How can I find the source of water ingress in a Citroen C4 Grand Picasso?

My daughter's Citroen C4 Grand Picasso 2014 has a wet area under the off side rear (3rd row) seat. It is not coming from the underneath of the vehicle as it has not been driven for a while.

Asked on 6 December 2023 by Mr Gareth Parry

Answered by David Ross
Water ingress can occur from several different areas, so it may take some investigation to get to the bottom of it. Window, boot and door seals can be the culprit, as well as drainage channels, particularly if your daughter's car is fitted with a sunroof. It is also possible that the drain pipe for the air conditioning has become blocked which is causing water to enter the cabin. If you cannot find the source yourself, you may wish to take it to an independent Citroen specialist who may have seen this issue before. You can find one using the Honest John Good Garage Guide here:
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