Ya, if you see in the picture, the arm is already bent twice.. I bent it before installing.. However, even I bend it further down, it still will overflow, double triple check the pelampung, no water leak from the main pipe to the tangki, ceiling is not wet, no water dripping from the pelampung.. anyway, i tried your suggestion, same thing haha..

Lol, i no idea what you talking about hahaha..still learning... Check valve = Non-Return Valve = Red Circled in the picture??? Same thing? How do I switch off the bypass?

Sorry Lucifah for asking these, trying to learn few things before I call plumber...hahaha..
Nope, used back the bola.. Bola still useable..sudah rendam dalam air, bounced back like gila high..so still can use..check for holes or leaks, none found! =D
This is what I suspect too...so I think better to change the whole set of valve right?

OK Lucifah, I have prepared the piping flow for you..haha

By the way, in your previous posts, you said  , why you said clever? Can explain abit? hehe sorry bro..i'm intrigued to know...

pakai level sensor lah...abis crita...

saja je lah..u think level sensor cheap meh..  

hi tauke. i think my house water tanks need servicing. u do house calls right?

But if there is no water from SYABAS, the water would flow back to SYABAS main line?
of course i think SYABAS water meter is single way as well.

BTW the sketch of water flow i wrong i guess.
one way valve for master bedroom is wrongly indicated.

rumah TS ni air tank dia kat atas siling. kalau bocor .....habislah....no need 1 year .. air tangki can jatuh already

This valve might help for my dad's place.
Currently the pump is pushing water to the 2nd floor to the tank, then from tank flow back down.. but the pressure is super weak.
If i make a t before the tank with the outlet of the tank do you think this would help?