This is part two of a look at what causes smells from a washing machine and how to get rid of them. The first part looks at problems inside the washing machine (what causes washing machine smells?) but this one looks at smells coming from the plumbing that may be blamed on the washing machine. There’s a link to the first article at the bottom of this one.
Is there a u-bend fitted?If the smell tends to be worse first thing in a morning, and smells a bit like an outside drain, one cause could be that your waste water pipe (on the plumbing) doesn't have a proper U bend fitted. A u-bend always holds some water which acts as a barrier to stop smells getting from the drains back into the house. This water is constantly replaced each time the washer is used. Make sure your washing machine doesn’t pump into a drain system that has a direct run to a drain without some sort of u-bend.
Without it, if the plastic waste water piping hangs over an outside drain, then you have, in effect, an open tube leading from over the outside drain into your house. If the drain hose pushes into a stand pipe at the back, make sure there is a u-bend at the bottom of it.
If yours pumps out under the sink
Most washing machines are plumbed directly into a fitting on the u-bend under the sink these days instead of being pushed into a standpipe (as above). Unless fitted properly though, some of the dirty smelly water poured down the sink can run down the drain hose into the washing machine.
A drain hose connected to a sink u-bend should first go up 3 or 4 inches high (it may need tying up) before running down to the washing machine as shown in the photo. More information – Make sure that the drain hose is connected correctly
More on washer smells
To read more about causes of smells see part 1: washing machine smells
To get rid of stubborn washing machine smells
Try the advice here – getting rid of Washing machine smells