Dee Water
British Triathlon quotes the ITU guidelines for water quality in section 3.3 of its Open Water Swimming Safety Guidelines 2008.

The Deva Triathlon, Dee Mile and Deva Divas events are timed to avoid high tides when Dee estuary water can be washed up over the weir at Chester.

Upstream of the weir, the River Dee is well monitored by the Environment Agency and the various water companies that extract water from the river. Much of this goes to supply drinking water to the citizens of Chester and the surrounding towns and villages.

Despite this, the task of obtaining meaningful data for the levels of potential pollutants such as E’coli and Entero-cocci has proven to be extremely difficult. In fact, it has been impossible.

During normal summer flows, and when the river is not in spate, levels are generally low…

Both the Dee Mile and Deva Triathlon have experienced extremely low incidences of upset stomachs following the events: nothing serious and nothing directly and clearly attributable to the river.

It is, however, an open river and swimmers should remember this.


Data source: Environment Agency
Chester Tri members swim in the Dee from Eccleston Ferry each weekend from May to September. This is about 4km upstream of the Dee Mile and Deva Triathlon swim courses. Each year they also complete the 4km swm between Eccleston and Sandy Lane Ferries – with no serious ill-efects.

BOD (Biological Oxygen Demand) is a measure of general organic pollutants. Values below 1 indicate a pristine river. Much of the time the Dee’s water is below this level. The higher values in the charts above are still well below values for a seriously polluted river. The slightly elevated values coincide with high tides and/or heavy rainfall.

When entering the Dee, swimmers are reminded to take care of hidden objects which may be present.

When entering the river from or near a bank, it is advised that swimmers lower themselves into the water. The the landing stage provided for the Deva Triathlon is used buy the tripper baots so should be clear and relative deep. Although this area should be clear of underwater debris, diving and jumping are not encouraged. Please have fun but be a little

We are always looking for people to support our rides and events, either as a navigator or as a coach! Please get in contact with Dave if this is something you would like to be involved with.