3.1 Water Standards

The standards being proposed specifically aim to achieve the protection of human health, living resources and ecosystems, amenities and other legitimated uses of the environment, from negative impacts resulting from
pollution. The beneficial uses which need protection include, among others, drinking water sources and supplies, irrigation, fisheries and recreation.

Each of the beneficial uses of water require certain quality characteristics which are usually specified in applicable criteria. To achieve this, it is necessary to select the most reasonable level of each criterion so as to come up with a number of criteria viewed as specifications describing the overall water quality recommendations, including the safety margins, inherent in each criterion. This has involved review of studies carried out in various parts of
the world with regard to heavy metal toxicity and safety margins, effluent standards, receiving water standards and drinking water standards, applicable
to different countries and finally an evaluation of the Tanzania temporary effluent standards

Considering limits allowable for waste waters, different scenarios were considered and discussed, for example, an dilution at the centre of big water bodies like lakes Tanganyika or Victoria, and other small water bodies. By
assuming extreme environmental conditions ( that is minimum flows and maximum temperatures likely to be encountered) and minimum waste-water dilution factors (in some cases as low as 10) for the limited water bodies, a number of specifications were derived.

3.1.1 National Standards on Municipal and Industrial Effluents

The on-going process of proposed discharge limits, is attempting to ensure that each industry has to comply with precisely the same minimum environmental requirements governing discharges.
To begin with, all industries in the country have been put on equal competitive basis as far as environmental precautions are concerned.

In future, industry specific limits will be considered in separate standards, to take care of volume of discharge, concentrations of industries in one area, and discharges peculiar to specific industries.

So far, attention is mainly being focused on waste-water limits because of its potential to pollute water bodies. The waste-water standards are single level/stage, fixed centrally and apply to all discharges throughout the country. They are meant for production techniques and more effective techniques of waste management and disposal. They are set to provide more safety margins without unreasonable specifications of levels of discharge; and they seek to achieve and maintain quality of water in all water bodies in
Tanzania, at levels suitable for various uses.

In most parts of the country there are no treatment facilities for waste-water; and for some of the municipalities and industries attempting to carry out water treat, the processes are not effective enough due a varied number of reasons. For this reason, more attention has been given to discharges which flow directly into water bodies, presumably without (adequate) treatment. As such, most limits assume this scenario.