Grey water: what is it?

Grey water is leftover water from household activities like dishwashing, laundry, and bathing. It’s an interesting element of our daily lives that we usually don’t pay much attention to - when we wash our dishes, do laundry, or take a shower, where does this water go? Well, the answer is always - somewhere - but varies for every living situation and location. Usually, it means down the drain and washed into a local waterway such as a lake, river, or ocean.

This is a problem because many times the water that we use for these kinds of activities takes hundreds (to thousands) of years to get beneath the soils surface at that level. By extracting this water in such large quantities and at such a fast pace, we don’t allow these water sources to replenish. On a large scale, this has devastating effects for local watersheds and is one of the major issues currently plaguing many parts of the earth as we speak (like the ongoing California floods).

While the "blackwater" from our toilets needs a considerable amount of treatment before it can go anywhere, grey water is a different story. It's relatively clean and nutrient-dense, and with a little bit of know-how, it can be given a second life in our gardens. Instead of just letting it slip away into the sewage system, we can redirect it to where it can bring life and food back to us. By slowing down its journey from our homes into the soil we're not just saving water, but turning what would be waste into something valuable for our landscapes.

How a grey garden works

Start by envisioning yourself at the sink, washing your dishes. This water moves down the drain, and instead of being directed towards plumbing that pushes it to a sewage line or septic system, it’s instead diverted out of the house and into a grey water garden. The size and details of grey water gardens vary greatly from site to site, but most commonly they are kept near the house for ease of plumbing and gravity.

This water then goes through a series of filtration mechanisms, where it gets a good clean-up. The first filtration system typically aims to remove larger particles and impurities like food bits, hair, and biodegradable soap residue. The most common items used in this stage are coarse physical filters like bark pieces and gravel, which trap larger debris. Incorporating worms at this stage is very common. The second stage might involve a finer material like sand, to further reduce particles even smaller.

This is when the magic of plants comes into play, as some reeds, grasses, canna lilies, and irises can filter water through their root systems. These plants are commonly found in bog like landscapes and can be incorporated into one or more of the filtration systems in the garden, ensuring that by the time it makes it to the garden it is practically clear.

Finally, this clear water makes it to where we want it to go - the garden! At this stage there is a ton of room for creativity in the design and all depends on what you want to grow. The water can be used to grow food in wicking beds, for fruit trees and bushes, or for a low-maintenance pollinator garden.

See below two great videos explaining the in’s and out’s of a grey water garden:

Things to know about grey-water gardens: The Do’s & Don’ts

• Do use biodegradable solutions: you should always use biodegradable and natural cleaning solutions to ensure the greywater is safe for garden use. These solutions reduce the risk of introducing harmful substances into the ecosystem and plants.

• Don't use harmful chemicals: avoid using grey water that contains any type of bleach, chemical or pesticide.

• Don't store greywater for long periods: storing grey water for more than 24 hours can lead to bacterial growth and unpleasant odors, rendering it unsuitable for garden use. Grey water systems should be designed to move water quickly, without access to oxygen.

• Don’t allow pooling: It's important to prevent grey water from pooling or running off to avoid creating breeding grounds for pests and the risk of soil and water contamination.

• Do maintain your system: regular maintenance of your grey water system is key to ensuring it continues to work well and ensures safety. This includes checking for blockages, leaks, and the overall functioning of the system.

• Do consider soil permeability: make sure that the soil in your garden is permeable enough to effectively absorb grey water without leading to waterlogging. This is vital for the health of plant roots and overall soil quality.

• Do integrate grey water into garden design: consider your overall goals, placement of plants, types of plants, and the layout to facilitate optimal watering.

• Do monitor plant response: observe and interact with how your plants respond to grey water irrigation throughout the seasons and make changes as necessary.

Grey water is practically liquid gold

Installing a grey water garden is one of the best ways to level up your garden skills and cycle your own waste back into the system. By doing so, you not only contribute to a more sustainable ecosystem but also reduce your dependency on the municipal water supply, leading to savings on utility bills and a more resilient garden. This is a practical approach in permaculture that benefits both your wallet and the environment. Embracing this also has the potential to transform our perspective on waste, turning it into a valuable resource that nurtures gardens and, more broadly, our earth.