Pros & Cons of Recycling Greywater at Home

This article is written from an Australian perspective but the grey water facts are relevant to many countries. Remember never to store grey water in tanks for longer than 24 hours as potentially harmful bacteria and other microorganisms could begin to multiply in the water tanks. Greywater should preferably be used instantaneously if you want to use it as untreated garden irrigation water.

What is grey water?

‘Grey water’ is simply the waste water from your shower, bath, spa, hand basis, laundry or washing machine.

Any water that’s been through your taps, washing machine or bath is ‘grey water’.

Once seen purely as waste, grey water is now being embraced as a source of additional, unrestricted water for the garden, toilet and clothes washing.

The water from your the kitchen sink and toilet is so heavily loaded with organic matter, fats and chemicals that it’s called ‘black water’ – it’s not suitable for re-use around the home or garden.

Putting grey water to good use

Around the home and garden, recycled grey water can be used for many things, such as:

At home

• Flushing the toilet
• Washing clothes

Around the garden

• Irrigating plants
• Irrigating vegetables (treated water only)

Recycled water can’t be distributed directly onto the lawn or garden.

Generally speaking though, it’s not recommended that you pipe grey water directly onto your lawn or garden. In some states, such as NSW, it’s actually illegal.

Benefits to the homeowner and community

Grey water use reduces the household’s need for fresh water.

Because there’s less reliance on fresh water, your water bill will decrease. It’s been estimated that just over half of total household water could be recycled as greywater,  potentially saving hundreds of litres of water per day**.

It also has broader community benefits in that it reduces demand on the public water supply – this can be a real relief during times of water restrictions.

Grey water reduces the amount of waste-water entering sewers or on-site treatment systems.

Domestic water is literally flushed down the drain in most homes.

Obviously there’s still a saving to the homeowner here, but again, society benefits because less resources are wasted having to filter, treat and transfer sewerage, while rivers, creeks and oceans are kept cleaner.

Potential risks

Using untreated or under-treated grey water on the garden may be relatively cheap and easy, but can be risky because it:

• May expose you to disease-causing pathogens;
• Salts and chemicals could damage your plants and soil;
• Excess run-off could escape your boundaries and create problems for the neighbours.

How is grey water recycling regulated?

Regulations on grey water re-use differ in each state, and council to council, so check with your local council or state Environmental Protection Agency before commencing this journey.

You’ll also need council approval to install a grey water treatment system (and the application itself will be an additional cost). Some grey water treatment manufacturers may be able help you through the approval process, as it’s a relatively new phenomenon for many local councils. But in order to obtain council approval, you’ll need to call in a licensed plumber for proper installation.

Recycling water in your home

There are two main options for grey water re-use:

1. Direct diversion, or
2. Installing a domestic grey water treatment system.

Grey water use is not affected by water restrictions; you are free to use as much as you like, whenever you like.

The best option for you will depend on how much grey water you produce, the size of your garden, and your budget.

Direct diversion

This is when grey water is diverted directly to your garden or lawn using a licensed piping system.

You can divert water for underground irrigation.

It’s an affordable option but it has its limitations.

These are some of the restrictions:

• Diverted grey water can only be used for sub-surface irrigation – in other words, you can’t pipe it straight onto your garden or re-use it in the home. You need to divert the water to an irrigation system that sits below the surface of the ground;

• Diverted grey water can’t be stored because bacteria can multiply – so it has to be re-used immediately;

• The piping needs to be installed by a licensed plumber;

• Local water suppliers tend to have different guidelines around the use of grey water;

• During wet weather, grey water needs to be directed to the sewer.

Domestic grey water treatment systems

A domestic grey water system collects, stores and then treats (or even disinfects) grey water.

Grey water recycling systems collect, store and treat water before use.

Different systems treat the water to varying levels of purity and hygiene. For instance, some treatment systems will only allow you to directly water your garden, while some allow you to re-use the water for toilet flushing and in washing machines.

The cost of set up

Setting yourself up for grey water re-use is expensive thanks to the initial set-up costs, and long-term maintenance.

Installing a diversion system is likely to cost you around $1000-$2000, while a grey water treatment system can cost between $10,000 – 15,000. So for many, the upsides to grey water recycling has to be viewed in terms of its long-term cost-benefit.

The value of a grey water treatment system will be balanced out over the long-term due its high cost.

For some, a viable alternative may be a rainwater recycling system. For others, especially those that live drought-affected parts of the country or those that have to rely on rainwater for household water supply, a grey water treatment system could provide a lot of assistance, as well as savings.

The verdict

Installing a grey water treatment system will definitely reduce how much water you use (especially if teamed up with a decent-sized rain water tank) and reduce the amount of water going into the sewerage system.

While it won’t necessarily save you much money due to the high initial outlay compared to what you pay for water generally, for many this will be irrelevant – peace of mind isn’t something you can set a dollar value on.

The information in this article is for general interest and is not intended as advice. Consult an experienced professional and be sure to contact your state Department of Health and Environment for a list of approved grey water treatment systems.

Source: Realestate.com.au (By Caroline Bruckner)

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