How to Reuse Waste Water

The widespread availability of clean water to drink and wash with is one of the wonders of the modern age (and something many of us take for granted). It’s also a huge source of waste. Every time we leave the tap on while brushing our teeth, flush a toilet or overfill a sink, we’re drawing more water than we actually need through the system. Fortunately, we can limit this waste through careful re-use of the water in our homes.

What types of waste water are there?

While we might imagine that everything that goes down the plughole ends up in the same place, there are actually two different sorts of waste water:


This is the water you get from your showers, basins and taps. The water that drains here might be dirty – but it’s not nearly as dirty as…


This is water that comes from your toilet. As such it contains human waste and other contaminants which make it unsafe. The waste water from kitchen sinks and dishwashers should be considered blackwater, as when it drains it’ll contain a high concentration of chemical detergents – as well as the grease and food waste that might have been lingering on your crockery.

How might we use waste water?

Clearly, it’s not safe to drink the water you’re just showered with. It is however, safe to use it elsewhere in the home and garden. You’ll likely need to do some investigation to determine where your greywater and blackwater supplies are being sent. In urban areas, you might find that you have a direct pipeline running from your house to the local sewage system. Fortunately, it’s possible to re-use greywater without getting into the pipes at all – you need only place a bucket in your shower the next time you use it.

More problematic is storing greywater. This is because if it’s left standing for longer than 24 hours, harmful bacteria can multiply to dangerous levels. If you want to avoid water-treatment, use your waste water as quickly as possible.


A washing machine represents the most convenient source of greywater in most households. It allows you to divert the waste water to a new destination without the necessity of interfering with the existing plumbing. A machine will come with a pump which you can pipe directly outdoors to your plants – or you can simply fill up a bucket or watering can.

If you’re looking for a point of entry to the world of water recycling, then this might prove attractive – it’s easy, and it’ll allow you to reap the benefits of water recycling without having to worry about the problems of filtering and treating water during storage. Be sure to use a detergent that’s low in phosphorous and salt for the best possible results in your garden.


If you’d like a more automated greywater system, then you might pipe it directly from your home into your garden. A slotted pipe or a specially-built dripline will be able to slowly water your plants every time you wash your hands.

garden sprinkler

You’ll need to ensure that the pipe extends away from the foundations of the house before the slotted section begins, in order to prevent leaking water from damaging your foundations. You’ll also want to cover the pipe with rocks so it doesn’t get damaged the next time you dig up your flowerbed.

It’s worth considering that the greywater supply will be sporadic. Larger plants and trees will be better equipped to deal with this, as they’ll be able to store more moisture for later use – smaller plants, on the other hand, might be overwhelmed if the soil is oversaturated.

What about my vegetable patch?

Bear in mind, if you intend to water vegetables using untreated greywater, that you won’t be able to eat them raw – since the water might not be safe to drink. To be extra-safe, it’s best to avoid watering edible crops with greywater entirely; collected rainwater will do the same job more safely.

What about inside the home?

Greywater is clean enough to be re-used to flush your toilet – and indeed, it’s hugely wasteful to literally flush clean, drinkable water down the pan. In order to store it, however, you’ll need to invest in, or construct, a storage tank with a built-in filtration and treatment system that’ll prevent harmful microbes from growing inside. When you consider that toilet flushing is one of the major uses of water in the home, this becomes even more sensible.

Blackwater is a great deal more limited in terms of re-use potential. It can only be used outdoors, and only after it’s been thoroughly treated and disinfected. Barring exceptional circumstances, it’s best to avoid trying to re-use blackwater entirely – as the cost of doing so, and the risk of doing it improperly, will almost always outweigh the benefits.

In conclusion

Recirculating waste water will help to slash the amount of money you spend on water, and reduce your ecological footprint. That’s because it’ll reduce the strain on the sewage treatment infrastructure, and the energy required to get water back into your home. It’ll also allow you keep your garden properly watered during especially hot spells where the water supply might be restricted.

But there are downsides, especially if you’re going to install an automated waste-water recycling system that’s linked in to your plumbing. This will require an investment of time, effort and cash – and you’ll need to decide whether it’s worth it. This will mostly depend on the availability and price of water in your area. If you’re able to obtain water cheaply and the supply is uninterrupted, then a reuse system will be less attractive than if water is expensive and inconsistently available.

You should also consider the amount of time you’re looking to stay in your property – as, clearly, if you’re going to be moving out in the near future, you’ll get less use from your system. While a competently-installed water-reuse system will inflate the value of your property, it’s not a particularly easy means of doing so.

With all that said, it’s worth considering that you don’t need to be very elaborate right from the start – even a system as rudimentary as a bucket in your shower can afford you a supply of effectively free water to use in your garden. How much further you go from there will be up to you!

13th Feb 2017 Ship It Appliances Ltd

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