Help I dentifying the purpose of these pipes?

[Fusion916]

Hi all,

In my basement, I have water supply for a sink (which I don't have and wasn't present when I bought the house), and a water supply for a washing machine.

Both of these taps have long caped off pipes in parallel to the water output valve. As I don't anything about plumbing (trying to learn) I have no idea what purpose these parallel pipes serve. Can anybody shed some light?

My second question is about the sewer drain near the floor of my basement. Can someone identify what the thing is I have circled and what its purpose is? Also, does everything in this piping connecting to the sewer need to be rigid? I want to run some ABS pipes to the drain for my washer machine (no drain line to the washer exist).

 

[phishfood]

Those are meant to be shock arrestors to cushion the shock that the piping experiences when the water flow is suddenly stopped. They work fine for a short time, but then the air trapped inside of them is absorbed into the water, and they do not serve their purpose anymore.

I believe that the part circled in your second picture is a backwater valve, intended to prevent sewage backups from the floors above from getting into the washing machine.

 

[camaroderrick73]

Phish is on the money. Definitely a backwater valve.