Polyethylene will not corrode when used for waste, Aluminium will. Aluminium tanks could show signs of corrosion within a few years.

Aluminium tanks should not be used for water because there is a possible link to Alzheimer’s disease when used for drinking water tanks.

Aluminium tanks have been known to crack at the welds when used in high performance applications.

Aluminium tanks need to be painted in a marine environment to combat corrosion, painting adds to the cost and has to be checked and repainted when necessary. Polyethylene tanks need no further treatment.

Corroded aluminum tank

Aluminium tanks need to be earthed to the boat’s electrical system. Polyethylene tanks do not need earthing.

Contents are generally visible with a polyethylene tank, Aluminium tanks need a sender.

Polyethylene fuel tanks will almost eliminate condensation within the tank. Metal tanks have to be kept filled when not in use to reduce condensation. Water in the fuel can cause engine problems.