Posted on September 5th, 2022.

The water from your washing machine, shower and bathroom sinks, or the lightly used wastewater flowing out of your home can be reused in a multitude of ways.

Unlike the contaminated ‘black water’ from your toilet and kitchen sink, greywater is easier to purify. It is also loaded with nutrients that can feed your plants. It is, in short, liquid gold. In days past, it was common to have a garden patch close to the dishwashing area or bathroom of a house, watered by the run-off from these areas. Here, all manner of food crops: banana, spinach, herbs and vegetables would be grown to meet the needs of the family.

Many modern houses have systems of greywater purification and reuse. The water can be reused for irrigating the garden, flushing toilets, cleaning vehicles and outdoor areas. It reduces our dependence on clean, fresh water and lightens the burden on local water treatment plants. It also saves us a whole lot of energy and money and allows us to stretch our limited water supply for longer.

Washing machines account for about a quarter of domestic wastewater. Depending on your machine, (fully automatic front-loading machines are said to use less water and energy than top-loading ones) you generate between 32 and 199 litres per wash. So, if you wash your laundry 5 days a week and own a particularly water-intensive machine, your house could be producing over 1000 litres of wastewater per cycle. That’s good, clean, freshwater all going down the drain!

Imagine if every household in India diverted this water away from the drain. Our country could be well on its way to water security.

What Does Washing Machine Run-Off Contain?

Most commercial laundry detergents are a cocktail of chemicals. They contain:

Phosphates meant to soften hard water.
Sulphates which soften the fabric.
Chlorine-based bleach and optical brighteners which make clothes appear whiter.
Surfactants and foaming agents which loosen the hold of dirt on the garments.
Fragrances which lend the laundry a pleasant smell.

To add to this, laundry detergents are highly alkaline, with a Ph value greater than 10. This might help rid clothes of dirt, but it is disastrous for biological systems that prefer a Ph between 6 and 9.

All this means that the water coming out of your washing machine is not very eco-friendly. It is high in biological oxygen demand which is the amount of oxygen consumed by bacteria and other microorganisms while they decompose organic matter.

It is also low in dissolved oxygen. Municipal sewage treatment plants, plagued by the high volume and cost of treating this water and faced with inadequate infrastructure, release this water untreated into water bodies such as lakes and rivers. When laundry detergents enter an aquatic ecosystem, they wreak havoc on it. The water is rich in nutrients, which in itself sounds like a good thing but isn’t.

Laundry wastewater contains phosphates — an ingredient that has been banned from detergents by several countries. Phosphates are used in commercial fertilisers because they aid plant growth. But, flowing in large volumes into waterways, they support the growth of algae in lakes and rivers. Algae consume all the dissolved oxygen in the water, leaving nothing for the fish and other marine life, thus killing them.

Further, as evidenced in the case of Bellandur Lake in Bangalore and the River Yamuna in Delhi, they pollute the water, destroy marine life and cause froth formation and foul odour. An alarming truth is that, as much of India receives increasingly hard water, the detergent industry compensates by making turbo-charged products loaded with extra phosphates and surfactants to make cleaning easier.

How to Improve the Quality of Laundry Wastewater?

When you collect greywater, you want it to be as safe as possible to minimise damage to your garden, vehicles and household fittings. It is, thus, best to steer clear of detergents containing the chemicals mentioned above. If you do not find the ingredients mentioned on the label, contact the manufacturer requesting a disclosure. Or better yet, switch to an alternative that is free of these chemicals.

Downsize your wastewater by reducing the frequency of laundry washing. Wait until you have a full load before running your washing machine. You could also try cutting back on the amount of detergent you use per cycle to minimise the number of toxic chemicals you send out into the environment.

Always wash clothes in cold water. This reduces the number of microfibres shed by your clothes, especially synthetic ones. Microfibres are tiny plastic strands contained in nylon and polyester garments. When washed, they are released into the waterways where they cause damage to the marine habitat and the organisms that live there. These fibres are so tiny that they escape the lint filter in most washing machines. Using a liquid detergent, lower washing machine temperatures and using a front-loading washing machine can reduce microfibre shedding.

If it is feasible, set up a greywater treatment plant in your house. Options occupy the spectrum from the simple and cost-effective to the elaborate and expensive. If you live in an apartment, you could instead store the greywater in a bin or bucket and use it within 24 hours.

Alternatively, if you live in an independent house and use an eco-friendly detergent, allow the pipe of your washing machine to directly irrigate your garden.

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