I thought PVC has no problem with UV or the sun but not heat. Heated it melt like icecream. Infact PVC is the best plastic against UV.

ABS plastic will melt with sulpheric acid but ABS is very strong and unlike PVC heat is not a problem but of course you dont use it for hot water piping. ABS can take load and use underground and withstand weight and pressure. ABS is the pipe you must not expose to sun/VU it will disintegrate.

If you need a strong pressure cold pipe use ABS for pump in the wall for example. PVC class 7 will reduce volume flow due to its very thick layer. You dont use stainless steel or copper pipe for cold pipe it is very expensive, not only the pipe the joints as well many times over the price of PVC and ABS.

For meter main going underground to house use poly as it is flexible you can bend and turn around it and there is no joint. For underground never have any joints there. It should be one long pipe from meter to the other end surface up. You will never have problem leaking underground. From there you either use PVC or ABS for internal distribution. If you use PVC or ABS for underground you got to connect and when there are joints there are future troble. Same goes for S steel and copper not only it is expensive you cannot have long pipe but need to join. Joining is always no no no for areas you cannot access.

Use stainless steel joints at the end pipe (example) from wall outlets to connect to your taps, toilets, basin, etc. Becasue these "heads"at one time or other you need to replace the taps and to unscrew or rescrew on PVC and ASB you could use too much force and break the thread.

Copper is easy to install and connect and to disconnect and yet cheaper than stainless steel for hot water supply. But never step on it or bend it walking over. It shouild be on roof top or wall.

the best for underground from meter to kitchen is stainless steel but the price is high. Just use poly or PVC....for PVC not recommend direct expose to sunlight..but for PVC class 6 & 7 should be ok. poly and PVC easy to maintain if leak.

tips : you should run the water pipe along at the fence (under ground) so that when leak easy to maintain. do no run the water pipe under ground through your hall,room,etc...if leak..problem.
for info...my renovation 22x42 feet is at the back of my existing main house. existing house already had 2 water tank..i add another 2 water tank for my new reno house..that means my house got 4 water tanks.

another tips to share: for my kitchen i design sink got 2 pipes..one pipe from water tank , the other one direct from main. So when water shortage..i have no problem washing dishes......

poly pipe aka HDPE

The Advantages of HDPE are as follows:
Non-toxic
High impact strength
High resistance against corrosion-internal and external
High chemical resistance
Toughness
Flexibility
Ease of handling and laying
Can be made in long lengths
Excellent resistance against abrasion
No build-up of minerals on inside walls, i.e. crustations
Weather resistance
Expected life of 50 years or more
Smooth surface with low friction losses, i.e. hydraulic smooth C-value (Hazen Williams) = 150-165, K-value (Prandtl – Coalbrook) = 0.007mm
Very low water absorption
No stress cracking
Suitable for high temperature application (PP)

http://www.sansico.com.my/technical-data-m...-data-hdpe.html

i know about your design..i purpose design my pipe like that cause i want my water tank moving water...i dont want water in my water tank statik for long time.

then...it is very good..i just want to know..does your water pressure drop if you open both tap in the kitchen since they are coming from same main.

you are good in plumbing.......actually i design 2 water taps in my kitchen, one from tank and the others from main so that i can use both taps and sink bowl at same time....that why i dont use the valve system.

got use pump ? else the water pressure low leh..

Your way of piping save one piping and the best is it is auto no need to shut off main supply to have tank supply. But dont you have problem with low pressure with one way valves and the valves after some time like 3 to 5 years get jammed and need replacement?

Hahaha, you are one smart fello. Alge will grow only when I shut it off. Our tap water has chlorine and that kill any micro organism. I shut off one of it and no long algea grow. Just dont know how algea can get in??? And yes under the sun. This filter housing can take sun heat and UV.

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Added on February 24, 2012, 10:13 pm
For RM12 I can get 4 pcs 5 microns in Jalan Pasar, Tesco or Giant and pasar malam. You could have bought from a shop in jusco? who specialised in water filter. those people sell in small quantity and also buy in small quantity of course have to mark up high. You can buy from me if you want to half price rm6 a pc. I'll buy from tesco and re-sell you okie?

