Dishwasher v hand washing, which uses less water? Which option is more eco-friendly?
While you and I were getting on with our everyday work of cooking and cleaning, the University of Bonn in Germany conducted a study to answer this question conclusively and for good.
The study found, on average, washing a load of dishes by hand (12 place settings), used about 103 litres of water (and an average of 2.5Wh of energy for hot water heating).
How each participant hand washed made all the difference. Some washers used as little as 30 litres of water, others used as much as 450 litres!
Water consumption, technique, competency and cleanliness varied widely between the participants.
However, in comparison, a dishwasher (of the mechanical variety) uses between 15 and 30 litres of water per load (and 1 – 2kWh of energy), depending on it’s efficiency [source].
Even the most efficient hand washer in the study isn’t as efficient as a good dishwasher.
So is hand washing dishes a thing of the past?
For us, it doesn’t make sense to buy a dishwasher. Apart from the upfront costs, we have solar hot water, so hot water heating is practically free. On the other hand, if we used a dishwasher, we would have to pay extra for it’s running costs.
[2015 update: after hand washing dishes for the best part of 35 years (at home and at work), we bit the bullet and bought a dishwasher. We DO pay extra in running costs. But I also love the time saved.]
But there’s still the water issue.
And water security is an important issue, one I think we’ll here more about again as this new drought spreads.
Despite what the study says, you don’t need a lot of water to hand wash the dishes.
In fact, I think hand washers can do just as well or better than 15 litres a load.
Your average sink holds around 20 litres of water. Wash up in a half full sink, and you’re only using around 10 litres of water. Add a little extra water for rinsing, and you can do the dishes in 12 litres of water or less.
If you wash up twice a day, that’s still only 22 litres of water, comparable to a standard dishwasher.
Here are the details.
how to wash dishes using just a few litres of water
1. Scrape plates with a spatula before food has a chance to dry
A spatula is one of your best frugal friends in the kitchen. Scrape out the last of the jam from the jar, the last of the mashed potato from the pot, the last little bit of pancake batter (mmm, crispy dribbly bits) and use it to scrape the plates clean after meals.
To be honest, I’ve always been one to finish every last morsel of food on the plate (and there may be a genetic trait of secret plate-licking, passed down from mother to daughter).
But the kids don’t always finish everything they are given. And hubby has the habit of always leaving something on his plate. One pea. One little bit of chicken. A wodge of mash left on the fork…
I understand in some cultures leaving a little on the plate is meant to be good manners. It says: Yes, thankyou, I’ve had my fill, and no, I’m not a glutton who needs to lick pattern off the plate.
But it still drives me spare nevertheless.
If the food on your plates goes crusty dry before you get a chance to tend to them, soak them for a minute or two in the pre-rinse water…
2. Pre-rinse dishes in a couple of centimetres of water
Dishes need clean water to get cleaned properly, so it’s a good idea to pre-rinse dishes first.
Save water by putting some hot water in the sink, just a few centimetres, and give the dishes a rinse in the sink of water, no running tap, maybe with a quick swirl of a dish brush, to scrub off any remaining food.
This water may get mucky by the end of the rinse, but as this in only the pre-rinse stage, that’s ok.
As with the washing up, rinse the cleanest stuff first.
3. Pre-soak cookware for stubborn stains
While this isn’t strictly about saving water, it does save labour: cooked on food is a pain to wash off.
Make it easy by sprinkling the bottom of your baking pan or fry pan with a little washing soda (same as is in the homemade laundry soap) and pour a little hot water over – just enough to cover the bottom. Leave to soak overnight.
The next morning, give the pan a quick once over with a dish brush, pour the dirty water out and you’re ready to wash the pan, without all the scrubbing, with your next load of dishes.
4. Don’t fill the sink to wash the dishes
All you need to start washing the dishes is a couple of centimetres of hot water in the bottom of the sink and a few suds. The hotter the water the better.
Wash the clean and small stuff first and then…
4. Rinse with hot water into the same sink
Rinse the soap suds off with hot water, directly into the sink.
That way, by the time you get to the pots and larger items, you will have half a sink of water instead of a few centimetres, plenty of water for the larger items.
Alternatively, if you have a double bowl sink, you can put a little water in the second bowl, and use that to dip the dishes in to rinse.
Or, and this is the way my mum does it, pour a jug full of water over the dish drainer to rinse the suds off all the dishes at once, after you have finished.
5. Drip dry
Ok, drip drying dishes has nothing to do with saving water, but has everything to do with saving time!
While it’s possible to use as little or less water than a dishwasher when hand washing dishes, there’s no getting round the fact that it does take more time.
At least by drip drying dishes on a dish rack, you’re not doing any more work than you have to.
Better yet, of course, is to delegate the job of washing the dishes entirely.
I’m still not comfortable with the claim that dishwashers are more eco-friendly than hand washing. They may be more water efficient, and in some cases, more energy efficient than hand washing if you don’t take steps to minimise water use (and sure, they save time and labour, which is nothing to scoff at).
But what about when we consider the environmental impact of their manufacture, the lifespan of a dishwasher (a whole lot less than a kitchen sink) and their subsequent after-life in landfill?
Overall, despite popular consensus, my gut feeling is hand washing is better for the environment that using the dishwasher. Especially if you take steps to minimise water usage (and doubly so, if you have an efficient hot water system).
What are your tips and tricks for washing the dishes? Share them in the comments below.