Private water supplies - guidance on chlorine residual testing

Guidance on the methodology for residual chlorine measurement (and associated calibration and quality control) was issued by the Inspectorate in Information Letter 3/2005 (Annex A) available on this website.

This document sets out the arrangements to be followed by water companies to enable the measurement of residual chlorine on site by their water quality technicians and for the submission of the results to the Inspectorate under the regulations. These same principles apply to local authority monitoring of residual chlorine under the private water supply regulations.

The Inspectorate has advised water companies that they should make arrangements to train local authority sampling staff in sampling/residual chorine measurement alongside their own water quality technicians. Such training should be provided at no cost as part of general liaison/support arrangements between water companies/local authorities.

The Inspectorate periodically audits water company samplers and this includes on site measurements for residual chlorine. In due course, the Inspectorate will extend this to local authority sampling staff.

The measurements are simple and easy to carry out, the equipment is relatively inexpensive to purchase and the local water company can provide advice and training in accordance with the Secretary of State’s requirements (as issued by the Inspectorate).







Page last modified: 30 June 2014
Page published:30 June 2014

Drinking Water Inspectorate