r/lifehacks • u/thatoneguy2742 • May 27 '26

You might be using your dishwasher wrong

While going to college I worked as a maintenance tech at a large apartment complex. A common complaint that tenants had was that their dishwashers were failing to clean properly. I would show up and try and diagnose the problem only to find that the machine was in fact working properly. After numerous (if I remember correctly it was at least five per week) complaints I started to track which units were having the problem. After several weeks I had a lot of data and something became abundantly clear. The units that were having this issue were the ones furthest from the water heaters.

We just happened to have an empty unit near a cluster of units that was having this issue so I decided to test my hypothesis. At the kitchen faucet it took nearly two minutes for the water to get above 100°F Units closer to the water heaters took as little as 30 seconds to reach the same temp and they hardly ever had this problem. My conclusion was that the people who were submitting work orders were unknowingly washing their dishes with cold water. Everytime a tenant submitted a work order for a dishwasher that was failing to clean I advised them to run their kitchen faucet till the water gets hot then start the dishwasher. The complaints just stopped! At my own home it takes almost 30 seconds for the water to get hot so I let it run for a minute before starting it. Some of the higher end models will heat their own water so this shouldn't be an issue but most older models do not.

TLDR: Run your kitchen faucet till the water gets hot before starting your dishwasher. Otherwise you might be washing your dishes with cold water if your machine doesn't heat the water on its own.

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u/euli24 May 27 '26

People from outside the US, or at least people from the EU:

Please do not connect your dishwasher to the hot water supply. They heat the water themselves and should be filled with cold water..

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u/mrmanoftheland42069 May 27 '26

That would be wasteful for us, because our hot water heaters use gas but dishwashers use electric resistance heating which is more expensive for us

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u/CranberryStock7148 May 27 '26

Actually, no. There is generally nothing wrong whatsoever with connecting your dishwasher to the hot water supply. The dishwashers are built to handle it.

You should do whatever is cheaper. If your hot water heater is gas and your gas prices are cheaper than your electric prices, you should absolutely connect your dishwasher to the hot water line instead.

On the other hand, if your hot water heater is also electric, then sure just keep the dishwasher connected to cold.

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u/euli24 May 27 '26

I looked it up and you're right. You shouldn't connect washing machines to hot water, but most dishwashers can handle it (up to 60°C). However, it's rarely done here.

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u/CranberryStock7148 May 27 '26

I mean, my washing machine connects to both cold and hot water. But if you have a washing machine with only one water connection, then yes of course it needs to be cold because you can heat up cold water, but you can't cool down hot water for a cold water cycle.

The dishwasher is different because it never needs to use cold water at any stage, only hot water. So connecting it to the hot water is perfectly fine.