Need to know
- Dishwashers are more water-efficient than washing up in the sink
- Washing by hand still has its place for many everyday items
- If you don’t have a dishwasher, read our tips for using less water when washing up
These days most of us are pretty conscious of reducing our water consumption – taking shorter showers, letting what’s left of the lawn go brown and switching to a water-efficient front loader in the laundry are all no-brainers.
But what about in the kitchen? If you think giving up the dishwasher to wash by hand in the sink is going to cut down on water use, you might need to think again.
Dishwashers use less water than washing by hand
A full dishwasher uses about 13 litres of water to clean 144 items.
Washing the same load by hand uses about 100 litres of water on average, according to a study by the University of Bonn in Germany.
It's important to note this is average water consumption – actual usage ranged from 33 to a staggering 440 litres in the study!
We'd also hope that Aussies would be more water-conscious than our European counterparts, but there's no equivalent local study.
How much water you use washing by hand
Still don't believe using a dishwasher is more water-efficient?
Let's look at how much water it takes to wash by hand, starting with your sink. A typical sink on the Aussie market ranges from 15 to 45 litres. For argument's sake let's take the median of 30 litres.
Now think about how much you fill your sink when you wash up. If you're settling in for an epic 144-item saga (which makes up a full load in the dishwasher) you're typically going to fill your sink to half to two-thirds full – that's roughly 15 litres – already more than your dishwasher will use, but not too bad, right? Especially compared with the 100 litres from the German study.
The water capacity of a typical sink ranges from 15 to 45 litres.
But think about the last time you had a dinner party's worth of heavily soiled plates, pots and pans to wash by hand. How often did you change the water? Twice? Now we're at 45 litres.
You can minimise water changes by pre-rinsing – but rinsing under a running tap sends your water consumption through the roof. If you have a second sink you can fill it and dunk the plates instead, but you're now filling two sinks, not one.
How long are you running cold water down the drain while you're waiting for it to get hot?
There are water wasters at either end of the job, too.
How long are you running cold water down the drain while you're waiting for it to get hot? You can (and should) save this water in a bucket to use for other purposes, but do you?
And do you rinse the soap off your plates after you've washed them? While it's true you can let your plates dry without rinsing the soap off – it's non-toxic after all – again, do you?
And how much water do you use rinsing kitchen sponges when you're done?
Is it ever better to wash by hand?
A dishwasher is more water-efficient than washing by hand when you have a full load. If you've only got a few dirty things, or you're in a small household where it's not practical to wait until the dishwasher's full, you're probably better off washing in the sink.
And factoring in wooden chopping boards, chef's knives, non-stick pans and other things that you should never put in a dishwasher, hand washing dishes will always have its place.
How to use less water when you don't have a dishwasher
If you have to wash up in a sink, there are some things you can do to minimise water waste.
Let the dishes pile up
Unless you're a degenerate teenager, the sight of a stack of soiled dishes sitting by the sink will likely send you into an immediate cleaning frenzy.
It's better to let those plates pile up and wash them all at once
But in the interests of our war on water waste, it's better to let those plates pile up and wash them all at once – doing the dishes several times a day will naturally use more water. You'll save time too, as you only need to grab the gloves, fill, empty and wipe out the sink once.
Use a bucket
If you've got a large sink, filling it with enough water to wash up may be excessive. Instead, you can effectively reduce the volume of your sink by putting a bucket or tub inside to wash up in.
Even better, use the saucepan you just boiled pasta in. You've got to wash it anyway – and you can count the time you spend washing up in it as soaking time.
And speaking of buckets, use one in the sink to capture the cold water while you wait for the hot to come through – it's good, clean drinking water, and shouldn't be wasted.
Forget the final rinse
Is your final dishwashing step to rinse the suds off your plates? You don't actually have to. It might seem unpalatable, but the surfactants in washing-up liquids are non-toxic, so it's fine to put your clean but soapy plates straight in the drying rack.
But if you're not keen on that, use the cool water that you saved while your wash water was heating up, so not a drop is wasted.
Tip the washing-up and rinse water on your garden when you're done.
Re-use the water on your garden
Ongoing water restrictions mean there's a lot of interest in using grey water from your laundry on the garden, but you can do this with your washing-up water too.
If you're doing the bucket trick then just tip washing-up and rinse water out on the garden when you're done – your plants will thank you for it.
Not using a bucket or tub? Then it's harder but not impossible – scoop your sink contents into a bucket and carry it out that way.
Do an 'office wash'
The 'office kitchen wash' is a good option if you have to clean one or two things – don't fill the sink, just stick your plate under the tap long enough to wet it, squirt some detergent directly on your sponge and start scrubbing. Now give it a quick rinse under the tap again and you're done. As a bonus, your soapy sponge is now wet enough to clean your cutlery or coffee cup without pre-rinsing.
Grab a great detergent
A dud detergent might get your dishes clean, but it'll take more scrubbing, and therefore time. Time's not on your side when you're dealing with a sink full of hot foamy wash water, and you may have to replace the water once it becomes tepid lest it lose its capacity to remove grease.
Choosing a good detergent in the first place can therefore save you time, money and water in the long run.