The leak is from the kitchen sink waste pipe. They came across this after moving back in after winter and cleaning and noticed a substantial amount of water under the sink.

The water has seaped behind the sink, down to the skirting and onto the lounge units, a lot of which are now blown, which indicates this leak was happening prior to when we closed for winter.

Upon investigation by our team, it appears the down pipe which is connected to the u-bend is a push in one. This has now been replaced by a screw in ubend connector.

Having spoken to our team, they do not touch internal fittings when siting, all their work is under the caravan connectivity. The owners did check initially for any leaks, as we do instruct them to do so, but because of the connection being a push in one, it has obviously over time slowly fallen down to the point there has been no pipe. - we would therefore like to put this issue back to ABI for poor connectivity.