My tree needs killing
 

Hello

I just moved into a new house with a leylandii i like it but unfortunatly it is attacking my water pipes so it has to die.
I don't want them toppled because the trunks seperate my house from next door's house so i want them dead to stop the roots.
I was reccomended to use deep root but have been told i have to use quite a lot.
Does anyone have any reccomendations.

please help
Robert

I know that applying it to the roots is a good idea but i can't get to them.