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[Voiceover]: We live on our world's driest inhabited continent. And in some parts of WA, it's getting even drier due to climate change.

A big part of our role is to make sure there's enough drinking water for WA in the future.

We're always exploring new water innovations and sources, and encouraging households, businesses, and councils to save water.

Given we're looking to the future it makes sense to do something that is about as high tech as water can get.

Introducing the Advanced Water Recycling Plant. In 2004, we started looking at ways to make use of the millions of litres of treated wastewater leaving our treatment facilities.

[Josh Hogg]: We already use treated wastewater to irrigate local parks, ovals, and green spaces.

In fact, for our regional areas this is where most of the treated wastewater ends up.

Where irrigation isn't an option, the treated wastewater flows out to the ocean. Ocean outfall, as we call it, used to happen to most of our treated wastewater in the Perth Metro area, but we knew there was a much more productive way to use this water, as a drinking water source.

Back in 2012, we completed a three-year trial that showed we could further treat wastewater to drinking water standards.

The trial showed this could be done effectively and, with community support, pave the way for the same process to be undertaken on a much larger scale.

And that is the story behind where I am standing now, a facility where we further treat wastewater to drinking water standards.

We then inject this recycled water into our underground aquifers. We call this process groundwater replenishment.

Now, the concept of drinking what was once wastewater can be pretty hard for some people to stomach. After all, most of it originally came from our sinks, showers and toilets.

For people who find the idea of drinking recycled water a bit yuck, here's a cool fact. The recycled water we recharge to our aquifers is actually cleaner than the water that's already down there.

Even then the recycled water we've injected stays in the underground aquifers for years before it eventually finds its way to our taps again.

I did drop a word in there that you may not be one hundred per cent familiar with, aquifer. What is that?

When rain hits the ground, some droplets evaporate straight away or run off to streams or rivers. The remaining water slowly filters into the gaps in sandy soils or rocks to become groundwater. Shallow and confined aquifers are where this groundwater is stored.

In Perth, we have a vast groundwater system that contributes to our drinking water supply. But climate change and inconsistent rainfall means less water is going into our rivers, dams and, in some areas, groundwater stores. That's why we need to diversify our water sources that don't rely on rainfall.

Enter the Advanced Water Recycling Plant. So, we've got a rough idea of the groundwater replenishment process, but how exactly does it work? This is a balance tank where millions of litres of treated wastewater arrive from our neighbours at the water resource recovery facility. We store the incoming treated wastewater in this tank to maintain a consistent flow through the plant. From here, the treated wastewater goes through three further treatment stages.

Ultrafiltration, reverse osmosis and ultraviolet disinfection.

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These are the ultrafiltration cylinders. There's a lot of them. We're able to push a lot of water through here, about 1,600 litres every second. That comes to one Olympic-sized  swimming pool of water filtered every 26 minutes.

Each vertical unit looks like this inside. There are about 10,000 of these filtration tubes in each cylinder. Although we can't see them, each tube has tiny holes that are about 1/300 the width of a human hair. They're basically thousands of super thin straws. The water is pushed through the tubes which remove the larger molecules.

If you were to take out all the tiny tubes and lay them end to end, they would almost stretch around the equator of the Earth, about 39,000 kilometres. Next, is reverse osmosis.

A similar process used in seawater desalination. High powered pumps push water under pressure through these membranes.

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It takes a lot of pressure to push the water molecules through, around 1,000 kilopascals.

With that amount of pressure, you could push one litre of water 100 metres into the air. They differ to the ultrafiltration membranes. Instead of straws, they're more like large lasagne sheets tightly wound, and with microscopic holes that are 100 times smaller than those in the ultrafiltration units.

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Here we are, at the last step of the treatment process, ultraviolet disinfection.

Whilst not noisy itself, it shares this room with the reverse osmosis feed pumps which are making all that noise.

It all happens in a flash. The ultraviolet or UV light acts as a final safeguard, deactivating any microorganisms that might be left.

This is one of the many sample panels around the plant. They measure different aspects of water quality, such as pH and conductivity.

If the water doesn't meet the standard at a particular checkpoint, it triggers an alert for us to take action which may mean diverting the water until the required water quality is achieved.

That's very rare. Most of the time it's all smooth sailing here in the plant central control room.

Once the water has been through all three stages it is ready to be pumped underground via a recharge bore.

At Beenyup, the recycled water is injected into two separate aquifers. Both aquifers are directly below the plant. One is called the Leederville aquifer and the deeper aquifer, the Yarragadee.

Water is also transferred 13 kilometres away to Wanneroo and Neerabup for injection.

To get the recycled water back underground we pump it through these recharge bores, which go down between 200 and 1,200 metres. The bottom section of the bores have small holes that evenly distribute the water into the aquifer. We regularly test and monitor the recycled water. This is one of our monitoring bores. We collect samples from here to send to laboratories for testing. We also monitor the direction and speed at which the water is travelling. Our research has shown the water moves pretty slowly in the ground. During our three-year trial from 2010 to 2012, it moved about 200 metres.

We can tell the difference between existing ground water and recycled water by the temperature and the level of salinity, that's how much salt there is. Over time the existing water will mix with the recycled water and become pretty much indistinguishable.

As we continue to put more recycled water back in the ground it might move more quickly but it will still take years for it to reach a bore where we can take it out and add it to our drinking water. I know what you're thinking. You just can't believe that this water has come from your sink, shower or toilet. Before the recycled water is pumped into the aquifer, it is already safe to drink. When it's drawn back out of the ground years later, the water goes through another treatment process at our groundwater treatment plants. With our environment continuing to change, is this the way of the future? You bet.

We are so certain we've doubled the size and capacity of our Advanced Water Recycling Plant here in Craigie. But this will never replace good efficient water use, something which we can all start right away.

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To learn more about our water world, visit our website.