Surface water contamination (rivers, lakes, reservoirs or coastal areas) may be caused by:

• The discharge of contaminated aquifers into surface waters.
• The entry in surface waters of streams from contaminated locations.

Ground waters may be contaminated by:

• The migration of pollutants from the unsaturated area to the area saturated with water (aquifer). Once the contamination has reached the ground waters, it may move and affect areas a great distance from the place where the problem was caused.

River sediments may be contaminated by:

• The precipitation of contaminants into the sediments. These sediments can, in turn, cause contamination of the ground waters in contact with them. Likewise, poor management of the drainage of such sediments may cause further soil contamination where they are deposited.

The evaporation of volatile compounds in the soil and/or ground waters can cause a risk of pollutant inhalation, which might have a variety of effects, depending on their toxicity. Those accumulated in buildings might be considerable.

The evaporation of volatile compounds from the soil and/or ground waters may suppose their movement and location in buildings through walls or conducts, causing a risk of pollutant inhalation. In these cases, the accumulation of volatile compounds is usually in the basements of buildings and may be detected in such a simple manner as opening a tap for the gases accumulated in the pipes to appear.

The contamination of ground waters might suppose the contamination of underground wells for agricultural, industrial or municipal use, causing a risk to people through the ingestion of water or the ingestion of vegetables watered with the contaminated water. The supply point where the effects of the contamination are detected may be far away from the place the contamination is caused.

The presence of contaminated soils in public recreational areas or private gardens may cause a risk of contact with the contaminated soil and the possibility of accidental ingestion by children playing there.

Contaminated surface waters in places of recreational use may suppose a risk to people associated with dermal contact with the water, the accidental ingestion of the water or the inhalation of vapours.

Digging work on contaminated soils and lands where there may be pockets of waste may cause a risk to the neighbours and operators associated with toxic emissions, the inhalation of volatile compounds and/or gas explosion.

The use of ground waters contaminated by irrigation or by consumption in farms may have the following effects:

• Livestock consumption of vegetables watered with contaminated water.
• Livestock ingestion of contaminated water.
• Human consumption of contaminated livestock products.
• Human consumption of contaminated vegetable products.