Hi guys,

I'm having some kind of weird problem that I cannot figure out the source.....

My water tank is overflowing like waterfall dei...not sure if it's related, but it happened right after the maintenance by SYABAS in gombak area (batu caves).

Went to the bumbung to check, panjat here panjat there, found the tangki..opened the tangki, checked the pelampung, ok i think it's time to change the pelampung..damn hard to unscrew it..

So the process of changing the pelampung went well eventually. I thought I have solved it..but after a few hours, started overflowing again.....   

Went back to the bumbung, suddenly tengok-tengok, the tangki full (above normal level).. Turned off main pipe, opened some taps to reduce the water level in the tangki..then checked the pelampung back again.. here are some pictures,
1) Checking the newly bought and installed pelampung set... Tangki is being filled..

[attachmentid=5182311]
2) Tried hand-stopping the pelampung, good, no water dripping...

[attachmentid=5182312]
3) Water automatically stopped, meaning no dripping. confirmed pelampung ok..

[attachmentid=5182313]
4) Now the water level still rising, until the pelampung also tenggelam....started overflowing again...

[attachmentid=5182343]
Now i really pening what could've caused the overflowing problem....I suspect it's the non-return valve.. But, well.. i don't know where it is, don't know what it looks like..and too many pipe connection...lol..

Can someone help me pleaseeee....tension gila!
------------------------- UPDATE ---------------------------------

Went back again to the roof, to take some pictures of the pipe connection just in case some one can help pinpoint the problem.

THIS IS THE FIRST TIME I WENT TO THE ROOF, SO VERY THE MESSY...NEVER KNEW SO MANY SAMPAH SARAP HERE LEFT BY THE OLD CONTRACTORS..ISH ISH ISH       
1) Is the red circled the NON RETURN VALVE? The black pipe is the main pipe from outside into the tank.

[attachmentid=5182339]
2) Is this too?

[attachmentid=5182342]
If the non-return valve may be the cause, how much would it cost? can D.I.Y ke???? easy?? if can, I might do it myself... hujung bulan no gaji yet...     
The flow of the piping:

1) [attachmentid=5182656]

2) [attachmentid=5182659]

3) [attachmentid=5182664]

4) [attachmentid=5182665]

5)[attachmentid=5182668]