Where a washer waste hose goes into a standing pipe - can it be connected like this? So that it is screwed into some kind of fitting and it's closed. Or would that create any potential issues?
http://jpsplumbing-winchester.co.uk/wp-content/uploads/2016/10/DIY0058.png
I know this is probably not a standing pipe where the drain hose connects, but this is what I basically mean. The way it is sealed or closed to the outside air by screwing into some type of fitting at the top of the standing pipe.
Or in this picture it kind of looks like it is closed off to the outside.
http://i.stack.imgur.com/cyn1J.png
Or could that cause mold or any other issues? What I usually see is the hose hanging over an open pipe. But I can't find anything saying that the open pipe is necessary for a special reason.
If there is a standing pipe behind the washer - I just wondered if it could be attached and a kind of closed system. Thanks

I'm not a plumber but have done plumbing. All I will say is that washers produce lint and the drains often clog, and it's far more convenient to have a removable hose and a removable trap nearby. The trap full of water is what prevents sewer gas from coming out. I'd rather have a clog going back up the stand pipe where I can see it start to overflow, than backed up into the washer.

The reason you don't directly connect to the waste water system is because you can back siphon the waste water into your washer. The way it is normally done is to provide an air gap that breaks the water flow and prevents back flow. Let's say you have some clothing with fecal material in it. Doing it the way you consider could back flow E. Coli into the washer AND possibly into your house water supply.!

Um, okay. You've both completely convinced me! Cheers.

Hello Kelpi, plumbing Code says you have to have P-trap and 30" of stand pipe. You insert end of the hose into the stand pipe - as shown in visual #2

As already described in two previous answers, the first visual #1 is wrong way of draining washing machine. Instead, in this situation you would hang washer hose over the sink edge and had water from washing machine pumped into the sink

Hope that helps

Milo

I'm fairly certain a washing machine drain connection only requires an air break. A bathtub filler / spout, and most sink / basin faucet spouts use an air gap.....