What Is Greywater?

Think about the last time you had a shower. In the ten minutes you took to wash off the day, around 160 litres of water went down the drain. Water that, with a little help, could have been used again. The same thing happens every time you wash your hands, rinse the dishes, or put a load through the washing machine. That’s water you’ve already paid for, disappearing before it’s had the chance to earn its way. 

That dirty-ish water is what’s known as ‘greywater’. Greywater is the wastewater from everyday household activities like showering and washing clothes. And most households in New Zealand aren’t using it to its full potential. 

Greywater vs Blackwater

Greywater is the water that comes from showers, basins, baths, and laundry. You’ve used it once, but it’s still relatively clean. So close to being clean, in fact, that with some clever filtration, it can be reused for other things, like watering your garden.

Blackwater, however, is what leaves your toilet - and that’s not something you can reuse at home. 

For the purposes of this article, greywater also includes the water from your kitchen sink. It’s worth knowing, though, that dishwasher/kitchen sink water takes a little more effort to reuse. Since oils and food scraps need to be removed before the water is safe to filter, you need to run it through a grease trap first, but more on that later. 

Why Greywater Matters in New Zealand

In New Zealand, we’re incredibly lucky to have easy access to beautiful, clean water, and man, are we making the most of it! The average Kiwi uses 227 litres of water per day in their daily lives. Across a family of four, that works out to more than 330,000 litres a year. While 37% of that is blackwater, the other 63% is water that could be reused, with some great benefits. 

1. More Environmentally Friendly
   Every drop of greywater you reuse is a drop of fresh water that stays in the reservoir, river, or tank. Instead of paying for it once and sending it away, you’re putting it to work in your own backyard. That means greener gardens for you and less pressure on the environment.
   
   
2. More Self-Sufficient
   Greywater reuse suits how many New Zealanders want to live. Households on tanks know how quickly reserves can run low in summer. Off-grid homes need to stretch every litre further. Even in town, council restrictions often limit how and when gardens can be watered. Having your own recycling system means you have more control over your water usage and can keep using it responsibly without the stress of running out.
   
   
3. More Affordable
   Using water twice makes financial sense. If you’re on mains, it helps cut down the cost of every bill. For tank households, it reduces the need for costly refills when levels run low. And for bore users, it means less wastewater entering your septic system, lowering the risk of overloading it and saving on maintenance. However you access your water, reusing greywater ensures you get more value from every drop.

What Can Greywater Be Used For?

Filtered greywater is great for your garden and can be used for irrigating lawns, trees, shrubs, and flower beds. It’s not suitable for your veggie patch or fruit trees, because even filtered water can contain small traces of bacteria, but anything that isn’t going to end up in your mouth is fair game. 

A lot of families use it to stop their lawns getting crunchy over summer, when the kids are spending more time playing outdoors. It can also be used to keep established or newly planted trees healthier, with steady irrigation that doesn’t rely on an expensive mains supply.

Simple Systems for Greywater Use

While the idea of recycling water might sound complicated, modern systems are built to make it simple. WaterMate is a compact unit designed for Kiwi homes. It filters out lint, hair, and soap residue using layers of washable mats, ready to put through a drip irrigation system in the garden.

The unit sits outdoors, connects directly to existing household pipes, and is straightforward enough to install yourself. Even maintenance is straightforward, as the filters are designed to be washed and reused. Replacement filters are available too, but most households just give the mats a quick rinse every few months. Minimum effort, maximum reward.

Ready To Reuse Your Greywater?

Greywater is a free resource hiding in plain sight. By reusing it, your household can cut waste, save money, and keep your garden looking great year-round. With a simple system like WaterMate, it’s easy to make every drop count, turning water you once lost into water that works for you twice.

WaterMate is proudly supported and distributed by Allflow, a New Zealand company with more than 30 years of experience in pumps, filtration, and water management.