Privacy Policy
  • Home
  • Services
  • About
  • Contact
  • Tank Info
    • Gardening
  • Blog