Which is better for the environment – using a dishwasher or washing dishes by hand?
Last week for our Change the World Wednesday challenge we looked at water conservation and it got me thinking about the whole wash-by-hand vs dishwashers argument again.
Participants of last week’s challenge shared some top tips for reducing water usage when clearing up after a meal.
One of them shared that when washing the dishes by hand they filled up the sink with water instead of using a running tap. Another said that she turned the water off while washing up and put it on again to rinse.
One of the best ideas was to reuse dishes and cups throughout the day. This is something we do at home; we each have our favourite cup, and as we mainly drink water they really don’t need washing any more than once a day. Plates that have only crumbs on them are scattered outside for the birds and the plates are wiped clean before reuse.
For people with dishwashers, it’s best to only run the machine when completely full in order to save both electricity and water. And if you check some dishwasher reviews, you’ll find some models that have eco friendly settings for even more savings.
But it is better to use a dishwasher or wash by hand? This is something that’s been on my mind for many years since reading that the impact of using a dishwasher was less than washing by hand.
I don’t actually have the answer, but here are some of the things I’ve been thinking of:
PRO WASHING BY HAND
- If you heat water to wash by hand using say, a gas combi boiler or tankless water heater, or in our case, wood, is this better than a dishwasher which heats water from cold using electricity? (Assuming the electricity is not sourced from solar or other renewable energy).
- I’ve not yet found anyone who claims to have found an effective eco friendly dishwashing detergent; whereas when I wash up by hand I don’t use any detergent apart from cleaning greasy items. Friends have had to replace their glassware too due to etching.
- How much energy is contained in the manufacture and running of a dishwasher and its final disposal, compared to say a washing up bowl and some cloths?
PRO DISHWASHER
- I can wash up an entire meals’ worth of crockery and cutlery in a bowl of water unless it’s greasy. A dishwasher only uses around 16 litres of water for a full load (6-8 place settings) which seems incredibly low. But in all honesty, I sometimes run the hot tap and I think many people do this too.
- If you’re using an immersion heater to heat water for washing dishes, it’s less economical than using a dishwasher. To heat an immersion tank uses around 2.5kWh of energy. To run a dishwasher uses, on average 1.4kWh
- If you have a dishwasher with an ECO mode you’ll be pushed to be able to wash up by hand as well by using the same resources! You’d need to be using about a cup of water to wash a plate; and that’s pretty impossible.
It seems that taking modern technology into account, the cost of managing a dishwasher is less than washing by hand. But I’m still not convinced about the overall impact when you take into account the manufacturing and end disposal.
What do you think? Which is better for the environment – washing by hand or using a dishwasher?
Thanks for this discussion – it’s something I’ve thought about a lot too. I don’t have the answer, but I can add a couple of points on energy use.
In general, using electricity to heat anything is less efficient in terms of fuel usage than using gas or wood. This is because every time energy changes from one form to another, some gets lost (to us – we don’t have 100% efficient processes). A power station burns fuel which creates heat. This then drives a turbine – change no. 1 – turning the heat into kinetic energy. The turbine is connected to a generator – change no. 2 – converting kinetic energy into electricity. The electricity then comes down wires to your house, where – change no. 3 – you turn it back into heat in your immersion heater, dishwater, or tankless water heater (I’m assuming that’s electric-powered). On the other hand, a gas boiler in your house burns fuel which creates heat. You then use the heat.
As for comparing different types of electrically-heated water, e.g. immersion heater vs. dishwater, I think that’s a little more complicated than you suggest because having heated your immersion tank, you wouldn’t use all of it for the washing up. If you can use the rest while it’s still hot then it doesn’t look so inefficient.
My gut feeling is that a bowl of hot soapy water must be more efficient than a machine, and that manufacturers focus on water used to distract us from the electricity used. And as you rightly point out, the manufacture and disposal costs are ignored altogether. On the other hand, gut feelings are pretty unreliable, so I shouldn’t trust that too much.
At the moment, my washing up water is heated in the kettle (I will get those solar panels one day!) which takes about 0.2kWh for a day’s worth of washing up, maybe twice that if I have greasy pans. I just had to time my kettle boiling to check that, so now I have to go and wash up!
I don’t know the answer either but, like Rachel, my feeling is that a bowl of water should be better. Manufacturing and transporting a bowl uses far fewer resources than a big dishwasher. Also, although a dishwasher uses less hot water than washing by hand, it appears to use a lot of electricity, and hotter water than I would want to use to wash dishes by hand. There is also the problem of glasses, and no doubt other items too in time, becoming etched and having to be replaced. The figures on the dishwasher website reached from the link above indicated that a most enormous quantity of hot water would be needed to wash dishes by hand. I could not imagine needing that amount of water however dirty the dishes were! I have never had a dishwasher but, when I have been to places where dishes are washed in a dishwasher, I have noticed that the dishes tend to smell quite unpleasant, which I have always assumed indicates a film of detergent full of chemicals.
I agree it is a close one to call. We are a family of 5 and do have a dishwasher. It goes on once a day on Eco mode packed full with the dishes from the day’s 3 meals. We didn’t have one until the third child started eating proper meals and we needed to fill the sink twice to get through all the evening washing up.
We use dishwasher tabs which are excellent by Ecozone. They are Phosphate free and safe for septic tanks. They even have a soluble wrapper so the only packaging waste is the recyclable cardboard box that they come in. They also contain a rinse aid but we also use white vinegar as an extra which works well and super cost effective.
Lucy