Normally and logically this is pipe sizing for home in malaysia.

1. The incoming pipe from water work before meter is 3/4 inch.
2. Going into the meter is half inch size with a lenght of approximately 1 foot in length.
3. Due to high pressure 3/4 inch pipe before meter it is logically to have 3/4 inch pipe from meter into the house than to use half inch pipe so that the pressure is not affected. It serve no purpose to have bigger size pipe than 3/4 as it is not going to help increasing the in coming pressure neither will 3/4 inch pipe reduces the water pressure even when it branches to kitchen and up to tank. But having bigger than 3/4 size pipe does no harm.
4. From the tank to the bathroom is a different story. Depending on how many per outlet from the tank serves the pipe from tank has to be at least 3/4 size pipe per bathroom as it is place flat.
5. Then as it come down to the bathroom with the help of gravity the rush of water the pressure increases so reduced to size of pipe to half inch is ideal. It is not necessary using biger size like 3/4 inch pipe. By doing so you got the extra unncessary work to have pipe reducer from 3/4 inch to half inch as the tap and outlets accepts only half inch pipe. More so when it is concealed you dont want to hack bigger than necessary channel for the pipe.

From pump 1 inch you should continue to branch to 3 nos 1 inch or at least 3/4 inch, not 1/2 inch until the bend going down the bathrooms you use a reducer from 1 inch or 3/4 inch into 1/2 inch. 1/2 inch with 3 outlets (not inlets) in the bathroom is ok. When you brush your teeth you are not bathing at the same time right. Also toilet will very soon full with pump in few secounds. No problem for bathing. If you use 3/4 or bigger pipe down the walls you still have to reduce the pipe to 1/2 inch at the outlets which is not advisable. Difficult to have big pipe in wall and unneccssary reducers.

No problem when you have pump or without pump as the pipe serving all the bathrooms is bigger pipe than the 1/2 inch pipes in the bathroom.

1 inch pipe is 4 times the area/volume of 1/2 inch pipe. 3/4 pipes is 2 x the size of 1/2 inch in flow volume.

Never heard of termite attack poly pipe. I have my poly pipe underneath soil for 10 yrs and there are garden termite the one with big head and house termite the one attack houses at my garden.

I dont think any animal can eat plastic or poly non-bio degradable things.

When you have pump it does not matter much if you split from 1 inch into 1/2 inch since the pump has enough force to push up the water pressure.

When you have no pump logic tells you that the pressure it has is the height of the tank location to its outlets. It is all about gravity and the pressure is usually low due to the limited height. In such case you got to consider the right size of pipe with below consideration:

1. Water that run flat will be slow as such you need bigger pipe. This is from Tank to each individual bathroom before going down.

2. water that runs down has gravity assist therefore need not have to use big pipe, it doesn't help much or at all.

3. The outlets are 1/2 inch, having bigger than half inch does not help the volume flow for pipe coming down with gravity.

In conclusion the proper sizing is:

1. From tank running flat = 1 inch. 1 inch pipe can support 4 nos of 1/2 inch pipes without suffering lost of pressure.
2. From roof to bathroom = 1/2 inch

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

This post has been edited by stevie8: Apr 23 2012, 11:11 AM

There is no need to go into calculation. The formula times this divides by this etc and getting the calculated result and to understand if it is sufficient is a headache itself. It makes little sense with figures like how many psi when you are not sure how many psi you require by your heater or your preference.

Simply work on the height and pipe size will do:

1. The higer the location of tank the greater the water pressure at the bottom of the openings (taps) regardless how much the tank water holds. It can be a big tank or a smaller tank when they are at same height the static pressue are the same. The height of the tank no doubt has higher pressure but by a few feet (maybe just 2 feet). You put the smaller tank higher by 2 feet the pressure is same as the taller tank.

2. The smaller the opening the higher the velocity of water given that same static pressure. It is therefore better to have a one size larger pipe before the end tap by reducing the pipe to accept the tap. eg. 3/4 inch pipe all the way till the tap with 1 inch connection.

This means, try to put the tank as high as posible at roof top and size the pipe make sure the total output of the opening tap is smaller than the supply pipe size.

Given a double storey house, water from tank cannot give good static and velocity presure to the 1st floor bathroom as it is not high enough. Therefore, a pump is needed or if you use instant water heater it is advisable to have a built-in pump.

As for the ground floor bathroom you can choose to have a shower head with tiny little holes to increase the velocity pressure if the instant water heater has no built-in pump.

For instant water heater without built-in pump one other way is to feed the water heater from direct main. Direct main presure is much greater than the pressure from the tank othewise it cannot fill your tank.

In short:
1. To feed your heater from tank buy heater with built-in pump or
2. feed directly from main. And
3. have a pump at tank feeding all the bathroom. With a centralised pump you do not need to bother the sizes of the pipe as this high power pump can give you more than enough pressure (static or velocity) even with half inch pipe all the way.

This post has been edited by stevie8: Apr 28 2012, 02:09 AM

There is no much different between the three. They will last you yrs after yrs.

For filtering dirt and rust get 2 or 3 cheap filter housings connect them in parallel.

Using ceramic you got to clean it. Whereas using the nylon cloth like filter you just change and throw.