What is this.. growth?

What would cause this formation or growth? Almost looks crystallized? Noticed it about 2 months ago and it was the size of a quarter but now is much larger. Can it be the result the a small leak no (we do have very hard water,but no evidence of water down below)? I am afraid to “break off” or displace whatever is there for fear of an open leak.

Dishwasher Water Hammer Arrestor

I'm replacing my dishwasher supply line and considering adding an arrestor to eliminate some of the water hammer that occurs when I run the dishwasher. Do these devices actually help, or create more problems than they solve?

What is this at the end of my pipe?

This is buried up in my basement wall near the exterior of the home. The opposite side of the T is my sprinkler shut off valve that I need to move. Plumber is coming in a few days, but I'd like to know what this is before he shows in case I have to remove more drywall for him to work. Thanks in advance.

What is this?

This is in I’m back yard in a round valve box in the ground in my back yard. Looks like some sort of valve. What are these typically used for?

Radiator pipe sticking out into bedroom, is this normal/safe?

Hi all, I just moved into a rental apartment in an old building (late 1800’s) and this pipe is sticking out into the corner of my bedroom. From the placement it seems to be coming from the radiator in my bathroom. I’ve never had steam heating before, is this normal? Also, Is it safe to put furniture next to it? There’s no other place for my desk I can think of. I would be running wires along my desk, but not touching it. Thanks for your help!

Can I replace the valve on this water hammer arrestor?

Transfer Valve plumbing first thoughts

All the connections bothers me. Should it?

What would cause this?

I turned the kitchen faucet on and the water came out like this. I tried the bathroom and it was clear. Then, I ran the kitchen faucet a bit longer and it eventually came out clear. So what is up plumbing?

How can I stop loud banging of waste water pipe?

In my bedroom I have this large waste water pipe that spans the length of the wall. Whenever folk in the flat or below us use water it causes the pipe to give this loud continuous banging. V annoying and hard to sleep through. Landlord sent contractors who cut this hole in the dry wall (level to head) and attached the pipe. This helped for the first week no noise but it quickly came much further up the wall above the hole where I can’t reach. Is there anything I can do to prevent this happening?

Has anybody used these or even heard of these before?

Straub coupling, apparently it's good for 26 bar, which equals 377 psi!? I use them on blown out pvc water mains when we can't wait for glue to cure. Lots of pvc mains here in SoCal

What needs to be done

Need help from someone that is in a little more in the know than I am with this. What am I looking at here and how urgent of a fix. This is a pipe above my water heater from the house we just bought. Thanks!