You can reduce wastage of water by finding ways to collect and reuse water within your house. Most homes use clean, potable water for everything, including flushing the toilet, which doesn't need potable water. Reducing usage of clean water isn't only good for your water bills, it's also good for the environment. In addition, you can comfortably water your garden during droughts and decrease the load on your septic systems/infrastructure, giving you longer service life.

Definition of terms

  • Greywater – this is waste water from non-toilet uses such as cleaning and bathing

  • Blackwater – waste waster that is mixed with toilet waste. Water from dishwashers and kitchen cleaning is considered blackwater due to possible contamination by grease and pathogens

Greywater can be safely reused for gardening, washing clothes and toilet flushing with appropriate treatment and by taking precautions as described below.

1. Does a treatment system make sense for you?

The major consideration if you want to reuse greywater is the cost implications of installing the treatment system. Whether or not this is a worthwhile investment for you depends on the scarcity/availability of clean, piped water, cost of clean water, whether you have some treatment system or you'd start at the beginning, how long you'll stay in the house and the type of system you want to install.

To make the most of the treatment system, consider your usage capacity, as operating and maintenance requirements/costs differ with various systems. In addition, if you move around, you'll want a system that can survive sporadic usage.

2. How to improve greywater quality

Your choice of treatment system will largely determine the water quality you get. However, you can reduce the load on your treatment system by implementing a few behavioural modifications in your house. For example:

  • Reduce usage of shampoos, detergents or soaps with high sodium and phosphate content

  • Introduce lint filters in your drains and ensure they are cleaned and replaced when needed

  • Reduce usage of harsh cleaning agents, opting for natural products where possible; for instance, you can unclog a drain using hot water, vinegar and bicarbonate of soda instead of turning to Borax

  • Take care not to dispose of harsh/toxic chemicals like pesticides down the sink. Talk to your garbage collection service or local sewage authority about hazardous chemical collection points

3. Do's and don'ts of gardening with greywater

The above measures will ensure you have environmentally safe water to use both indoors and outdoors. However, the following are some precautions to remember for best results in your garden.

Simple greywater treatment may not guarantee complete removal of disease-causing pathogens or toxic chemicals. Therefore, do not use greywater to water vegetables that are eaten raw.

Overwatering may harm your garden: too much water can leach off nutrients from the soil, cause waterlogging and acidity that hinders plant growth.

You can store treated and disinfected greywater for use during drought seasons by investing in storage tanks that should be separate from your rainwater collection tanks. If storage isn't possible, you can halt greywater treatment until the dry season comes around. If you have more questions about waste water systems, contact a septic service near you.