Suppose you have a lovely garden: a vegetable garden or a permaculture food forest for example. We all know that it takes quite a lot of water to keep the plants happy. Perennials and trees might take care of their water supply due to their wonderful deep roots, but new plants, vegetables, and certain herbs and flowers might need a little help.

Of course, you can just turn on the water tap, but what if you prefer not to do so or are not able to? Then you can collect rainwater and use that. In hot climates, this will not be enough to use the whole year round though.

Offgridders (why is this word not in Webster’s dictionary) know: you can use your gray water to irrigate your land. In this article, we will explain what gray water is, and show you two ways you can employ to irrigate your garden with gray water.

What is gray water?

Gray water is the used water that leaves your sink in the kitchen, your washing machine, and your shower or bath. If you do not use chemical soap, you can filter this used water and use it to irrigate your garden.

You can also use gray water for flushing your toilet for example – but that is another topic. In this article, we will stick to using gray water for irrigating your garden.

Why would you want to reuse gray water?

There are several reasons for wanting to re-use the gray water:

• Water may be scarce in your region.
• You do not wish to waste all that gray usable water.
• You prefer not to use a lot of tap water to irrigate your land because it places a burden on the communal water supply.
• You do not want to further pollute our oceans. Normally, the gray water will be mixed with black (toilet) water in the sewage canals. This gray/black water eventually spills out into our oceans. The oceans become polluted by all of this gray and black water. By using gray water you are diminishing the pollution of the oceans.
• It is cheaper to use gray water instead of tap water.
• You like to be autonomous and live off the grid, taking care of your resources.
• You can not rely on the tap water system in your region.

Setting up a gray water system with water tanks

Stage one

First, you need to lead the water from your kitchen and/or shower through a mesh. Here any debris from dirty dishes, and hairs from showering, for example, are caught.

Stage two

Now you can lead the water through one or two grease traps. These can catch any oil or fat that may be in the water, for example from cooking and using soap. This way you prevent the pipes from clogging further on in your gray water filtering system.

Stage three

After this, the water flows, either through gravity downwards, or upwards using a pump, to the first tank. This first tank is filled with large pebbles and plants on top. This tank filters out the bigger particles in the water.

The big pebbles filter big parts of dirt because the bigger parts of dirt will be stuck between the stones.

Each plant filters water via its roots. The bigger the leaves, the more water a plant absorbs and thus filters. There are specific plant varieties that are suitable for filtering water. The varieties that you need depend on your specific region and the climate.

You can make your tank with ferro cement: this is an easy and cheap way of making a tank. You can also use cement or even plastic. Plastic can be the best choice for people that live in remote areas up in the mountains and who do not have a car.

Stage four

Now the water can flow to your second water tank. This tank has smaller pebbles in it, and again it has large-leafed plants whose roots filter the water. The small pebbles filter out the smaller particles in the water.

Stage five

The water now flows to the third tank, filled with sand and yet more large-leafed plants. The sand filters out the smallest particles of dirt in the water.

Stage six

Finally, the water reaches a reservoir. From here Irrigation pipes lead to your plants and fruit trees, yay!

Setting up a gray water system by digging holes

Here you can read how to make a very simple system that can filter your gray water and that will provide you with water to irrigate your land. This system is suitable for those gardening in a tropical climate, and on land with differences in height. It is a system that can be used by people with little means.

Stage one

You can lead the gray water via a drain to your land that is sloping downwards.

Stage two

Here you dig three holes next to each other, on the slope. Let the drain go to the first, highest hole. The force of gravity will lead the water from one hole next to the other two.

You let the gray water go directly to the holes and let them fill up.

Stage three

You cover the holes with plant debris/mulch. This way there will be no mosquitos or flies.

Stage four

Around the holes, you plant banana plants or other plants that drink a lot of water. The roots of the banana plants will grow around and under the dug-out holes. They will keep on filtering the water in the holes.

Final thoughts

It can take some effort to create a gray water filtering system, but what a joy to reuse all of that gray water! Nothing is wasted, and your plants will be happy.

We hope that you will be setting up your water filtering system and that it will bring abundance to your garden!