Emissions to water, heavy metals

Between 2000 and 2014, emissions of heavy metals to water fell by nearly 58 percent, while the economy grew by 17 percent. This implies that overall the Dutch economy improved its environmental efficiency in terms of emission intensity of heavy metals to water.

This chapter focuses on the emissions to water of highly toxic metals such as arsenic, cadmium, chromium, copper, mercury, lead, nickel and zinc. The indicator is calculated in equivalents, which means that the degree of toxicity of each metal is taken into account. Emissions related to run-off and seepage are excluded because these two sources are very dependent on weather conditions.

The issue

The availability of clean water is essential for humans and nature. However, surface waters are exposed to discharges of harmful substances by industries and households, which could cause severe damage to ecosystems in rivers, lakes and coastal waters. Heavy metals occur naturally in the environment, but are toxic in high concentrations. In the light of green growth, the development of emissions of heavy metals by industries and households is relevant because of their impact on water quality.


Emissions by manufacturing have halved since 2000 as a result of various technical measures. Emission intensity has greatly improved in several industries, including the basic metal, food and chemical industries. In addition, waste water treatment plants have improved their purification efficiency in recent years. In 2014, emissions decreased slightly compared to the previous year.
Households are responsible for 69 percent of total emissions of heavy metals. A large part is removed from the water by waste water treatment. In 2014, emissions of heavy metals by households increased again. This is caused by more consumption of products in which heavy metals have been incorporated.