you suggesting he places a very high header tank ??. how does he get the water up there ?? pump ?? unless of course you heat the water up inside the closed main to increase the pressure. Kinda kills the grass using boiling water to sprinkle the lawns.
All advice is given with-out seeing the job, and hence all advice MUST be taken as advice with limited knowledge on the exact situation. NO responsibility can or
will be taken. And yes, I am a licensed plumber with my own business in Brisbane Australia