Coolant loss

Iknow of two boxers one being mine that has sprung a coolant leak between the bumper and the engine at the lowest point (just in front of the oil filter) is a plastic T piece that connects three hoses, the smaller of the three has leaked. Mine needed a top up of about 1/2 ltr. But I couldn’t find the leak. Topped it up and the coolant dropped again so another look and it was obvious this time.
Though perhaps others should check.