Maintaining a Garden with Greywater

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Using greywater in cleaning the exterior of houses, such as driveways, patios and gutters are great ways to conserve water. You can also use greywater to wash the exterior of vehicles such as cars, motorcycles and bikes including their wheels. Greywater comes from household wasterwater such as the kitchen sinks, vanity sinks, tubs, showers, dishwashers and clothes washers. Typically, 50-80% of household wastewater is greywater, the rest are from the toilets or contaminated greywater. Toilet wasterwater and contaminated greywater are known as blackwater, which are not safe for watering plants or cleaning outdoors. Contaminated greywater are those that come from kitchen sinks water laden with food solids and laundry water that has been used to wash diapers or anything contaminated with dirt and harmful pathogens.

Collection Methods

Greywater collection or irrigation systems is not always simple to create and, depending on the design, can be quite expensive. In some places, you would need a permit to have one installed. To minimize the expense, it is important to assess your overall watering needs. If you only need used or greywater for cleaning outdoors, then there may not need an elaborate design; however, if you need to water plants and grow food, you would need a system that can filter the bacteria. There are also some requirements to meet, such as enough space and soil. Some of the common collection methods include drain to mulch basin, branched drain, constructed wetland and solar greywater greenhouse.

Drain to Mulch Basin

This type of greywater irrigation is the simplest method. It does not need a filter, pump or surge tank. It uses very little pipe and does not require a lot of maintenance. It is the cheapest and easiest to build– anyone can build it. Furthermore, it has a low failure rate and can last for a long time. It is a simple connection from the household drain, commonly the kitchen sinks or bathroom sinks where a small piece of pipe connects to the drain and to the mulch basin. The mulch basin should contain a mixture of topsoil and mulch.

Branched Drain

This method is similar to the first one as far as method; however, it is more elaborate because it involves multiple drains connected to several mulch basins. This means more materials would be required in order to disperse greywater to several locations.

Constructed Wetland

This method is ideal for wet climates. It is good where soil perk is low and space is restricted. This method covers a larger area and collects larger volumes before reusing. Larger uptake of wetland plants can reduce the reuse efficiency of this method; therefore, it is not advisable to use it in dry climates. Construction p[ermit may be required and involves adding filters to further clean the greywater from possible unseen contaminants.

Solar Greywater Greenhouse

This is an expensive option among the methods mentioned here; however, it provides the highest ecological net grain for cold climates, provides year-round treatment of greywater, excellent for food production and it can also help heat the house by conserving the heat in greywater.

Before making deciding on which method you should use, consider the location, greywater sources, irrigation needs (small, medium, large), climate and water availability.


Greywater collection and irrigation can help the environment by reducing freshwater use. Greywater recycling for irrigation replenishes groundwater to help in the water cycles. It can also help in not overloading the septic system by diverting the water to the collection system, and then to the soil. In places where water is scarce, greywater irrigation can help in watering plants and encouraging plant growths. It also helps in soil fertility, by the breakdown of bacteria by the soil.