Water Pressure Reducing Valve

That water pressure in water main will not reduce to ‘zero’ but a sufficient amount of residual pressure will always remain present in the main line; which would results in availability of water in all distributary lines, in equal proportions, during entire supply period;
As sufficient residual pressure would always remain available in the water main; no contaminants from outside (of water main) would get entry into the water main and thus contamination of potable water is avoided;
We can easily use water pumps to boost water pressure in various distributary lines, independently, because such an act would not affect to water pressure in water main, as it was previously affecting it very miserably.