Friday, September 12, 2014

Simple Household Greywater Systems

By Wong Ee Lynn
< />

The call for water conservation and wise use and management of water is now more urgent than ever, especially taking into consideration the recurring water crisis in Selangor. In the past, homeowners were often urged to collect and harvest rainwater for household use. However, deforestation has led to reduced rainfall and we are not able to collect rainwater as frequently as we used to.

Many MNS members have expressed an interest in installing greywater systems and reusing greywater. 

Greywater is water from non-plumbing systems such as hand basins, showers, baths and washing machines. It is safe for use in the garden and for flushing toilets with. It should never include water from toilets, kitchen sinks or washing diapers, as these often harbour pathogens. Greywater should never be used on fruits, vegetables and anything you plan to eat.

Most homeowners and building occupants are deterred by the high cost involved in installing greywater systems. The greywater tank system in the picture below, for example, involves quite sophisticated plumbing and pipes and takes up a significant amount of space. 

A greywater tank at the Eats, Shoots and Roots edible garden premises. 

Even simple retrofit systems such as the Toilet Lid Sink in the picture below are not easily available in Malaysia or within the economic means of the people who need it the most to keep their utility bills down.
A toilet lid sink, by SinkPositive
(Image credits:

What can you do to collect and reuse greywater, if you are renting, living in a small space, living in shared accommodation or simply not inclined to install a complex plumbing system or purchase expensive equipment? Here are some tried and tested tips which may seem inconvenient in the beginning when you first implement it, but will soon become second nature, just like sorting your recyclables and taking your reusable shopping bag with you when you leave the house:


1. Use phosphate-free and biodegradable soap, shampoo, detergents and household cleaning solutions whenever possible. White vinegar is an excellent cleaning agent for glass surfaces and mirrors, for example. This is to ensure that the water collected will pose less harm to the environment and to human and animal health when used.

2. If you have a wide and sturdy tub, you can stand in it while showering and let the water collect. The advantage of this is that there is usually a very short distance between the shower and the toilet, so the greywater collected can then conveniently be used for flushing the toilet with. 

3. For general household cleaning tasks such as cleaning the windows, mopping the floor and wiping down tables and furniture surfaces, let the water from cleaning and rinsing collect in a basin and then pour it into a bucket or pail that can then be put in the bathroom or outdoor areas for reuse. You can also collect water directly into a bucket or pail by washing and rinsing directly from a standing tap or hose. To filter out hair, lint and other dirt, you might want to put a piece of fine wire mesh, mosquito screen or an old piece of muslin, cheesecloth or light bedsheet over the opening of the bucket. Use pegs or clips to hold the cloth or screen in place over the opening of the bucket. This way, the piece of screen or cloth acts as a sieve to filter out dirt from the greywater.

4. Some items such as delicate items of clothing, shoes and rugs may need to be handwashed. Pour away the water used for soaking these items, as the water in the earliest stage is likely to be dirty and contaminated. Collect the water from the subsequent rounds of washing and rinsing for reuse in the bathroom or garden. 


1. It is safe to use greywater on trees, ornamental plants and non-edible plants. There is some degree of risk to watering vegetables and herbs with greywater that comes from the bathroom and kitchen. If you do insist on using greywater on edible plants, pour the water into the soil / at the plants' roots, and not all over the leaves and edible parts of the plants. 

2. The average person flushes the toilet 5 times a day. Toilets make up 31% of household water consumption. If you were to place a greywater bucket and scoop by the toilet and encourage those who use the toilet to flush using greywater, you can potentially save over 70 litres of water per person per day. Ensure that the greywater is free of grease, lint and dirt that may clog up the plumbing. The last person to use the toilet that night should flush it with the water in the cistern to 'rinse' the toilet and therefore prevent dirt and stains from building up in the toilet. 

3. If you have pets, you can use greywater to wash cat litter trays, or to flush away animal waste. Use clean water from the tap only for rinsing after soaping and scrubbing the litter trays. 

4. Use greywater to flush or wash the driveway or other outdoor areas. Use clean water from a tap or hose only for the final rinse to ensure that the floor does not end up slippery, stained or dirty when dry. 

Do you have any ideas to share or feedback to provide on greywater collection and reuse? If so, please email us at!