Cold Fill vs Hot Fill Washing Machines (explained)

If you have recently moved into an older property and had to plumb your existing washing machine in, you would probably have noticed there were two taps available to connect your washing machine inlet water hose into. One with a blue tap and one with a red tap, the colours signify the water temperatures, blue for cold and red for hot.

If you own a relatively modern washing machine it’s likely that it only has one inlet hose. That’s because for a number of years now most washing machines only fill with cold water. Which leads to the question, why? Is it because using cold water to fill a washing machine is more energy efficient? What does hot water do to a washing machine? What does cold water do to a washing machine?

So many questions and, as far as we can see, no decisive answers. And that’s the reason for this article, to look into the difference between cold fill and hot fill washing machines, the benefits and drawbacks, and what it means to us, the customer.

Hot Fill Washing Machines

When washing clothes on a hot wash, the machine obviously needs hot water. Hot fill washing machines obtain this hot water from the hot water supply of your home. Usually via the same pipes that provide your taps with hot water. The hot water is pumped into the washing machine’s drum as and when it is needed directly from your home’s hot water supply.

Cold Fill Washing Machines

Cold fill washing machines can still wash clothes on a hot wash, but the cold water drawn directly from your home’s cold water supply is heated within the machine as and when needed. These machines feature a number of cooler wash cycles that are intended to use cooler water. These cycles are supposed to be perfect when used in conjunction with biological detergents because the enzymes in these detergents work best at low temperatures and are killed at higher temperatures.

Why Have Cold Fill Washing Machines Been Introduced?

The argument used by washing machine manufacturers to support their choice to make cold fill washing machines is that the majority of consumers use cooler washes nowadays and so there’s no need for a hot water feed any more. They also claim that it’s far more energy efficient to heat the small amount of water used in a modern washing machine in the machine, than to use the largely inefficient hot water systems found in most homes.

However, many people don’t use biological detergents and therefore don’t need to use cooler wash cycles. Plus many people nowadays have solar powered hot water supplies which cost nothing to heat water and have no impact on the environment either.

Taking a purely cynical viewpoint just for a moment, could the reality not be that it’s less costly for manufacturers. They no longer have to include any of the components that are needed to convey hot water through their machine which in turn reduces manufacturing costs. 

Manufacturers would counter that claim by saying that the small amount of water needed to run modern washing machine programs would probably arrive at the machine colder than needed if taken from the home’s hot water supply due to the length of pipes from the boiler to the machine. Which would mean the machine would still have to heat the water to the desired temperature.

What About Boil Washes?

It is far more efficient to draw water from a hot source for use in a washing machine’s boil wash even if that water has cooled off slightly on its journey to the machine from the boiler. Washing machine manufacturers claim that most consumers hardly (if ever) use the boil wash program. However they recommend using a boil wash once a month to prevent any buildup of bacteria and foul smells in the washing machine.

This means we all should use a boil wash at least once every month which can cost more, take longer and wear out the heating element and other components on the washing machine. Plus with so many people now using alternative types of energy to heat their water, it would be far less expensive to use a hot fill.

If you use a lot of boil washes and need to heat the water from a cold fill, it takes longer for the wash program to run. Which in turn, could add to the wear and tear on your washing machine. However, the longer wash programs are not limited to hot washes.

Modern washing machines using a cold fill only system take longer to run wash programs due to the use of less water in general. Which means longer rinse cycles and so longer wash cycle times are not only due to hot washes.

Washing Machine

Cold Fill Or Hot Fill: Which Is Better?

It would seem to us that it’s all a question of eras. Back in the good old days, washing machines needed both hot and cold fills to be sure of getting the clothes clean. Then came the advent of enzyme rich biological washing detergents which took away the need for hot fill machines.

It was then discovered that without boiling hot washes bacteria and germs could increase to such a level within the washing machine that there would be foul smells every time we opened the washing machine door. Then came the introduction of alternative energy supplies (solar, wind etc…) and many homes have access to free hot water.

So to answer which is better, would depend completely on your situation. Do you:

  • Use a boil wash regularly?
    • If so hot fill would be better for you
  • Only use a cool wash program?
    • If so cold fill would be better for you
  • Use biological detergents?
    • If so cold fill would be better for you
  • Have access to an alternative energy supply?
    • If so hot fill would be better for you

Frequently Asked Questions

Is it better to have a hot or cold fill washing machine?

Whether it is better to have a hot or cold fill washing machine depends on your washing habits. If you prefer to use biological washing detergents then a cold fill washing machine will be best for you. However, if you use a lot of boil washes it would be more beneficial for you to have a hot fill washing machine.

Are new washing machines cold fill only?

The majority of new washing machines are cold fill only but there are some hot fill machines still available. The idea is that cold fill machines are more energy efficient and most people only use cooler wash programs anyway. But this is not always the case even washing machine manufacturers recommend performing a boil wash at least once a month to remove bacteria from the machine that cause foul smells.

Why are all washing machines cold fill?

The majority of modern washing machines are cold fill only because the manufacturers claim that hot water kills off the enzymes in biological washing detergents that are supposed to remove stains and germs.

Is there a downside to washing clothes in cold water?

There is a downside to washing clothes in cold water which is that cold water doesn’t sanitise clothes or remove germs or insects from clothes.

Should you wash towels in hot or cold water?

You should wash towels in hot water to remove germs, stains and bacteria. Washing in cold water is recommended to prolong the life of towels but even using biological detergent, some bacteria can remain.

One comment on “Cold Fill vs Hot Fill Washing Machines (explained)

  1. Another pro for hot fill.
    We have a water softener in the roof space that is connected only to the water storage tank. Therefore, downstairs washing machine is cold fill only from a direct supply. We might go to hot fill, if we can find one, to take benefit from the softened supply.

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