Didn't I show you the pix how to overcome low pressure? Look and study the pix ok?

You are right "rough face" but that is 10 micron type. Not good. I also tried the string line type, yes it is better last longer, not easily clogged but still it is 10 microns. When clogging and pressure is a problem use more in parallel. In my areas there are ppl using only one at the meter because we have no pressure and flow problem.

Hai ya what same like me la? I use the charcoal for my drinking water filter. RM10 only a piece. It also absorbs chlorine and chemicals. You will know it is time to change when the water smell chlorine but I change it early. Cheap ma. In fact it can last a year according to its recommended volume. This are activated carbon block make from coconut shells. The best activated carbon as recommended and widely use in US for water purification use together with RO. In fact WHO recommended it to be save to drink once water passed the activated carbon filter.

i dont hire plumber..i m the plumber..just hire indo..i m the supervisor..i design from A to Z...i thought that ABS is good since it is new.....until i experience it..that why i advised forumer donot use ABS....
i design my house from main using 1 1/4 inches pipe then branch out to 2 to 1 inches pipes..i got 4 tank2...2 at main house, 2 at new house..the reason i m using 3/4 inches in toilet is i hv sufficient water volume...

with all these design..my shower head need not any pump....no problem with water volume and pressure...

Ya, termites attack poly pipe, asked a few friends and no one heard of it. Anyhow, this will not be the draw back to choose poly material.

I prefer poly pipe simply because it is flexible (than rigid abs), bend-able (to certain extend) and most importantly it does not rely on gum to seal but thread. I think above reasons make me feel more comfortable to conceal it in the wall, since wall/ground does "move a little bit" from time to time.  Is my "theory" correct? Should i "hold tight" on these points and insist using poly pipe for my house?

On the other hands, i hope to copy ozak's way in doing backup supply for kitchen, i.e. bypassing from tank to tank's inlet. But can someone tell me how is the piping size like should be for the whole house?

@Ozak: You did mentioned "the check valve and the rest of the pipe are 1 1/2". This means ALL FOR THE BYPASS SYSTEM, is it? And the check valve near meter should be 3/4" (follow main)?

So far after reading from page 1, what i could understand is: The main (meter-tank) should be 3/4", then tank to kitchen and baths should be 1/2". If higher flow is desired for bath, then tank to kitchen use 1/2" but use 3/4" or 1" for bath. Someone please advise if I got the info correct.

guys, on tank which one is better, fiberglass or those stainless steel?

Ozak, just out of curiousity...if SS is installed between the roof trust and roof tiles...can the trust take the weight? since SS is heavier?

thank you for the drawings.

1. According to my plumber, my house reno but never involve front portion of the house, i.e. living hall. Therefore, i have to lay main straight to tank. Correct?

2. He will use poly 1" pipe. for above.

3. From main (on the roof, before tank), branch out to kitchen and bathrooms (ya, all 3 bathrooms). He will install a check valve here so that when no water from main, water from tank flow to kitchen and bath. Correct? Should add a check valve at main after meter/outdoor filter to protect it from back flow?

4. He proposed to use blue ABS 1" though my initial plan was using poly 1/2". I like to have that 1" pipe for all kitchen and bathroom cause i hope to get higher water flow. But material wise...

@ozak: from your reply, can see you prefer pvc over abs. any particular reason? To me they are just the same. Both rely on glue for sealing, rigid etc. For household use, i seriously do not think there will be a need to prevent acid or chemical attacks. So till now, my question is unanswered. 

5. Now i re-think, during water cut only we will use tank water. This means water that we use that time is "not fresh". So we treat it as "back up/emergency use for kitchen only"?

too much questions but still hope you guys would advise

3. From main (on the roof, before tank), branch out to kitchen and bathrooms (ya, all 3 bathrooms). He will install a check valve here so that when no water from main, water from tank flow to kitchen and bath. Correct? Should add a check valve at main after meter/outdoor filter to protect it from back flow?

what did u use to draw?

@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?