The purity of water is something that most people in the developed world take for granted. Water companies operate highly sophisticated processes to give us the water we expect. However pharmaceutical residues may be one area in which their processes are not so effective. There has been an increase in the level of oestrogens in water supplies since the wide use of the contraceptive pill began in the 1960s. Hormones by their very nature are supposed to have their biological effects at low concentration (effects can be seen at parts per trillion levels) and these effects have been noticed. Several scientific studies have shown changes in the sex of animals in the wild due to the excretion of waste endocrine active substances (EASs). EASs are man-made substances such as synthetic hormones used in oral contraceptives and hormone-replacement therapies (HRT) as well as certain chemicals that are used in industry and agriculture. Studies by the UK's Environment Agency have found that sewage effluents can cause egg development in male freshwater fish (this is due to the oestrogens acting as ESAs). Also, other studies have shown feminisation of frogs and masculinisation of certain species of marine molluscs. More importantly for humans the presence of environmental oestrogen can hinder sperm activity in fertilisation and thus be a threat to human fertility. It is well known that the use of conventional sewage and water treatments don't remove oestrogen from drinking water. Clearly there is a problem which could have catastrophic effects on the ecosystem. What is being done? For all the groups studying the phenomenon there are at least as many working on methodology to treat water containing oestrogens and oestrogen-like compounds, making it safe to ingest for both animals and humans alike. One of the latest methodologies for removal of oestrogen from water has been developed by a group in the Animal Metabolism Unit, at the US Department of Agriculture (USDA) in North Dakota, headed by Dr Nancy W. Shappell. The method involves the use of an iron-tetraamidomacrocyclic ligand (Fe-TAML or Fe-B) activator which works in low concentrations to activate hydrogen peroxide, which then in turn acts on oestrogens such as 17a- and 17ß-estradiol, ethinylestradiol, estriol, estrone, and EE2 to degrade them. The Fe-TAML ligand works within 15 minutes to remove over 90% of the oestrogens in waste waters (after 1 hour over 95% of oestrogens are destroyed). The activity doesn't end there - the Fe-TAML hydrogen peroxide complex has also been found to be a potent bacteriocide capable of killing even bacterial spores. There seems to be potential for the new system to treat waste waters and make them safe for human and animal use.