In all situations, consideration must be given to the possibility of the deterioration of piled foundations due to aggressive substances in soils, in rocks, in ground-waters, in the sea and in river waters. Piles in a river or marine structures are also exposed to potentially aggressive conditions in the atmosphere, and they may be subjected to abrasion from shifting sand or shingle, or damage from floating ice or driftwood. In considering schemes for protecting piles against deterioration due to these influences, the main requirement is for detailed information at the site investigation stage on the environmental conditions. In particular, adequate information is required on the range of fluctuation of river or sea levels and of the groundwater table. In the latter case, the highest levels are required when considering the likely severity of sulphate attack on concrete piles or the corrosion of steel piles, and the lowest possible levels are of considerable importance in relation to the decay of timber piles