Advice needed on how to diagnose coolant leak - 2010 1.6 TDI

[L162LZ]

Hi All, looking for advice. The water level on my daughter's Polo is slowly dropping and regularly needs topping up.
I've searched and it seems that the common causes could be water pump, egr valve or head gasket?
I've checked the following so far that I read of as possible causes:
1) Can't see any dirt/oil in the water tank.
2) No sludge on oil cap or dipstick (did oil change service a week ago and old oil was fine
3) No apparent steam coming from the exhaust.
4) No sweet smell of coolant in the cabin.

I haven't checked around the water pump or oil filter housing yet for leaks (my daughter's only home at weekends)
Can someone suggest a good way to properly diagnose the most likely culprit that I should tackle first
Thanks

[ciclo]

The repair manual indicates a tool that is an air pressure pump with a pressure gauge that is placed in the filling hole of the expansion/water tank, pumped by hand to raise the pressure to a few bars and checked on the pressure gauge if the pressure droops. (within a range)

In case it happens, the manual only says to locate the leak... and fix it.

I have read that these engines also have leaks through the oil cooler, but it seems that there are several places where the leak could be in this engines.
I guess by removing the lower engine noise insulate and using a flashlight you might be able to find something...

Hopefully someone else can answer your question and share something more clarifying.

[iichel]

perhaps a leaking EGR cooler, a common issue on EA189 TDI engines

[amer6R]

check the hoses going into the cabin ( behind the turbo)

[ciclo]

4-cylinder common rail engine (1.6 l, EA189) CAYA CAYB CAYC