Strange pipe leaks large volume of water to outside

[jamesmorlock]

Hello.

I was hoping the DIY internet community could help me solve a problem I've been having with a strange pipe that constantly leaks a large volume of water to the outside of my house. The small pipe in question diverts from the outside faucet, before the shutoff valve. Therefore, the leak continues even if I close the valve.

A few things I noticed about it:

• 
  It leaks a huge volume of water constantly near the foundation of my house, approximately 8-10 gallons per hour

• 
  The pipe appears to be an afterthought, probably a temporary fix from the previous homeowner, due to the amateur looking welds and scorch marks on the wood.

I don't understand the purpose of this pipe. It was definitely not done by a professional.

http://postimg.org/image/mna15adl1/ : outside 1
http://postimg.org/image/48zi1b1ad/ : outside 2
http://postimg.org/image/lnobnbnt1/ : inside 1
http://postimg.org/image/jkdwfno05/ : inside 2
http://postimg.org/image/bu74ailol/ : inside 3

Any theories on why this pipe is present, how to shut it off, or what I should do to fix the situation at minimal cost is greatly appreciated.

 

[johnjh2o]

It looks like a pressure relief valve. Are you on city water or a pump?

 

[jamesmorlock]

I am on city water, in a small subdivision.

 

[johnjh2o]

You may need a pressure reducing valve or if you have one it may need replacing. Get yourself a pressure gauge that attaches to your hose bib and tell us what it reads.

 

[jamesmorlock]

I tried adjusting the valve, and it seemed to have no effect on the house's water pressure or the leak. Seems logical that it would be broken. I will head to Home Depot in the morning and test it with a gauge before rushing into a repair.

It also seems logical since I have other, seemingly unrelated problems such as random leaky pipes, leaky toilets, etc. Based on my online reading it seems a broken valve could cause all these things.

Thank you for the reply. I will follow up with a reading shortly.