A tank that is too small can leave a household watching the gauge during a dry spell. A tank that is oversized, poorly sited or matched with the wrong pump can cost more than it needs to and create ongoing maintenance issues. Choosing water tanks is therefore not simply a matter of picking a capacity from a catalogue. It is about building a water supply that works reliably for your property, your rainfall and the way you use water.
For homes, farms, acreage blocks and small commercial sites, stored rainwater can support everyday use, livestock, irrigation, fire preparedness and backup supply. The right system starts with sound planning and finishes with quality components that are suited to Australian conditions.
Start with how the water will be used
The intended use determines nearly every decision that follows. A garden-only tank has different requirements from a tank supplying showers, toilets, laundry and drinking water. Likewise, a farm tank serving stock troughs needs different flow rates and pipework from a system supplying a house and shed.
Estimate daily demand before selecting capacity. Consider the number of people on the property, fixture use, garden size, livestock numbers, irrigation requirements and seasonal changes. A holiday home may have modest demand for much of the year, then high demand over school breaks. A rural property may use far more water during hot, dry periods, precisely when rainfall is less dependable.
Roof catchment is the other side of the calculation. Larger, clean roof areas collect more water, but local rainfall patterns matter just as much as annual totals. Consistent rain through the year calls for a different storage approach than a district with long dry stretches followed by heavy downpours. Good tank sizing accounts for both water coming in and water going out.
Choosing the right capacity for water tanks
There is no single best tank size. The practical choice sits between your available catchment, likely demand, budget, site access and the level of water security you need. Where space and budget allow, additional storage can provide useful protection through dry weather, particularly for properties relying heavily on rainwater.
When comparing capacities, look beyond the tank alone. A larger tank may require a more substantial base, wider site access for delivery and a planned location that allows safe overflow drainage. It may also change pump requirements if the water needs to travel a long distance or climb to elevated buildings.
Four details should be confirmed before ordering:
- the usable roof catchment area and local rainfall pattern
- household, agricultural or commercial water demand
- the level, prepared space available for the tank and delivery vehicle
- intended pump location, pipe runs, power supply and overflow route
For many properties, more than one tank is a sensible option. Multiple tanks can fit around site constraints, provide staged storage expansion and allow one tank to be isolated if cleaning or repairs are required. They can also be linked, provided the pipework and overflow arrangement are designed correctly.
Poly, steel or an existing concrete tank?
Tank material should suit the site, storage volume and service requirements. Poly tanks are a popular option for residential and rural applications because they are durable, corrosion-resistant and available in a wide range of shapes and sizes. They are often straightforward to position where access is suitable, but they still require a properly prepared, level base that supports the full weight of stored water.
Steel and Aquaplate water tanks are well suited to larger storage needs and sites where a round tank provides the best use of available space. Their strength and capacity options make them common on farms, commercial properties and larger households. Quality materials, correct installation and suitable liners are essential for long service life.
Existing concrete tanks should not automatically be replaced. If the structure is sound, concrete tank repairs, cleaning or a new liner may return it to service. The decision depends on cracking, internal condition, contamination risk, access and the cost of restoration compared with new storage. An inspection before committing to a replacement can prevent an expensive assumption.
The base and location matter as much as the tank
Water is heavy. One litre weighs approximately one kilogram, so a 22,500-litre tank holds more than 22 tonnes when full. That load must sit on a stable, level base designed for the tank footprint. An uneven or undersized base can lead to distortion, stress, poor drainage and avoidable damage.
Locate the tank close enough to the roof catchment to keep gutter and pipe runs practical, while allowing room for maintenance, cleaning and safe access to fittings. Avoid placing it where vehicle traffic could strike pipework or where tree branches and leaf litter will create constant contamination. Check that the overflow can discharge away from buildings, footings and neighbouring land without causing erosion.
For bushfire-prone areas, storage placement, fittings and access may need additional consideration. Water intended for firefighting should be planned around the relevant local requirements, not treated as an afterthought once the tank is installed.
Pumps turn stored water into a usable supply
A quality tank will not deliver reliable pressure on its own. The pump must be matched to the application, including the required flow, pressure, pipe size, distance and vertical lift. A small pressure pump may be ideal for a compact home system, while irrigation, stock watering or several buildings may call for a higher-capacity arrangement.
Oversizing a pump can create excessive cycling, noise and unnecessary power use. Undersizing it can result in weak showers, poor irrigation coverage or a pump that struggles when several taps are open. Pressure controllers, pressure tanks, dry-run protection and suitable isolation valves can all improve performance and protect equipment.
If the property has mains water backup, a correctly designed changeover arrangement can maintain supply during a dry period. The setup must protect potable water quality and meet applicable plumbing requirements. This is work for qualified professionals, especially where rainwater and mains water systems connect.
Filtration is about water quality, not just clear water
Rainwater can be an excellent supply when the collection and treatment system is properly managed. Gutters, leaf guards, rain heads, first-flush devices and screened inlets reduce the debris entering the tank. These measures are often more effective and economical than trying to solve contamination after it reaches stored water.
For household use, filtration should reflect the end use and the condition of the catchment. Sediment filtration removes particles that can affect water appearance and wear pumps or fixtures. Carbon filtration can improve taste and odour where appropriate. UV sterilisation is commonly considered where rainwater is used for drinking, as it treats microbiological risks when the water is clear enough for the unit to operate effectively.
No filter can compensate for a neglected tank or contaminated roof. Keep the lid secure, screens intact and roof catchment clear of animal droppings, leaf build-up and other debris. Use food-grade components where water is intended for human consumption, and select equipment that is suitable for the relevant Australian standards and application.
Plan for maintenance from day one
Reliable water storage is maintained water storage. Periodically inspect gutters, inlet screens, overflow screens, lids, taps and pipe connections. Check for sediment build-up, signs of algae, damaged mesh, leaks or unusual pump behaviour. A sudden change in pump cycling or water pressure often points to an issue worth addressing early.
Tank cleaning intervals depend on roof condition, surrounding vegetation, water use and the amount of sediment entering the system. Cleaning is also a good opportunity to inspect liners, internal fittings and the general tank condition. On larger or older systems, professional cleaning and maintenance can make the job safer and provide a clearer picture of what needs attention.
North Coast Water Tanks can help property owners bring tank storage, pumps, filtration, accessories and practical support into one coordinated system. That matters when a new tank is only one part of a larger water supply plan.
A well-chosen tank should make life on the property easier, not add another system to worry about. Start with honest demand figures, allow for dry periods, prepare the site properly and choose components that can be serviced for years to come. That approach gives your stored water the best chance of being there when you need it.