help finding the water supply blue pipe

[Zehroni]

before I started my extension 2 years ago, Thames water redirected the main water supply and run it along side the house. however, they fitted a lot of reduction adaptors to connected it to the 15mm pipe inside the house. I am in a process of upgrading the heating system by installing an unvented cylinder and was advised that it would be better to replaced the water mains inside the house to 22mm instead of 15mm. running 22mm from the point of entry to the house to where it needs to be internally is not an option as I have have just completed tiling the floor. the best option is to intercept the water main pipe in the pathway alongside the house and put a T to branch it to where the cylinder will be located. in another word I will have 2 entry points of water to my house. I dug across the pathway at a depth of 700mm but but can not find the pipe. how deep I need to dig? is there any device I an use to tell where the pipe is and how deep down?

 

[muggles]

Regulations say the pipe should be 750-1350mm below the surface. Thames Water may have a record of where they put it

 

[tell80]

First you have to find the blue mdpe, start from the external shut-off. How far is it from the extension?Where was the internal shut-off before the extension?

The utilities i'm aware of dont work on internal installations they
would only connect a new supply, your blue plastic, from a external shut-off to a prepared internal installation with a accessible internal shut-off locatedimmediately after entering the property.they would not reduce down but want the mdpe connected full bore to the internal shut-off.
This is strict Regs but they can vary a bit.
You could install a second external shut-off just before where you propose to Tee-off, this second shut-off would act as your internal shut-off. not great but better than nothing in a panic.

a 22mm internal mains is best but, especialy in low demand flats, some unvented cylinders are supplied by 15mm that increases to 22mm before connecting with the unvented cylinder and they work fine but the cylinder size and your reg installer or mfr's advice will solve that issue.