To save water we need to think not just about the water we use directly, for drinking and cleaning in our home, but also to become more aware of how water is used to make the food we eat, the products we use and to generate the power for our lights and stoves.

One of the top ways to prevent your household from using extra water, is to re-use grey water.

WHAT IS GREYWATER?

Greywater is defined as untreated household wastewater that has not come into contact with toilet waste. 

Greywater comes from baths, showers and bathroom hand basins.  Laundry water from washing machines can also be re-used if environmentally friendly detergents have been used. 

Greywater from the kitchen and dishwasher must not be re-used, because this water may be damaging to plant life because of the heavy loads of organic material, fats, oils and caustic additives.

Greywater can contain the following, depending on the source: bacteria, pathogens, organic material, oil, grease, soap, detergents, pesticides, dirt, lint, sodium, nitrates, phosphates, bleach, hair, skin particles and high salt/pH levels. 

Water from toilets is considered black water, and must not be re-used.

WHY RE-USE GREY WATER?

Greywater can be successfully used for garden irrigation and toilet flushing.  Our gardens consume between 30% and 50% of all domestic water used in summer.

Greywater re-use provides a number of benefits:

•    Reduce potable water consumption.  
•    Reduce the amount of sewerage discharged into the municipal sewer system.        
•    Less strain on septic tank and conservancy tank systems.
•    Saves you money by reducing your municipal water and sewerage bills.
•    Enables irrigation of gardens during drought periods.

WHY GREY WATER STARTS TO SMELL?

Greywater must never be stored longer than 24 hours.  This is the most important rule of grey water re-use.  The problem is that grey water has a temperature and food value for anaerobic bacteria to breed and produce methane and hydrogen sulphide, the stuff that smells so badly.

CAN GREYWATER BE USED FOR ALL TYPES OF PLANTS?

Greywater can be used for almost all types of plants.  Everything from the lawn to the vegetables will benefit from grey water, as it contains plant nutrients.  Vegetables should be washed before using them.  Grey water with a high phosphate level should be avoided in a fynbos garden.

WON’T SOAP IN GREYWATER BE HARMFUL TO PLANTS?

Not all soaps are harmful, good quality soaps are actually good for the garden.  Only soaps and soap powders with a high phosphate level must be avoided.  Plants need phosphate to grow but too much can be harmful over a period of time.

Most new soap powders and biodegradable soaps will not harm your plants, but try to avoid introducing bleach and harmful detergents into your grey water tank.

HOW CAN I REUSE GREYWATER?

Bucketing:

The advantage of bucketing is that it doesn't require modification to the plumbing of your home, or installation of a grey water treatment and irrigation system. The greywater can be collected directly from the bathroom and laundry into a bucket, and applied to garden or lawn areas.

Basic greywater systems:

The most basic greywater system employs a submersible pump to automatically pump out the greywater as soon as it enters the tank.  The pump is connected to a static sprinkler head by a garden hose, which you’ll have to move regularly to ensure even watering.  A float automatically switches the pump off when the tank is empty.  A basic filter can also be installed before the grey water enters the tank.

OPERATION AND MAINTENANCE

Once a greywater system is installed, it becomes the house owner's responsibility to ensure it is operated and maintained according to the manufacturer's instructions.

Some greywater systems may require weekly cleaning or replacement of filters, desludging of tanks, the manual diversion of grey water back to the sewer in winter, flushing of the irrigation lines, and occasional replacement of pumps. 

Greywater systems must never be connected to municipal drinking water systems.

GREYWATER RE-USE SYSTEM

Greywater is different from fresh water and requires different guidelines for it to be re-used.

1. Don’t store greywater longer than 24 hours. If you store grey water, the nutrients in it will start to break down, creating bad odours.

2. Minimize contact with greywater. The grey water system should be designed for the water to soak into the ground and not be available for people/children or animals to come into contact with grey water.

3. Don’t use greywater if a household member is sick.

4. Don’t re-use nappy washing water.

5. Infiltrate greywater into the ground, don’t allow it to pool up or run off. Pooling grey water can provide mosquito breeding grounds, as well as a place for human contact with greywater.

6. Keep your grey water system as simple as possible. Simple systems last longer, require less maintenance, require less energy and cost less money.

7. Install a valve for easy switching between the greywater system and the sewer/septic system.

Greywater use is entirely at the risk of the consumer.  The Overstrand Municipality cannot be held liable for any consequential damage or loss arising directly or indirectly therefrom.