Easy Gray Water Harvesting Techniques

One of the defining aspects of permaculture which contrasts so radically from our industrial ways of dealing with the land is in how we deal with water. Our modern-day society most often simply looks at water as a resource that magically appears from faucets. Very few people have any understanding of where their household water comes from, and the amount of energy that is needed in order to pump that water sometimes hundreds of miles into their homes.

In regards to the water that we use in our home, we similarly have absolutely no idea where that water eventually goes after it is flushed down the drains of our sinks, showers, and washing machines. As long as our waste water doesn´t cause us any sort of discomfort, then most of us are more than happy to adopt the “out of sight, out of mind” mentality; allowing someone else to deal with the problems related to our waste.

What is Gray Water?

In most homes today, the wastewater that goes down our drains can be divided into two types: gray water and black water. Gray water is the water that comes from our sinks, washing machines, showers, and other water sources that do not contain human feces or urine. This waste, then, simply contains soap residues, dirt, and other harmless debris that is perfectly suitable to be reused in some other way.

On average, each person uses somewhere between 25 and 45 gallons of gray water per day. This includes the showers that you take, the water you use to wash the dishes and your clothes, and every other time you turn on a faucet in your home for something other than flushing the toilet. This can add up to more than a thousand gallons of water each month.

Somewhat ironically, the water we use to irrigate our garden, flower beds, or fruit trees around our homes comes pumped in from hundreds of miles away while the perfectly suitable gray water from our homes could be used for those irrigation purposes. While there are dozens of different practices and designs to reuse your gray water, below we will look at two simple designs for gray water recycling that can easily be implemented to allow for a greater cycling of energy within your home.

Direct Plumbing to Mulched Basins Around Fruit Trees

When it comes to recycling and reusing gray water, simplicity is the name of the game. Complex systems with several parts only invite disaster. While gray water in itself is pathogen free and actually holds vital plant nutrients in the form of phosphate-rich soap residues when it become stagnant within in a recycling system it can quickly become a breeding ground for dangerous pathogens and bacteria. For that reason, you should never store gray water in any sort of tank before sending it to some other place for irrigation.

One simple way to recycle your gray water for irrigation purposes is by redesigning your plumbing system for simplicity and directness. A simple hose can be connected to your washing machine, kitchen sink, or even your shower drain and be directed to nearby fruit trees that you plant around your home.

Around each fruit tree, dig a small, sunken basin and then fill in that basin with a thick layer of mulch. The gray water hose (or set of hoses if you have several trees that need watering) can be led to these basins wherein they will water the trees and add needed phosphates to stimulate tree growth. The thick layer of mulch will ensure that the water gets “sucked up” by the surrounding soil without any possibility of pooling or stagnation. Ideally, you would direct these hoses towards trees that are downhill from your house so as to be able to take advantage of gravity to move the water.

One of the advantages of this system is that hoses are easy to move and this system can thus irrigate several trees. Even in desert climates with very little average annual rainwater, you can essentially create a mini-oasis around your home by recycling the gray water that flows through your house for irrigation purposes.

Sink to Toilet Gray Water Recycling

For people who live in urban areas or high rises apartment buildings, there are still ways that you can reuse your gray water for other purposes. By redesigning your bathroom to place the bathroom sink above your toilet, you can then gravity feed the gray water from your sink into the toilet flush tank. Instead of flushing your toilet with clean, drinking water, then, you are using gray water to create your black water.

This simple gray water recycling solution will save thousands of gallons of water each year from passing through your home. If every household did this simple trick, the water savings would amount to millions of gallons each week.

Recycling gray water is an essential part of any permaculture design. If you are designing from scratch, consider carefully where to place your home so as to best be able to utilize gravity for irrigation purposes. Also, by calculating how much gray water your household potentially creates, you can plan your next trip to the nursery to purchase the future oasis that will adorn your home and be irrigated by nothing more than your shower water.

Tobias Roberts

After working in the development industry for over a decade, Tobias decided it was time to stop advising Central American farmers how to do things if he didn´t have a piece of land to live coherently with what he taught. Together with his family he runs a small agro-forestry farm, tourism cooperative, and natural building collective in the mountains of El Salvador.

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