In order to maintain acceptable quality the following parameters should be maintained:
- pH 7.2 - 7.6
- Free Chlorine 1.0 - 2.0 mg/l
- Combined Chlorine residual should be kept as low as 0.5 mg/l and should be no more than one-third of total chlorine.
- Total Alkalinity 80 - 150 mg/l
- Calcium Hardness 200 mg/l minimum
- Total Dissolved Solids (TDS) maximum 1000 mg/l above supply water TDS to an absolute maximum of 3000 mg/l (2000 mg/l preferable)
- Sulphate 360 mg/l maximum
Water balance is affected by:
- Temperature
- pH
- Total Alkalinity
- Calcium Hardness
- Total Dissolved Solids
The Langelier formula, sometimes called the Saturation Index, is used to determine pool water balance. The Saturation Index (SI) = pH + Temperature Factor (TF) + Calcium Hardness Factor (CF) + Total Alkalinity Factor (AF) minus Total Dissolved Solids Factor (TDSF).
The value obtained should fall between 0 and 0.5 and indicates the water is in balance.
For more information contact Environmental Health.
Private Water Supplies
Under the remit of the Private Water Supplies Regulation 1991 (to see a copy of the regulation go to www.hmso.gov.uk (this page opens in a new window)), local authorities have a duty to ensure that private water supplies are of good quality and safe for consumption. In general terms a private water supply is ‘any water supply which is not provided by a water company. The source of the water may be a well, borehole, spring, stream, river, lake or pond.’
The regulations specify the requirement and frequency of testing. Supplies are categorised according to their use and classed with regard to the number of people on the supply and the amount of water used.
A public Register of private water supplies in Guildford Borough containing information on test results is held in the Environmental Health Department at the Council offices.
Environmental Health
Millmead House
Millmead
Guildford
Surrey
GU2 4BB
Tel: 01483 444371
Email: environmentalhealth@guildford.gov.uk