21 March 2022

Single Large Tank
vs Multiple Small Ones

Which is better: one large rainwater tank or multiple small ones? What are the pros and cons of each option? And how does it affect function, practicality, and ongoing maintenance? Does either option offer a price advantage?

Water Tanks


Which is better: one large rainwater tank or multiple small ones? What are the pros and cons of each option? And how does it affect function, practicality, and ongoing maintenance? Does either option offer a price advantage?

If you’ve been asking yourself one of or all these questions, that’s great! A water harvesting system is a valuable investment, and you need to make sure you get it right, first time round. And you want to get the best bang for your buck, too!

Of course, both options have for’s and against’s, so let’s zoom in and have a quick look at a few of the factors which might influence your decision:

Cons of Multiple Tanks

Available Space

One of the first things to consider is your available space. Obviously, several smaller tanks will take up a greater total area, but one large tank will have a bigger diameter and therefore have a bigger single footprint.

The shape of the available space might be what governs your decision. For example, if you just have a narrow space between your home and your path, a large tank simply won’t fit, so you’ll need to install several smaller ones, perhaps in the slimline design.


It’s not rocket science: installing multiple small tanks will most likely cost you more than installing one large one, because some things about the process don’t change, regardless of the size of the tank. Whether you purchase a 500Ltr corrugated poly water tank or a 2100Ltr corrugated poly water tank, the manufacturing and delivery processes are similar and the only thing that varies is the quantity of raw material needed.

So, if price is your main consideration, one single tank is almost certainly going to be your best option.


More tanks = more maintenance; now that’s really stating the obvious!

While a lot of folks seem to get their tanks installed then forget about them until something goes wrong, a regular maintenance schedule is important and can end up saving you a pretty penny in the long run.

More tanks will mean checking more pipework, cleaning out more leaf strainers and possibly maintaining more pumps. However, on the topic of maintenance, it’s not all doom and gloom - there are a few maintenance advantages with more than one tank, and they’re listed below.

Pipework & Plumbing

The more tanks you install, the more pipework and plumbing you’ll have to install too, which will add to the initial cost outlay. And of course, the more pipework you have, the greater the chances of plumbing issues - blocked pipes, broken pipes, leaking pipes… and anything else that can happen to pipes!

Pros of Multiple Tanks

Lower Contamination Risk

From time to time, contamination of tank water happens, but if you haven’t got all your water in one tank, this issue is a lot easier to manage.

For example, if an animal or bird dies and gets lodged in your gutter, the water that runs into you tank could be fouled – if your water is stored in multiple tanks you can identify the problem tank, isolate, drain, and clean it, without losing all of your stored water!

Multiple Water Sources

Having several smaller tanks can allow you to maximize your water harvesting and storage capacity by storing water from different sources, for example: roof water and bore water. Different tanks can be used to store different types of water, without any risk of cross contamination.

Maintenance Advantages

Yes, when it comes to maintenance, there are a few advantages of several tanks too! Remember that old saying about not ‘putting all your eggs in one basket?’ It’s the same when it comes to water storage!

If damage occurs to one of the tanks or the pipework of one of the tanks, this can generally be repaired without having to touch the other tanks.

For example, let’s say in a rural setting a stray bullet penetrates one tank and it starts leaking. With multiple tanks, you have the option to isolate the damaged tank, drain it, and have it repaired without having to sacrifice all of your water storage.

Minimize Visual Impact

In some circumstances, large tanks can be visually unappealing, so a few smaller tanks placed around your property might be your ticket to maximum water storage with minimum visual impact.

It’s also much easier to blend smaller tanks into your landscaping plans - screens, low hedges and freestanding walls are all great ways to create a visual barrier and hide your water tank.

What Fittings Will be Supplied with my Rainwater Tank?

Each Orion poly rainwater tank is supplied with a leaf strainer, leaf strainer cover, overflow provision, two outlets, a valve and even a roll of thread tape to make your connections watertight!

Is my Tank Base Important?

Very - we can’t put enough emphasis on having an excellent tank base in place, regardless of the quantity or size of the tanks you plan to install!

When your poly rainwater tanks are full, they’ll be very heavy, so your tank base must be stable enough to sustain that kind of pressure long term.

It must be level, clean and constructed from a material which will not wash out during heavy rain.

We highly recommend preparing a base of finely crushed rock for a few reasons:

  • It drains well
  • It can be successfully levelled without compacting too much
  • It’s economical
  • Looks great

How Much Will My Tanks Cost?

This question is a common one, and we’re glad you asked. Our popular 22,000L size retails for around $ 3500 inc GST. Another popular tank in the smaller sizes is our 2100L low profile tank which retails for around $1000 inc GST.

For more information and exact pricing on our poly tanks, give us a quick call on 1800 752 784 or send us a message here and we’ll be more than happy to discuss costs with you.

Can I Get My Tanks Delivered?

Yes - we’re sticklers for good ‘ole fashioned service, which means going the extra mile to deliver our tanks to site (and that means as close as we can to where you want them, not just to your property gate)!

The team at Orion Australia has been manufacturing poly water tanks for 23 years and we’re as focussed as ever on delivering water storage solutions that really work.

Do you want some more information on poly rainwater tanks or have a question about the best option for your water storage? Call us today on 1800 752 784 or send us an email here. We’re looking forward to hearing from you!