Being food grade plastic, freshwater remains fresh and you won’t experience that plastic taint found with flexible bag and glass fibre tanks.
Black waste is extremely corrosive. The acids in black waste corrode the welds on mild steel, stainless steel and alloy tanks. The surface of a metal tank can look absolutely fine but the welds and fittings will be attacked and this is where failure normally occurs. MDPE is totally unaffected by the acids in black waste.
At Tek Tanks we manufacture from 10 and 12mm thick plastic which gives all our tanks incredible strength but also combats any odour problems often associated with cheaper thinner walled tanks.
MDPE is also an extremely suitable material for diesel tanks being totally resistant to diesel and its thermal properties help prevent condensation forming inside the tank. Although not eliminating it completely, MDPE will greatly reduce the amount of water condensing out in the airspace left. It is always advisable where possible to leave MDPE (and any other) diesel tanks nearly full when left for any length of time.
Natural MDPE is also semi transparent allowing you to see the level of the contents without having to fit a sender and gauge.