i am thinking 2 pipe to each bathroom. one to toilet bowl and one to basin + shower. Reason - no need to wait after flushed toilet to take shower.  Correct ar?

@ozak: i yet to show my plumber my sketch (= your drawings with minor modifications ).

In your drawings, there are 3 independent outlets from tank to bathrooms. what if i need to install a pump after tank to bathrooms? Can i straight tap out 1" pipe from tank to pump then, pump outlet 1" branch to 3 nos 3/4" or 1/2" till bathrooms? means, 3 bathrooms having common inlet pipe, is this ok?

possible to use poly pipe for house interior conceal in wall ?

but i heard that termite will attack poly pipe rite....if orange-pvc is used to conceal the poly, does it work ?

*Any tips or ideal to setup high pressure water from tap to hose and nozzle for car wash ? coz once i turn the tap for max flow, the hose always burst out then everything in mass lol

Note: Area of circle = PI R square.
1 inch pipe area = (22/7*1/2)x(22/7*1/2)=2.47sq"
1/2 inch pipe area =0.617sq"
2.47/0.617=4

For internal house water tank, the best is actually poly tank. Comes in many shapes and sizes. Light, cheap, easy to service and maintain. Only setback is that every few years must perform full internal cleaning to get rid of the blue algae.

yes, i was told by my plumber. He discourage i use poly pipe for whole house piping... no one heard of it before though.

Where can I get those Gauge? planning to get one to play around.    Also, how much does it cost anyway?

yes, same. but yours c/w check valve & by pass line
still, what is the "at least" height for tank-1st flr?

@ozak: what kind of check valve you using? Brass swing check valve? Checked with hardware shop, 1" approx. RM20+ per pc. not expensive. "i” brand. can't find other brand. any recommendations?

alamak..no one hv idea on my concern meh.. huhu

Stainless steel would be considerably more expensive rite? For hot water in planning to use copper pipe. But is there a concern pvc pipe joins can't take the pressure from the pump?

how is the cost comparison va pvc pipes? May I know how much did it cost to do up your house?