Why do washing machines fill up drum with water right before draining?

[andyr12345]

On certain washing machine cycles (I notice it does this on 60c and more cotton washes , but not on 40c cotton wash) after its done its wash just before it drains (to go to intermittent drain spin) before rinse cycle the drum will fill up with cold water and just revolve the drum a couple of times and then empty . Just curious as i dont see it doing that on every wash cycle programme and wonder what the problem would be with just emptying the water out of the drum at a lovely hot temperature out of the drum?

If it is to cool down 60c (or more temp) before it empties into drain, would it not be better to have some nice hot soapy water go down the drains to keep them clean and sparkly and fresh smelling , rather that cool down the water to lukewarm or nearly cold before draining it?

 

[Whitegoodshelp]

Sorry I missed this, Andy. I think it's a throwback to when it was quite common for washing machines to not be plumbed in.

You used to be able to buy accessories in the 70s (and possibly later), which allowed you to attach the fill hoses to the kitchen taps (very awkward), and attach the drain hose to the side of the sink to pump away the water. The latter was a plastic device, with rubber suction part and a lever, and a spout to push the end of the drain hose on to.

Using the lever, you attached the device to the side of the sink.  In fact, I used this very system in one of my early flats in the early 80s. You had to connect up and disconnect your automatic washing machine each time you used it. If a dishcloth or a washing up bowl were in the sink at the time, water would flood over the sides of the sink.

They topped up with cold water on the hot wash cycles to literally cool down the water to a less dangerous temperature. I can't think why they need it now though.