22mm old galvanised pipe, sewage sludge comes

[new2000]

Hi all

I recently bought a property. While cleaning up the garden, I found an old corroded galvanised pipe, ~22mm. Very deep into the ground, one end is connected to a piece of 22mm copper pipe and closed off.

The water to the property is connected by polycorp pipes. I closed off the water at the main meter at road.

Then made a small cut on copper pipe, and sewage sludge comes out at high pressure. I resealed pipe by hammering pipe closed.

Where is this pipe coming from, too deep to easily trace, does not stop even though main water is closed.

and sewage comes out?? I have a normal square hole, brick sewer, that is far away from the pipe.

I am going to get a plumber, however any ideas as to why a 22mm water pipe would be connected to the sewer system.

 

[desiganp]

Just a guess : there could be a septic tank on the property.

 

[airborne]

Could be an old pipe that was in use once, maybe an old outbuilding that was removed and the pipe remains connected to the main plumbing system. At the time instead of digging all the pipes up from the outbuilding to the junction on the main pipe they just plugged the end of the pipe, hence when you cut into the pipe above the end point it started leaking.

That being said 22mm isn't a common sewage line pipe size, a decent sized log will block that in no time so it would be an unusual choice for a sewage pipe.

Another point to note is unless you release all the water pressure by opening taps all around the property after turning the mains off the pipes will still hold significant pressure.

 

[new2000]

Thanks, I will check if there is a septic tank.

I let the taps run a while after closing the main, there was still full pressure from the pipe.

 

[airborne]

Thanks, I will check if there is a septic tank.

I let the taps run a while after closing the main, there was still full pressure from the pipe.

You have to let all taps run dry, even then there can be residual amounts of water and pressure in some parts of the system.