House no need class 7 lar, pvc class e = pn15; can stand 15 bar. household with pressure booster pump normally 40psi=3bar only

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.

Seem like the best for the money is poly (PB). Cheaper than stainless steel, flexible and screw type joint which is secure. But chemical and corrosion any problem for underground?

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

You don't need 2 pipes for your kitchen inorder to backup incase no water. For my home, I install a bypass pipe from the water tank to the water supply pipe for the tank. In the middle of the pipe, instal a check vavle. Than install another check vavle at your meter outside.

When no water come, the water tank pressure is greater than supply. Plus the gravity, the water will flow back to the main pipe. And your whole house have water from your tank include your kitchen. Even you can wash your car. 

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Added on February 24, 2012, 9:39 am
Sound like a best choice to use this material for the main pipe. Second to stainless steal.

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.

I have 2 water tank and all my bathroom is connect to the tank. So the water is always moving and no statik. While the kitchen and the garden is main.

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.

The kicthen only have 1 tap. Either the water from the main or tank if no water. If the water pressure is low, than I know there is no water from the main. Cause pressure from the tank sure is lower than the main.

When the main have water, it will shut off the vavle from the water tank. Cause the main pressure is greater than the tank. The whole auto system is using the pressure to run.

I have 2 water tank and all my bathroom is connect to the tank. So the water is always moving and no statik. While the kitchen and the garden is 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..

I have few yrs experience in plumbing.   Your system is not wrong. Just the cost is expensive to do.

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Added on February 24, 2012, 10:59 am
No pump. It is juat a backup when no water. Not everyday use. As long don't effect my daily routine.

want opinion from you all, should i change outside pipe before meter with stainless steel as Syabas did not replace unless the pipe rusted (my old pipe is using GI about 10 already) cause i plan to install rocket filter.

TQ

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?

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?

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Added on February 24, 2012, 1:07 pm
No problem changing "syabas" pipe outside before meter. Syabas shoiuld have replace all the GI pipes that cause dirty rusty water. When there is no water supply and when supply resume all the rust will be flush out into our house that is why we need whole house filter.

You should choose other than the sand rocket filter. Somehow the tiny sand will get into your house piping, into water tank, heater tank, blocking taps, etc. I replaced my sand filter with simply cheap acrylic filters for the whole house.

House no need class 7 lar, pvc class e = pn15; can stand 15 bar. household with pressure booster pump normally 40psi=3bar only

R u sure pn15=15 bar? dunno anything dun talk rubbish, k?

TQ..where to find the acrylic filter?...got pic?