Image of Exterior cold water storage tank with two ladders. Illustrates Cistern and Tank Maintenance

A Cistern or Tank used for potable water storage within England and Wales requires compliance with the requirements of Schedule 2, Section 16 of the Water Supply (Water Fittings) Regulations 1999.  Similar Regulations also apply in Scotland and Northern Ireland.

A Water Tank installed in commercial, industrial and institutional buildings for potable water provision requires the owner, within his duty of care obligations to users of these establishments, to conduct an annual inspection of the tank to provide assurance the water stored is at the required wholesome quality.  Water samples require to be taken and the condition of the tank structure noted.

Should any significant level of debris be observed internally and / or water quality is less than the wholesome level required it is recommended the vessel be drained, internal surfaces washed down, the tank re-sterilised and the water quality rechecked before returning it to service.

During inspection the following are some of the critical observations required.

  1. Are there any damp or wet patches around the tank base?
  2. Are any tank connections leaking?
  3. Is the tank support base adequate?  I.e. Flat, level and unyielding to <1/500 of its length, breadth or span.
  4. What is the condition of the tank’s inner and outer surfaces?
  5. Are the sidewalls showing signs of bulging or undue distortion?
  6. Is the tank internal clean and the base free from debris or silt?
  7. For Sectional Tanks, a check should be made on panel bolt tightness.
  8. Is the tank insulated appropriate for the duty?
  9. Has the tank a fixed, close fitting Lid or Cover?
  10. Has the required and appropriate anti-siphon Air Gap between the Inlet Supply and the tank’s Critical Water Level been provided?
  11. Is the Inlet Control (Float Valve) capable of closing off drop-tight?
  12. Are the Screened Warning and Overflow Pipe Fittings of the appropriate size and located appropriately to provide the required protection and are their respective screens fitted, clean and unobstructed?

Modern-day cisterns and tanks are unlikely to suffer from the structural defects listed 1) to 5) but tanks of some vintage could well require considered attention.  Irrespective, a check should always be made regarding the main Regulatory requirements listed 6) to 12) to provide the necessary assurance on tank design and water quality.

Note: The above information is advisory only.
Author:    Ian McCrone     BSc.     CEng.     M I Mech E
Past Chairman of ATCM
Copyright ATCM
Download Article PDF