I was looking for a hose fitting closer to the front of my house when I noticed this valve with what appears to be threaded for a hose fitting right off my water main next to the water meter (Blue circled in the picture below).
Can I just screw my garden hose into it like normal and use it without blowing something up because of pressure or something?
I am not sure if attaching a garden hose so close to the water main will mean it's over-pressurized or something. I don't know about plumbing at all.
As a side note; why are there three water main valves (yellow valves) all so close together (2 right away at the wall and one more after the water meter)?
If I ever need to turn off my water main does it matter which of the 3 valves I use?
The water main comes into the house from the street in the wall in the upper right.
Best Answer
TL;DR: For temporary uses, hooking a hose up to this one should be fine.
There is typically a drop in pressure and volume from the water main to the hose sillcock because of the distance, 90-degree elbows, and smaller diameter pipe in between. Sillcocks close to the water main with full-diameter pipe have better flow so they're more useful for irrigation and such - sprinkler systems are installed as close to the main as possible and with pipes as large as possible for this reason.
This valve probably exists there for drainage purposes, so a short hose can be connected and run to a floor drain/sump pit/toilet. This relates to all the yellow-handled quarter-turn valves that cut off the flow, then the hose can drain water away from that section.
If you're using this for non-drain purposes you'll want to make sure your hose has decent strength, a good rubber gasket, and is screwed in tightly to make sure it doesn't leak. A slow drip on a hose connection outside is fine. A slow drip on a hose in this location would be much more problematic.
Ideally, install a regular (weatherproof/vacuum breaking) sillcock in a convenient location outside as soon as possible and use that instead.